Deterministic quantum teleportation through fiber channels - <AUTHOR> http://advances.sciencemag.org/content/4/10/eaas9401 <comment><USER2> In this work, continuous-variable quantum states are being teleported. The reason they almost-incorrectly call it deterministic is that continuous- variable [1](think analog) quantum states even when degraded by signal transmission errors will always transmit some information to the destination. Qubit (or discrete state) teleportation on the other hand will usually have some probabilistic errors that completely destroy the signal.

Therefore, the correct metric to report for analog signals is the fidelity. They do report this as 69% - which is above a certain important threshold - but also fairly low for any practical application in the near future.

[1] as opposed to discrete-variable states eg. qubits

<comment><USER3> I work in this field and I can not really make sense of your statement. "Fidelity" the way they define it has nothing to do with whether they have a qubit or any other system (infinite dimensional or not).

</comment></comment><comment><USER4> The number one problem with quantum teleportation is the name. It should have been named quantum telegraphy. There would be fewer cranks.

<comment><USER2> The original paper [1], written by some of the best scientists of the era, correctly called it "Teleporting an Unknown Quantum State", and nowhere did it use the term "quantum teleportation". Later, in interest of conciseness, the ambiguous term "quantum teleportation" got introduced. It would have been better if "quantum state teleportation" had been used.

[1] [https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.70...](https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.70.1895)

<comment><USER5> but quantum state is all that can ever be measured about the system so seems a redundant word

<comment><USER6> No mass is teleported, that's the key. A state of one mass is copied to another mass, but no mass is moved in the sense that would invoke General Relativity, _as far as I understand._

I suppose teleporting a state in such a way that the target mass would change its motion in a significant way ("accelerated") without affecting the source mass is impossible, because it would break the conservation of impulse.

<comment><USER7> Quantum copypaste.

</comment></comment></comment></comment></comment><comment><USER8> For anyone wanting a layman's description of QT:

[https://blog.rongarret.info/2014/12/quantum-teleportation- de...](https://blog.rongarret.info/2014/12/quantum-teleportation- demystified.html)

<comment><USER9> I agree that the cartoon that you criticize is confusing. Starting with the first panel, because it doesn't make clear that Alice doesn't know the color/state of her photon. If she knows it's yellow she only has to tell Bob to prepare a yellow photon and there is no need for an entangled pair to make it possible. The whole point of the setup is to be able to "teleport" an arbitrary unknown quantum state.

But the following doesn't seem correct:

> when Bob receives Alice's bits, he uses that information to apply one of > four transformations to his photon. It is Bob's action that changes his > photon's state into the state of Alice's original photon. And that is the > _only_ time that Bob's photon changes state.

To recover the state being "teleported" by Alice, Bob has to apply one of the four pre-specified "rotations" (unitary transformations) according to the two- bit message he receives. In fact one of the operations is to do nothing, sometimes the state of his photon is already the state of Alice's original photon.

Of course this is true only after the measurement performed by Alice. Previously there was no relationship between the state of Bob's photon and the state of Alice's "source" photon: the probability of the state being the same (or related by one of the three other pre-specified rotations) is essentially zero.

<comment><USER8> > sometimes the state of his photon is already the state of Alice's original > photon [but] this is true only after the measurement performed by Alice

No, that's wrong. Alice's measurement does not change the state of Bob's particle. There is no measurement Bob can perform on his particle which will tell him whether or not Alice has performed her measurement or not. Quantum teleportation is no different from regular old EPR in this regard.

> the probability of the state being the same (or related by one of the other > three pre-specified rotations) is essentially zero.

Actually, it is precisely zero. The entire claim that the state of Alice's particle is teleported intact to Bob is actually a lie.

What _is_ true is that no measurement can distinguish the state of Bob's particle (B) after teleportation from Alice's original (C). But this does _not_ mean that the particles are in the same state. Before teleportation C is in a pure state, and B is in a mixed state (as is A). The Bell measurement that Alice performs on A and C entangles them, and the result is a three- particle mutually entangled system, plus two classical bits that tell you how to tweak B so that its measurement outcomes are the same as C's. But B is in the exact same (mixed) state after Alice's measurement as it was before.

BTW, there _is_ a measurement Bob can perform, not on a single B, but on a collection of B's that will reveal that all the B's are in fact in a mixed state. If you want to go down that rabbit hole, read this:

[http://www.flownet.com/ron/QM.pdf](http://www.flownet.com/ron/QM.pdf)

<comment><USER9> > Alice's measurement does not change the state of Bob's particle.

> There is no measurement Bob can perform on his particle which will tell him > whether or not Alice has performed her measurement or not.

These statements are not equivalent.

> Actually, it is precisely zero.

I meant that it's zero as in "the probability of a random real number in [0 1] to be 0.5 is zero", but not as in "the probability of a random real number in [0 1] to be 42 is zero".

> What is true is that no measurement can distinguish the state of Bob's > particle (B) after teleportation from Alice's original (C). But this does > not mean that the particles are in the same state.

C was a pure state and now B is described by the same density matrix so it is necessarily the same pure state.

> But B is in the exact same (mixed) state after Alice's measurement as it was > before.

B is in a different mixed state afterwards and the two-bit message enables Bob to distinguish between the four potential pure states and recover Alice's original pure state C.

<comment><USER8> > These statements are not equivalent.

Why not?

> C was a pure state and now B is described by the same density matrix

No, it isn't. All of B's measurement outcomes are the same, but the density matrix is necessarily different because B is in an entangled state. If this were not the case then it would lead to FTL communication.

> B is in a different mixed state afterwards

That depends on what you mean. The only difference is that afterwards, B is entangled with C as well as A, so now the joint A-B system is in a mixed state whereas before the A-B system was pure. In that respect, yes, B is in a different state. But viewed in isolation, B's state is exactly the same after the A-C entanglement as before.

<comment><USER9> >> C was a pure state and now B is described by the same density matrix [after teleportation, i.e. after the whole procedure including the two-bit message reception and corresponding transformation]

> No, it isn't. All of B's measurement outcomes are the same, but the density > matrix is necessarily different because B is in an entangled state. If this > were not the case then it would lead to FTL communication.

The density matrix describing C at the beginning and B at the end is the same (otherwise how could all measurement outcomes be the same?) and B is not in an entangled state. I don't see how this leads to FTL communication, the procedure requires Alice to send a (non-FTL) message to Bob.

>> B is in a different mixed state afterwards [after Alice's measurement]

> That depends on what you mean. The only difference is that afterwards, B is > entangled with C as well as A, so now the joint A-B system is in a mixed > state whereas before the A-B system was pure.

B is no longer entangled with the A/C system after Alice's measurement.

> In that respect, yes, B is in a different state. But viewed in isolation, > B's state is exactly the same after the A-C entanglement as before.

For the sake of the argument, let's say that Alice knows that the original state C is |up> and that after performing her measurement she sends to Bob the message "you don't have to do any transformation, the state of B is now equal to C, i.e. |up>" (this case will happen eventually if we repeat the experience several times). If, according to you, the state of B is exactly the same after Alice's measurement as it was at the beginning of the procedure, how do you explain that the state of B is |up> at the end? Or what would you say is happening to B, if anything at all?

<comment><USER8> > The density matrix describing C at the beginning and B at the end is the > same

No, it isn't. C starts in a pure state. B is created and always remains in a mixed state.

> (otherwise how could all measurement outcomes be the same?)

Because you cannot distinguish a mixed state from a pure state when measuring only a single particle. You _can_ distinguish them if you make measurements on multiple particles in the same state: pure states produce first-order interference. Mixed states don't. (This is just the old QM trope about "measurement destroys interference", which is not quite true. _Entanglement_ "destroys" interference, except that it doesn't really, it just destroys first-order interference.)

> B is no longer entangled with the A/C system after Alice's measurement.

Yes, it is. The only way to "undo" an entanglement is to bring the originally entangled particles back together at the same location, i.e. it is essentially impossible. If you could cause an entangled particle to become unentangled (i.e. to transition from a mixed state to a pure state) by performing an operation on its partner then you could do FTL signaling by observing the presence or absence of first-order interference.

> how do you explain that the state of B is |up> at the end

It isn't. It's in a mixed state. It is no different than regular EPR with only two particles. If Alice measures A and gets the result "up" then Bob is guaranteed to get "down", but that does NOT mean that B is in the |down> state. It is still in a mixed state. |down> is a pure state.

It is important to remember that mixed states and pure states cannot be distinguished by making measurements on a single particle, so if there is only one particle this is a philosophical distinction, not a scientific one. But if the experiment can be repeated, then the fact that B is mixed can be experimentally demonstrated, with all the usual caveats about quantum weirdness. The point is that QT does not introduce any new weirdness that wasn't already there in EPR.

<comment><USER9> In case anyone else is reading this, I want to make clear that I'm giving the standard description of quantum teleportation.

[https://en.wikipedia.org/wiki/Quantum_teleportation#Formal_p...](https://en.wikipedia.org/wiki/Quantum_teleportation#Formal_presentation) provides a clear description of the initial states of C and A/B, the operations performed by Alice and Bob and the final state of B (which is identical to the initial state of C).

Clearly you don't find this description correct but I would be surprised if you can write down an alternative description that makes sense.

You're free to have your own theory, but I don't understand why do you feel that you need one in the first place. What is the problem with measurement breaking entanglement?

> If you could cause an entangled particle to become unentangled (i.e. to > transition from a mixed state to a pure state) by performing an operation on > its partner then you could do FTL signaling by observing the presence or > absence of first-order interference.

Let's say Alice and Bob have entangled spins in the pure state (leaving out the normalization term):

|up>_alice * |down>_bob - |down>_alice * |up>_bob

According to QM, if Alice measures the spin along the z-axis one of the following alternatives will happen:

a) she gets a positive measurement, her spin is in the pure state |up>, Bob's spin is in the pure state |down>, there is no entanglement between the spins

or

b) she gets a negative measurement, her spin is in the pure state |down>, Bob's spin is in the pure state |up>, there is no entanglement between the spins

How do you think this allows for FTL signaling?

<comment><USER8> > How do you think this allows for FTL signaling?

I already told you: with a single particle, it's not possible. But with multiple particles you can tell the difference between a pure state and a mixed state by observing the presence or absence of first-order interference. So to communicate, you send a stream of EPR pairs to Alice and Bob. Alice transmits by either measuring batches of particles or not measuring them, and Bob receives by observing the presence or absence of first-order interference on his end.

Fun fact: I was able to get a patent on this idea :-)

[https://patents.google.com/patent/US7126691B2/en](https://patents.google.com/patent/US7126691B2/en)

<comment><USER9> People get patents for perpetual motion machines as well... Do you really think your idea works?

This is what I think: the quantum state of your entangled pair is a pure state and if you look at the quantum state of the photon sent to the "receiver" it is described by the density matrix obtained by tracing out the other photon :

      1/2  0
       0  1/2

If you measure in the "transmiter" the horizontal polarization, what you get in the "receiver" is a 50/50 mixture of pure states |H> and |V> which is described by the same density matrix.

If you measure in the "transmiter" the 45-degrees polarization, what you get in the "receiver" is a 50/50 mixture of pure states |45> and |-45> which is again described by the same density matrix.

No matter what yo do or do not measure at the "transmiter" you will get the same measurements at the "receiver" because the density matrix describing the state is always the same (unpolarized light).

<comment><USER8> > Do you really think your idea works?

Of course not. That's the whole point.

<comment><USER9> I'm lost. It doesn't work according to QM. And you agree that it doesn't work. How does it pose a problem for QM again?

<comment><USER8> I never said it did. I said that _if_ you can transform a mixed state into a pure state then _that_ poses a problem for QM because it would lead to FTL signaling. But you can't, so it doesn't.

<comment><USER9> Every time you do your measurement in the "transmiter" you will have a pure state in the receiver and it doesn't lead to FTL signaling.

What you have when you repeat the procedure is an ensemble of states: half of them the pure state |H> and half of them the pure state |V> (or half of them |H> and half of them |V>).

There is no entanglement, only (a mixture of) pure states. And it doesn't lead to FTL signaling.

At the end of the "teleporting" procedure you have a pure state B which is identical to the original pure state C. And it doesn't lead to FTL signaling.

Maybe your problem arises from the following misunderstanding:

> If you could cause an entangled particle to become unentangled (i.e. to > transition from a mixed state to a pure state)

In the example I gave above, the density matrix for the photon arriving at the "detector" doesn't change when the measurement is made at the "transmitter" and entanglement is broken. But the same density matrix describes different situations. When there is entanglement the photon is part of a pure state and the density matrix is obtained by tracing out the rest of the system. Later there is no entanglement and the density matrix describes a statistical mixture of pure states (50% |H> and 50% |V>, or whichever is the apropriate basis for the measurement that was made on the other photon destroying entanglement).

<comment><USER8> Are you distinguishing between a "mixed state" and an "ensemble" and a "mixture of pure states"? Because AFAIK these are all the same thing. If you think they are different, what distinguishes them?

If you agree that they are all the same, then what you are saying is exactly the same as what I am saying, except for the "no entanglement" part. Whether or not you have entanglement or a mixed state depends on what point of view you choose to take. If you have an EPR state, then the joint system is in a pure state, but each individual particle is in a mixed state when viewed as an isolated system. That is what a mixed state _is_. A mixed state is nothing more or less than the state of a proper subset of an entangled system.

<comment><USER9> A mixed state can be produced as a subset of a entangled system. It can also be produced as a mixture of pure independent states. They need not correspond to the same physical situation: you can prepare the same mixture state in different ways. But these ensembles can not be distinguished later (unless you "remember" the lost information about the precise state for each element!).

For example, you can get unpolarized light as a mixture of left- and right- polarized light, or as a mixture of horizontal- and vertical-polarized light, or getting one photon from entangled pairs (and discarding the other). I'm sure that you can find a way to describe that as an entanglement with something else, but there is no need to do so.

In particular, when Alice measures a photon in an entangled pair the entanglement is broken. Bob's photon is no longer entangled with Alice's photon. Hopefully you will agree that Alice's photon is now in a pure state. Again, you may want to make things much more difficult but it's not required to prevent FTL signaling.

<comment><USER8> > I'm sure that you can find a way to describe that as an entanglement with > something else, but there is no need to do so.

That depends on your goals. If all you care about is making correct predictions of experimental results, then yes, one point of view is as good as another.

But if you care about actually understanding what is going on then explaining measurement in terms of entanglement is progress.

> when Alice measures a photon in an entangled pair the entanglement is broken

No. The entanglement remains, and is incorporated into a (much) larger system of mutually entangled particles, including Alice herself. As part of this process, decoherence happens, which makes the original entanglement impossible to detect as a practical matter. But it doesn't go away.

> Hopefully you will agree that Alice's photon is now in a pure state.

No, I will not agree. When Alice measures the photon, the photon must be absorbed by some detector, and so can longer be said to exist at all in any meaningful sense.

<comment><USER9> Fine, but this approach leads nowhere. Before you said that "Before teleportation C is in a pure state". But that's surely impossible, because wherever C is coming from it's entangled with a gazillion things already... If the original state C can be "pure", then the final state B can be "pure" as well (and identical to C).

I think you have a problem with the probabilistic nature of QM, if you only can accept a statistical mixture as being part of an entangled pure system. FTL signaling is just a excuse (and you don't explain how standard QM would allow for it).

<comment><USER8> > this approach leads nowhere.

It has led to a great deal of mental clarity for me. YMMV.

> Before you said that "Before teleportation C is in a pure state". But thats > surely impossible, because wherever C is coming from it's entangled with a > gazillion things already...

That's right, and indeed figuring out how a laser actually works is quite challenging.

[http://blog.rongarret.info/2018/05/a-quantum-mechanics- puzzl...](http://blog.rongarret.info/2018/05/a-quantum-mechanics-puzzle.html)

[https://blog.rongarret.info/2018/05/a-quantum-mechanics- puzz...](https://blog.rongarret.info/2018/05/a-quantum-mechanics-puzzle-part- deux.html)

[https://blog.rongarret.info/2018/05/a-quantum-mechanics- puzz...](https://blog.rongarret.info/2018/05/a-quantum-mechanics-puzzle-part- drei.html)

> If the original state C can be "pure", then the final state B can be "pure" > as well (and identical to C).

Only if you are willing to explain how B was transformed from its initial state into its final state, and more to the point, _when_ this transition happened.

> I think you have a problem with the probabilistic nature of QM

Huh? What have I said that leads you to believe that? It's not true.

> if you only can accept a statistical mixture as being part of an entangled > pure system

That has more to do with philosophy than physics. Does an apple really fall because gravity is pulling down on it? No, but it's a good enough approximation to the truth that it's usually not worth quibbling over.

<comment><USER9> > how B was transformed from its initial state into its final state, and more > to the point, when this transition happened.

There is a full description here: [https://en.wikipedia.org/wiki/Quantum_teleportation#Formal_p...](https://en.wikipedia.org/wiki/Quantum_teleportation#Formal_presentation)

It's difficult to copy formulas here but essentially A and B are in one Bell state at the beginning.

When Alice makes a measurement in the basis of the Bell states for C and A, the result is that B will now be in one of the states

      alpha|0> + beta|1>
      alpha|0> - beta|1>
      beta|0> + alpha|1>
      beta|0> - alpha|1>

Alice knows which one of the four is the pure state of B after the measurement and tells Bob how to rotate the state (if needed) to recover alpha|0> \+ beta|1>

So, again, when Alice does the measurement the state becomes one of the four listed states and when Bob rotates the state (if needed) B is the same state that C was originally. Maybe you agree that this is making correct predictions of experimental results, maybe not. I still don't know when and how does B change along the procedure according to your view.

> No, but it's a good enough approximation to the truth that it's usually not > worth quibbling over.

Talking about "pure" states after a measurement is a good enough approximation to the truth, but you find it worth quibbling over :-)

<comment><USER8> > When Alice makes a measurement in the basis of the Bell states for C and A, > the result is that B will now be in one of the states...

The problem with that description is that the word "now" is not well defined when Alice and Bob are far apart.

> but you find it worth quibbling over

Well, yeah. Just because I'm willing to accept an approximation to the truth doesn't mean I stop caring about the actual truth.

<comment><USER9> > The problem with that description is that the word "now" is not well defined > when Alice and Bob are far apart.

Do you have an alternative description to work around this "problem"?

QM is a non-relativistic theory. In this case, the measurement on C/A is strictly before the rotation on B so there is not even the shadow of a problem. Relativistic extensions to QM are Lorentz-invariant and for space- separated observables there is a restriction for operators to be commuting (so the outcome is consistent with either of the observations being "first").

<comment><USER8> > Do you have an alternative description to work around this "problem"?

I like this approach:

[https://arxiv.org/abs/quant-ph/9605002](https://arxiv.org/abs/quant- ph/9605002)

> the measurement on C/A is strictly before the rotation on B so there is not > even the shadow of a problem

Yes, obviously. That is not what I'm talking about.

Consider this variation on the theme: Alice and Bob share N>>1 entangled A-B pairs. Alice prepares N additional C particles, all in a known pure state P, and runs them all through the teleportation protocol. But instead of sending Bob rotation instructions, she sends him only the serial numbers of the particles that do not require Bob to perform a rotation. Bob keeps the particles corresponding to those serial numbers, and destroys the rest. I presume you will agree that Bob now has a collection of approximately N/4 particles in a pure state P. (I do not agree with this, BTW, but I accept it here for the sake of argument.)

Now imagine that Bob simply selects N/4 particles at random without any information from Alice. He has no idea what Alice has done on her end, or indeed if she has done anything at all. There are now three cases:

1\. Alice has performed her measurements, and by pure chance Bob has selected the same set of particles that Alice would have told him to select. I presume that in this case you would agree that this set of particles is still in state P. (The odds of this happening are, of course, vanishingly small, but still >0, and this is a thought experiment.)

2\. Alice has NOT performed any measurements. Are Bob's particles still in state P?

3\. Alice has performed measurements, and Bob's random selection does not match Alice's list of particles that don't require rotation. (This is the overwhelmingly likely scenario, of course.) In this case, Bob's particles are not in state P (because 3/4 of them require a rotation). But are they in some _other_ pure state Q?

The answer to 2 and 3 must be "yes" if you want to avoid FTL (because otherwise Bob could determine whether or not Alice has performed measurements). So the conclusion is: if you randomly select N/4 particles from a mixed population, the resulting particles are all in some pure state. Do you agree with this? If so, were those particles in that same pure state before they were selected?

The conclusion I'm driving towards is that purity of state has nothing to do with the actual physical situation, it's a matter of _perspective_. Any physical state can appear to be pure if you look at it in the right way, but finding the "right way" to look requires additional information, i.e. information from Alice. Nothing Alice does changes anything about the physical situation on Bob's side. It simply produces the information Bob needs in order to look at his particles in the "right way" to see a particular pure state.

<comment><USER9> I thought you were referring to the relativity of simultaneity. I'm glad you insist on the FTL communication issue, maybe now I will be able to convince you that there is no issue at all...

> The answer to 2 and 3 must be "yes" if you want to avoid FTL (because > otherwise Bob could determine whether or not Alice has performed > measurements).

The answer to 2 is "no". If Alice has not performed any measurement, the N "B" particles that Bob has are not in a pure state. They are a subsystem of the N (indentical) entangled pairs formed by the N "A" particles that Alice has plus the corresponding N "B" particles that Bob has (let's call that state E).

So, depending on whether Alice has done the measurement or not, what we have is (I undertstand you don't really accept this description, it's for the sake of the argument where you will try to show how this description is unacceptable):

      Measurement not done
      Pairs remain entangled
      The N particles held by Bob are not in a pure state
      (The A/B pairs are in a pure state E)

      Measurement done
      Pairs are no longer entangled
      The N particles held by Bob are each in one definite state P or P' or P'' or P'''
      (Alice knows the precise state of Bob's particles, she knows how to rotate each particle to get the state P)

You say that, before any message from Alice can reach Bob, he can determine wheter or not she has performed the measurement.

Can you explain how? (Hint: no, you cannot.)

<comment><USER8> > I thought you were referring to the relativity of simultaneity.

Yes, I was.

> I'm glad you insist on the FTL communication issue,

It amounts to the same thing.

> maybe now I will be able to convince you that there is no issue at all...

Maybe, except that I'm not sure you're clear on what we're actually disagreeing about.

> You say that, before any message from Alice can reach Bob, he can determine > wheter or not she has performed the measurement.

Only in a hypothetical case, not realizable in practice (probably -- see below), where Bob has chosen N/4 particles at random and those just happen to coincide with the particles that Alice measured and found to require no rotation. In that case, Bob will, on your view, observe first-order interference if Alice has measured, and not otherwise.

Maybe it would help if I describe it as a detailed thought experiment. The experiment takes place in four phases.

Phase 1: Alice and Bob choose a basis for a pure state P which they will use for the remaining two phases.

Phase 2: Alice teleports N copies of state P to Bob using the normal protocol, including the transmission of the results of her measurements. Bob takes the N/4 particles that require no rotation and tests them to see if they produce first-order interference relative to the basis of P. I trust you and I agree that he will observe interference in this case.

Phase 3:

This is the part that can't be realized in practice, and I have to number the steps here because this phase runs in a loop. Phase 3 is designed to answer the question: what would have happened in phase 2 if Bob had chosen the same N/4 particles by pure chance? So...

1\. N EPR pairs are distributed.

2\. Alice performs her part of the teleportation protocol, but does NOT tell Bob the results of her measurements.

3\. Bob selects N/4 particles at random and tests for first-order interference relative to P. (The vast majority of the time the result will be negative.)

4\. Bob and Alice compare Bob's random selections in step 3 with the results of Alice's measurements in step 2. If they happen to coincide, i.e. Bob just happened to pick the correct N/4 particles that did not require rotation, the experiment halts, with the result being whatever Bob observed on the last iteration of step 3.

I trust that you and I will agree that Bob will also observe interference in this case.

Phase 4 (this is the interesting one):

This is identical to phase 3, except that steps 2 and 3 are reversed, i.e. Bob makes his random selection and interference measurement BEFORE (in a fully relativistic sense) Alice makes her measurements. i.e.:

1\. N EPR pairs are distributed.

2\. Bob selects N/4 particles at random and tests for first-order interference relative to P.

3\. Bob communicates to Alice that he is done.

4\. AFTER Alice receives Bob's signal from step 3, she performs her side of the teleportation protocol for N copies of P.

5\. They compare the results of Alice's measurements in step 4 with Bob's random choices made in step 2. If they coincide (i.e. Bob just happened to choose the correct N/4 particles that did not require rotation) the experiment concludes, with the result being whatever Bob observed on the final iteration of step 2. Otherwise, they go to step 1 and try again.

On your view, the predicted result of phase 4 will be negative. So if Alice cheats and performs her measurements before receiving Bob's signal, Bob can tell.

Postscript: now that I think about it, it might actually be possible to perform this experiment. A mach-zehnder interferometer can be pretty sensitive, so it might be possible to get N down low enough that the experiment could terminate in a reasonable amount of time.

<comment><USER9> > I'm not sure you're clear on what we're actually disagreeing about.

To be clear, I disagree with your claim that the QM description is not correct because it leads to FTL communication.

If you stand by that, you're wrong. If that's not what you meant, then there is no disagreement.

Now, if I understand your latest comment, you say that it's "Only in a hypothetical case [...] where Bob has chosen N/4 particles at random and those just happen to coincide with the particles that Alice measured."

This is like saying that two standard 52-card decks can be used for FTL communication, in the hypothetical case where Bob picks the same card that Aliced picked. If you think that is FTL communication I cannot agree with that. This kind of "FTL communication" doesn't present any problem at all for the QM description.

Maybe I'm missing something, but I don't see in your description of the experiment any trace of potential FTL communication. You're not even trying! I would like to see something like the following (but I understand you cannot provide it, because it's impossible):

1) N EPR pairs are distributed

2) Bob does something ("selects N/4 particles at random and tests for first- order interference relative to P" or whatever) and concludes that "Alice has done something to her particles" or "Alice has not done anything to her particles" depending on the result of his measurement.

[The prediction is done at this point, the verification step follows.]

3) Alice tells Bob if she did or not measure her particles before he did. Or Bob tells Alice his prediction. Or Alice and Bob tell Charlie and he performs the check. In any case, this requires slower-than-light communication.

This experiment can be repeated several times to see if Bob's prediction is right every time or if at least there is some correlation between what Alice did and what Bob guessed.

Your description has additional steps involving communication between Alice and Bob before there is any result or prediction. It is not in any way incompatible with the standard QM formulation that you reject, as far as I can see.

It looks like if, in the card-picking example, Bob picks a card and then compares his card with Alice's card. If the card is the same they announce that FTL communication had been achieved. If the card is not the same, they try again. If you think this is not a fair characterisation, please make clear what prediction is Bob doing before communicating with Alice.

To make my point as clear as I can once again: according to QM, Bob cannot tell if Alice has performed or not a measurement on her side. For any measurement that Bob can do on his particle, the predicted distribution of outcomes conditional on "the entanglement is broken, the particle is now in an unknown pure state" is exactly the same as the predicted distribution of outcomes conditional on "the entanglement is intact, the particle is not in a pure state (the pair A/B is still in the pure state E)". Whatever the outcome he gets out of his measurement, it cannot be evidence for one or the other.

<comment><USER8> > your claim that the QM description is not correct

That's not my claim. My claim is that the change in the _mathematical_ description of Bob's particles (from mixed states to pure states) when Alice measures her particles does not correspond to any actual physical change in Bob's particles.

We agree about the math, and we agree about the outcomes of all experiments performed by Alice and Bob.

There is one thing we disagree about, and that is the outcome of the thought experiment I described above (which may in fact be realizable in practice). I predict that you will observe "retrocausality" in phase 4, i.e. when the experiment halts, Bob's choices will correspond with Alice's measurements with (essentially) 100% certainty. (Of course, this isn't really retrocausality, but it appears that way.) AFAICT, on your view of the world, you would predict (essentially) a 0% chance of Bob's choices corresponding with Alice's measurements.

Just out of curiosity, are you a physicist? Because you obviously know what you're talking about.

BTW, just in case it wasn't obvious, I left out a detail in the description of the thought experiment: In phase 3, if the experiment does not halt at step 4 it loops back around to step 1, just as it does in phase 4.

<comment><USER9> >> your claim that the QM description is not correct

> That's not my claim. My claim is that the change in the mathematical > description of Bob's particles (from mixed states to pure states) when Alice > measures her particles does not correspond to any actual physical change in > Bob's particles.

Well, according to quantum mechanics there is a physical change when Alice measures her particles because:

before Alice's measurement => the pair "A/B" is entangled

after Alice's measurement => the pair "A/B" is not entangled

According to you alternative description, is the pair A/B entangled or not after Alice's measurement? Or is entanglement not an actual physical property of the pair?

I am (or used to be, for a brief time many years ago) a physicist. We had the opportunity to discuss in person last week. I enjoyed that (and this) discussion, thanks. By the way, I said I would send you a comment from David Mermin about the recent paper from Frauchiger and Renner. Actually I was thinking about this article from Jeffrey Bub: [https://arxiv.org/abs/1804.03267](https://arxiv.org/abs/1804.03267)

<comment><USER8> Oh, Hi! Sorry, I didn't recognize you.

> Well, according to quantum mechanics there is a physical change when Alice > measures her particles because: > before Alice's measurement => the pair > "A/B" is entangled > after Alice's measurement => the pair "A/B" is not > entangled

No. That's the whole point. The presence of absence of entanglement is a function of the perspective you choose to take when modeling the situation, not a function of the actual physical situation.

Thanks for the pointer to the Bub paper, that's a great reference.

Maybe we should move this discussion to email? It's getting pretty deeply nested and I don't think anyone else is paying attention.

<comment><USER9> There goes my HN anonymity! (Not a big deal, but if you can edit it out I prefer it, just in case...)

I have some follow up comments, I'll send you an email when I have time to write something detailed.

</comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER10> Papers like this are so terse.

I understand the need to use correct verbiage; but to the layman, this is incomprehensible.

<comment><USER2> With all due respect, these papers are not written for the layman. They are written for the few thousand people who work in the field or near enough to understand this work. Single results in physics (and science) in general are almost never individually relevant to the public. The public should read either review or meta papers, or they should read the articles/books written by scientists for public consumption. As a physicist, I rarely upvote physics papers on HN, unless there is insightful commentary in the comments.

This is not an insult to anyone who is not a scientist - just that jargon is necessary for rapid progress, and understanding jargon requires developing expertise by many years of work.

<comment><USER11> I think OP was questioning how is this paper fits in an generalist IT/business forum.

<comment><USER2> I totally agree with them that it should not be posted here.

</comment></comment></comment></comment><comment><USER12> Do I get this straight: "Quantum teleportation" is like receiving a letter with four pages and then telling another receiver of the same letter which page to read?

<comment><USER9> With the caveat that the four pages in Bob's letter are not written until Alice does her thing with her copy of the letter and the photon she wants to "teleport". Note also that she doesn't know the state of the photon, which is destroyed as a result of the procedure.

</comment></comment><comment><USER13> it begins

</comment><comment><USER14> Is this not the holy grail?

<comment><USER15> The holy grail of what?

</comment></comment><comment><USER11> It's not surprising that the article is in English even though it's an all- Chinese team, because it was published on an English journal. But I can't stop wondering how many years are left before most scientific output is in Chinese. The dominance of English might be over soon.

<comment><USER2> It took centuries of British colonization to make British English the lingua franca of the world, and decades of American cultural and economic imperialism to switch the default to American English. It is unlikely that a complete switch to Chinese will happen on any shorter scale, if ever.

<comment><USER16> Decades aren't really a long scale, though. 3 decades ago almost nobody in the Czech Republic spoke any English, today it's a common day-to-day language in Prague as many foreigners live there, even the homeless speak good English.</comment></comment></comment>


Is the Internet about to get sloooooow? - <AUTHOR> http://www.cnn.com/2014/09/10/opinion/van-schewick-internet-slowdown/index.html

<comment><AUTHOR> The title for this post is regrettable, but op-ed authors often don't choose their own headlines.

Despite the title, the article is well worth reading. Barbara von Schewick is one of the leading thinkers on net neutrality and understands the underlying issues better than almost anyone out there.</comment>


RETAILERS: Best Shopping Engines for Retailers [New Research / Infographic] - <AUTHOR> http://www.godatafeed.com/digital-shelf-solutions/infographic-best-shopping-engines-for-retailers?utm_source=embed&utm_medium=blog&utm_campaign=infographic

<comment><AUTHOR> Contains new research data compiled by GoDataFeed on Product Listing Ads, Marketplaces and Comparison Shopping Engines - which have the largest user bases. Some insights into where shoppers spend the most.</comment>


Exxo – build portable Python binaries - <AUTHOR> https://github.com/mbachry/exxo/ <comment><USER2> > Although exxo binary itself is statically linked, included C extensions (if > any) are not. All required shared libraries must be installed on the target > machine. For example, if you use lxml, you must install libxml2.

This is a major shortcoming. It means, e.g. that an app with a PyQt or Wx GUI requires those to be installed on the target system, at the expected level. PyInstaller, cxfreeze, etc. bundle all dependencies into the frozen app making it really independent of the receiving environment. Identifying all those dependencies at build time is _highly_ nontrivial, and packaging them so that the Python import statements work at run-time is even less so.

</comment><comment><USER3> I love that this comes with an apt-get line telling you exactly what you need to install to get running. Every project should do this.

</comment><comment><USER4> Great, but it's not clear how this is different from several other Python packagers like Pyinstaller. Any clues?

<comment><USER5> Seems comparable to Twitter's PEX: a relocatable venv with custom entry points to act as a binary. PEX also takes the zip approach but allows for not zip safe libraries by unpacking to a directory before running.

</comment></comment><comment><USER6> I like the approach taken here - pants/PEX is a bit of a monster (no offense intended - it's a very smart monster, but a monster nonetheless).

I'm glad to see projects taking a simpler approach to zip apps - pants makes sense if you're trying to package legacy apps with huge sets of dependencies, but it's overkill for smaller apps.

However, the author needs to add some test coverage before I'd feel comfortable contributing or using it.

</comment><comment><USER7> > _" Because your application is run as zipapp, it must be zip safe. ... The > main violation against zip safety is using filesystem API..."_

I like everything about this, except for the possibility that zipapp constraints could haunt me.

</comment><comment><USER8> In what sense is it meant that this is 'portable' it says they only support Linux on x64.

<comment><AUTHOR> The word portable isn't limited to architecture. If you've ever tried to build software with Python and distribute it in a simple way (a-la go, or a Java .jar) it's not easy. This (and others mentioned below, like PEX) aim to make shipping Python app "binaries" around simple, regardless of OS or system Python presence

<comment><USER9> It IS easy. You can just tell people to `pip install --user your_app` and use it (might need $PATH correction). All Linux distros ship with Python, and if pip is not available, it can be installed easily.

Or you can build and ship .rpm/.deb packages if you feel like it.</comment></comment></comment>


Einstein was right all along: the future is dark - <AUTHOR> http://www.smh.com.au/technology/sci-tech/einstein-was-right-all-along-the-future-is-dark-20110519-1ev1x.html

<comment><USER2> The astronomy department at Swinburne that did this research do excellent public lectures every month covering topics such as these in depth by the scientists doing the research.

<http://astronomy.swin.edu.au/outreach/?topic=freelectures>

</comment><comment><USER3> This article is misleading in a couple of ways.

First, Einstein favored a static universe. He also really hated the very idea of a cosmological constant, but it was needed for the whole model to make sense. In retrospect it was a classical example of someone not accepting what the math was telling him, on account of personal prejudice.

Second, the article makes it sound like cosmic expansion is a new observation and that it somehow vindicates Einstein. In fact, we've been using red shift- based calculations for a very long time to reliably determine very large distances.

And contrary to what the article says, matter is not "pushed" apart. That's not how cosmic expansion works. _New space_ is being created all around us, all the time. It's just like all cosmic distances are continually scaled up. There is no inertia involved, and that's also the reason why some day parts of the universe will be able to recede from us faster than the speed of light.</comment>


How not to benchmark Cassandra: a case study - <AUTHOR> http://www.datastax.com/dev/blog/how-not-to-benchmark-cassandra-a-case-study

<comment><USER2> I find the language regarding synchronously durable writes to be confusing. Writing to the filesystem and invoking fsync every 10 seconds is not synchronously durable. You still send a response before the data hits non- volatile media. In my mind that would make the MongoDB, Couchbase, and Cassandra behaviors roughly equivalent barring differences in the frequency with which data is synced.

Writing to the filesystem (without syncing) is a few hairs better than buffering in application memory, but then you are at the mercy of the filesystem blocking your party for a few hundred millis while it naval gazes at random. Not a huge deal for most workloads because you can still get great latency at 99 and 99.9, but beyond that it's a problem.

Not standardizing on a specific set of commit log behavior (sync vs async, fsync frequency) is pretty egregious for benchmarking anything with a log.

It's not clear from the blog post which direction you went in, relaxing durability in Cassandra or increasing durability in the others. I had to go to github to figure out that you switched to synchronous commits all around. That begs the question, were there other tunables necessary to make synchronous durability perform well? I know in some databases you can set how long the database will wait to group commit in terms of # of transactions and time.

Having a working group commit implementation is of course very important.

<comment><USER3> This was the toughest part to make clear as well as brief. I was not entirely successful.

For Cassandra I used the default 50ms batch window. I'm not aware of tunable windows for the others.

</comment></comment><comment><USER4> I think it's important to consider that people interpreting benchmarks need to be skeptical and aware of the scope of the results: a lot of problems are as much from people overgeneralising results as from bad experimental methodology.

</comment><comment><USER5> All I see are graphs with no units on the Y axis.

<comment><USER3> They are all ops/s.

<comment><USER6> Hi, I think the point is that the graphs need Y-axis labels to be meaningful.</comment></comment></comment>


RIAA fires MediaSentry - <AUTHOR> http://news.cnet.com/8301-1023_3-10130785-93.html

<comment><USER2> Does the RIAA have someone new in management? I'm surprised by the about face they've had recently; They stopped suing downloaders, and now they're firing their detective agency that gathered evidence for them.</comment>


It's time to publicly shame United Airlines' so-called online security - <AUTHOR> https://techcrunch.com/2016/08/13/its-time-to-publicly-shame-united-airlines-so-called-online-security/?ncid=rss <comment><USER2> Yeah, this is terrible. I ended up picking random answers and storing them in LastPass on the note for my account.

The whole experience is hostile to users, and probably pretty euro / western - centric. I don't know how they localized the list, but I would be really surprised if they got everybody's possible responses to favorite music genre and whatever in there.

And, of course, using PUBLIC information about people as a security feature is beyond stupid. If your okcupid profile helps me hack your account, I don't think that counts as "two factor".</comment>


You Can Now Call Into Google+ From Regular Phones - <AUTHOR> http://www.disruptivetelephony.com/2013/05/you-can-now-call-into-google-from-regular-phones-google-connects-google-voice-to-hangouts.html

<comment><USER3> It's been this way with Talk and GMail for a long time. Someone calls my GV number and if GMail is open, it rings in GMail.

<comment><USER4> You are absolutely right. I've been using GV as my general number since 2009 and I do not recall this feature not being there. It is quite handy for me when I'm overseas - not paying any roaming charges to make/receive calls - <USER2> there is nothing new or disruptive in this.

<comment><USER5> If I'm not mistaken the conversion of Talk to Hangouts last week dropped this feature, and it's only now rolling back out as part of Hangouts.

<comment><USER6> I answered multiple calls last week in a Hangout that opened itself from my Gmail when the call came in.

</comment></comment></comment></comment><comment><USER7> I don't know about others, but I don't know I like this change over previous Google Talk implementation receiving a phone call.

Being able to receive a call on Hangouts is great, but having a somewhat underpowered machine, it takes me about 10 to 15 seconds loading up full Hangouts session. (presuming, with everything including video chat components) By the time the session is loaded, the call is often already sent to voice mail, or caller would have given up on me.

I think Hangout is a great system in the situation where you are actually setting up to have one -- but not so great for responding to unexpected calls.

It wouldn't be so bad if responding to the call would actually answer a call immediately, but the way it is currently implemented, I don't think it's usable...

<comment><AUTHOR> Yes, I wish there was a way to turn OFF the video component of Hangouts when receiving a call via Google Voice. On one of my systems the launch of Hangouts does take a few seconds - and that seems to be largely related to bringing up the video component.

</comment></comment><comment><USER8> Hack: You can still make outgoing calls using Google Voice/Hangouts

1\. In Gmail type in _your_ name into the "start a hangout" box 2\. In Hangout window click on "add telephone". 3\. type in phone number you want to call. 4\. Call.

<comment><USER9> Or just click on the "Call Phone" button next to the "Start Hangout" button in Gmail? That's still there for me, is it not for other people?

<comment><USER10> > Or just click on the "Call Phone" button next to the "Start Hangout" button > in Gmail? That's still there for me, is it not for other people?

Its not there for me, and Google has _acknowledged_ that the outbound call functionality is missing with Hangouts and that that is _why_ the legacy Talk interface is still available and you can freely switch between them, saying that they will retain that interface until the calling features have been integrated into Hangouts. [1] So I don't know why you're special.

[1] [http://www.theverge.com/2013/5/20/4348256/hangouts-is- future...](http://www.theverge.com/2013/5/20/4348256/hangouts-is-future-of- google-voice-gmail-calls-returning-soon)

</comment></comment></comment><comment><USER11> So some conjecture:

I can't understand why Google doesn't do SIP or even a full telecom play. The only answer I can come up with is that they don't think the business is worth the extra regulatory scrutiny.

Sidenote: Dan is awesome. If you're into Telephony and you don't read his stuff you're making a mistake.

<comment><USER12> I'd suspect they don't want to get AT&T'd

a lá <http://en.wikipedia.org/wiki/Bell_System_divestiture>

<comment><USER13> How is that relevant? They don't own the entire network and it wouldn't make them a monopoly natural or otherwise.

<comment><USER12> brain fart. I was thinking monopolies and came up with att when microsoft (re IE) would be a better example.

</comment></comment></comment></comment><comment><USER14> I had this happen to me twice, and in both instances the call did not ring my telephone.

Clearly some kinks to work out.

<comment><USER15> Did you answer in Hangouts?

I find it rings my computer a bit before it rings my phone. I'm not sure if my phone ring had the same latency it would have if I were not logged in on my computer.

<comment><USER16> I just tried it and it only rang my computer.

When I quit hangouts from my computer it did not ring my phone and directed me to the voice mail after a couple of dial tones.

A normal hangout call from someone else using hangouts rings both at just about the same time (sometimes a lag on the phone).

</comment></comment></comment><comment><USER17> A mobile phone that can do local voicemail and with that avoid the Telco's getting paid twice for a call would be an area I'd like to see fixed first.

Still awaiting google voice for the UK, one day maybe.

</comment><comment><USER18> I wonder if this will work with hangouts on phones. For instance if I call someone who also has GV, would I be able to hop into a video call seamlessly.

<comment><USER19> That might be why Hangouts requires confirming your phone number on installation.

</comment></comment><comment><USER20> What's new about this? Prior to Hangouts, calls to my Google Voice number always was routed to my cell phones and Google Talk.

<comment><USER10> > What's new about this? Prior to Hangouts, calls to my Google Voice number > always was routed to my cell phones and Google Talk.

As I understand, both inbound and outbound calling via the Gmail interface were nonfunctional initially for users who upgraded to Hangouts, so the "new" thing is that the inbound call functionality was restored; outbound is still pending (and it sounds like they are planning, ultimately, much deeper integration than just restoring what the old Gmail Talk interface had.)

</comment></comment><comment><USER6> No, you've been able to do this.... for years. And yes, it's worked consistently since they launched Hangouts. I _often_ answer calls in Gmail and they have since simply began opening in Hangouts through Gmail.

Works perfectly, no idea why "the dialer went away" means "incoming calls no longer work", but hey, it's Google and it's FUD, should I bother trying to be surprised?

Don't get me wrong, Google fucked their one big chance to integrate Voice, Video, SMS and IM. With Hangouts, I should be able to "Call Someone" and have it negotiate video if we both have and want video, or it should use the next available medium. If both users use Hangouts, then send a Hangout IM. And if not, finally fall back to Google Voice/VoIp/SMS.

The users shouldn't have to ask themselves, "wait, does Bobby have Hangouts?" ever. That is literally the number one issue with G+!

<comment><USER21> Bothers me to no end that Apple does this same shit with FaceTime, presumably to appease the carriers. They already bypass SMS when both are iMessage users - why the hell are they not doing video calls by default when both have cameras?

<comment><USER10> > Bothers me to no end that Apple does this same shit with FaceTime, > presumably to appease the carriers. They already bypass SMS when both are > iMessage users - why the hell are they not doing video calls by default when > both have cameras?

Because, _first_ , most people don't prefer video calls in many circumstances (leaving aside cost issues), and second because of cost/performance issues, since voice calls use voice minutes and video calls would use data, and most users are more likely to face data overages (or, if on quasi-unlimited plans, hit the point of data slowdowns) than they are to run out of plan voice minutes.</comment></comment></comment>


Ask HN: Is iphone 4's gyroscope magical? - <AUTHOR>

Though Steve Jobs termed the Gyroscope magical and awesome, was it truly a new feature?<p>I tried this. Opened Google Maps on Samsung Spica, zoomed in into New York map, switched to street view and turned on the compass mode.
Voila!
It seems to do the same thing as in the "awesome" demo from Jobs. Rotate the phone around yourself, the 360 degree views also rotates. Try this on your Android.
Though, it need not be the exact same thing technology wise, but it "seems" to do the same thing. <comment><USER2> Combine gyroscope, accelerometer and compass, and you get very precise data about movement of the device. Together they basically enables you to do very interesting motion control stuff. Think an always-with-you Wii controller, but better.

I bet that there will be a lot of cool innovations coming. In the beginning, they will be mostly games, but it will be usable for many kinds of real world control tasks, too.

(More info about gyroscope [http://forums.appleinsider.com/showthread.php?threadid=11060...](http://forums.appleinsider.com/showthread.php?threadid=110603))

<comment><AUTHOR> That clears my doubts on the gyroscope. This does open ground for a lot of innovation.</comment></comment>


SpaceX Falcon 9 Lander (game) - <AUTHOR> https://scratch.mit.edu/projects/76866912/ <comment><USER2> Extremely very not easy. And also small, Flash-based, ugly to look at, and frustrating. But it's certainly addictive.

</comment><comment><USER3> 47 tries and I got it to land once, clearly through luck.</comment>


Tell HN: I think Kotlin is great - <AUTHOR> I think Kotlin programming language is great. :) <comment><USER2> It's better to link to the page of the language, or to a good tutorial.

My first question is: What makes this language different from all the other languages? (Something more specific than great.)

I'll copy partially a comment by Matthew Butterick in the Racket mailing list. [https://groups.google.com/forum/#!msg/racket- users/oS_D2OHuF...](https://groups.google.com/forum/#!msg/racket- users/oS_D2OHuFI4/_gDy9lo0AQAJ)

It can provide some ideas:

>> So, what is the best way [to promote Racket]?

> Here's one good way to promote the language:

> 1) Make something impressive with Racket.

> 2) When someone asks "how did you make that?" give Racket all the credit.

> Don't cut corners in step (1).

Do you know an interesting project made in Kotlin?</comment>


Rubbish (2002) - <AUTHOR> http://www.wweek.com/portland/article-1616-rubbish.html-2 <comment><USER2> There is a long standing constitutional interpretation that your garbage, once put on the street, is not protected by the Fourth Amendment.

<comment><USER3> The state constitution and precedent based on it may provide additional protections that the federal one does not. (It does in Washington, for instance, as the city of Seattle learned when they tried to inspect people's garbage and fine them for not recycling or composting.) I'm not familiar with the nature of the situation in Oregon.

<comment><USER4> FTFA:

> The U.S. Supreme Court has held that the Constitution gives you no privacy > rights over your garbage, but individual state constitutions can offer more > stringent privacy rights. Warrantless trash searches by police are not legal > in Vermont and New Jersey.

</comment></comment></comment><comment><USER5> When someone says they don't mind surveillance and have "nothing to hide", ask them for the password to their primary email. Most people simply don't think through the practical implications of their information being sifted through.

<comment><USER4> Indeed, this is exactly the topic of the OP article.

They mean _you_ have nothing to hide _form them_. They still insiste upon their own privacy:

> "Things inside your house are to be guarded," [Police Chief Kroeker] told > WW. "Those that are in the trash are open for trash men and pickers and--and > police. And so it's not a matter of privacy anymore."

> Hours later, the chief issued a press release complaining that WW had gone > through "my personal garbage at my home." KATU promptly took to the airwaves > declaring, "Kroeker wants Willamette Week to stay out of his garbage."

> A few moments later, [the mayor's] office issued a prepared statement. "I > consider Willamette Week's actions in this matter to be potentially illegal > and absolutely unscrupulous and reprehensible," it read. "I will consider > all my legal options in response to their actions."

</comment></comment><comment><USER6> What will the freegans do if we outlaw trash picking? Not to mention, I've found some awesome working computer parts (1000W ATX power units, with cool looking internal cables, fuck yeah!) and completely reasonable, non-branded, desktop chassis on the side of the road.

Surprising as it is that a blood test for drug use gleaned from one's bio- waste is slightly rotten, maybe it's the vice laws that should be thrown some shade. Fourth amendment, sure, but I think it's worth noting that it's still the burden of the individual to render their discarded waste non- incriminating.

What this means for genetic privacy, finger prints and other powerful personal identifiers (the _what-you-are_ authentication factors), I simply don't have a good answer for.

</comment><comment><USER7> I shred my screwed up tax returns and anything with SSN.

I'm generally not a tin-foil hat wearer, but is it prudent to shred register receipts? Anything else?

<comment><USER8> > but is it prudent to shred register receipts?

I'd say so. First, it makes life more difficult for an attacker who does want to recover sensitive documents (simply: there's a lot more noise from the receipt shreds), and purchase patterns tell a lot about you - in 2012, for example, Target got flak for finding out a girl was pregnant before the girl herself did ([http://www.nytimes.com/2012/02/19/magazine/shopping- habits.h...](http://www.nytimes.com/2012/02/19/magazine/shopping- habits.html?_r=1&hp=&pagewanted=all))... for example while you may decide to take all your whiskey bottles to the recycler, when I see weekly purchases of a dozen Jack Daniels bottles I can assume either you are a heavy drinker, or your family likes to heavily drink. Both stuff I could use as extortion leverage.

I prefer to drop the receipts in the store as I leave the property unless there's something on the receipt on which I might want/need warranty worth more than 50€ - it's not tied to me, the store and anyone present at the property can see what I bought anyway and as I like to pay cash for most things now I don't leave any data in big-data analysis companies which match purchases with my DC account data...

</comment></comment><comment><USER9> I'm reminded of George Orwell's quote:

"Journalism is printing what someone else does not want printed: everything else is public relations."

<comment><USER10> Orwell is wrong, because most of public relations (and propaganda more generally) is printing what _someone_ else does not want printed, too.

<comment><USER11> Orwell isn't wrong in this case... because the quote wasn't Orwell. Who actually came up with it is lost to the mists of time [https://quoteinvestigator.com/2013/01/20/news- suppress/](https://quoteinvestigator.com/2013/01/20/news-suppress/)

Orwell did state a similar notion, "If liberty means anything at all, it means the right to tell people what they do not want to hear", in the preface to Animal Farm.

<comment><USER4> The liberty quote means something quite different, and quite controversial. Contrast against "Freedom of speech does require anyone to listen"

</comment></comment></comment></comment><comment><USER12> Note: this was posted under the much-more-useful subtitle, "Portland's top brass said it was OK to swipe your garbage--so we grabbed theirs".

</comment><comment><USER13> Please put a 2002 tag on this.

</comment><comment><USER14> Published December 23, 2002 Updated December 11, 2017

<comment><USER15> Might have missed it while reading the article, but what was updated?

<comment><USER16> I diff'd the text with a Wayback archive and it appears to be nothing more than minor formatting and sentence structure changes. Nothing of substance.

<comment><USER17> They updated the update date (see also: autometalogolex).

</comment></comment></comment></comment><comment><USER18> >We set it down next to the rest of our haul from District Attorney Mike Schrunk's trash--the remains of Thanksgiving turkey, the mounting stack of his granddaughter's diapers

If they really wanted to make his skin crawl they should have donated them to "Pamperchu" and his friends.

<comment><USER19> Encyclopedia Dramatica informs me Pamperchu has only been around since 2008, six years after this article was published.</comment></comment>


Daily Weigh-In May Help Dieters Lose - <AUTHOR> http://www.webmd.com/diet/news/20051118/daily-weigh-in-may-help-dieters-lose

<comment><USER2> I can confirm this. I weighed myself every morning since the end of December 09 and I have dropped 53.2 pounds (240 lb to 186.8 lb).

Obviously the weighing in didn't make me the lose the weight, it was the reinforcement and the notice of a gradual change (or gradual increase day- over-day) that kept me going with my new eating habits.

</comment><comment><USER3> This is one of the tips espoused by the Hacker's Diet. I used this more than a decade ago to drop 20lbs:

<http://www.fourmilab.ch/hackdiet/www/hackdiet.html>

The concept should be familiar to those in startup land, though: "You Can't Improve What You Don't Measure"

<comment><USER4> Since your day-to-day weight fluctuates, daily weighing wouldn't show you accurate day-to-day improvements properly. My guess is that weighing yourself daily is more about staying focused and engaged; you're constantly checking-in with what you're doing, and more likely to think about it and stick with it.

<comment><USER5> The Hacker's Diet accounts for this by encouraging you to look at a moving average of your daily weight, rather than the number itself:

<http://www.fourmilab.ch/hackdiet/e4/signalnoise.html#Fa73>

</comment></comment></comment><comment><USER6> Weight lose is super simple, I am down 25kg since Jan 2010 following the primal blueprint guidelines: <http://www.marksdailyapple.com>

No gimmicks, no hours of pounding the pavement, no stupid exercise machines, no processed crap food, just eat the right healthy and natural foods and your body will naturally drop down to the right body fat percentage. Plus I can eat heaps of bacon and steak and not feel guilty about it anymore.

This video is fantastic, well worth the 90 minutes to watch it, explains in detail what happens to carbs in your body: [http://www.youtube.com/watch?v=dBnniua6-oM&feature=playe...](http://www.youtube.com/watch?v=dBnniua6-oM&feature=player_embedded)

This is a fantastic movie also, highly recommend you get a copy: <http://www.fathead-movie.com>

</comment><comment><USER7> This is pretty obvious to me, made complicated by people who want super answers or miracle get rich quicks or anything like that. If you see your weight every day and seeing it going up, you eat less. If you see it going down, you get motivated and stay on the same track.

"I lost 20 pounds...How? I drank bear piss and took up fencing. How the fuck you think, son? I exercised."

<comment><USER8> People will probably bite back saying that exercise doesn't correlate with weight loss. That is true, but less important than the ultimate result: _persistent weight loss_. And exercise corresponds damned well with persistent weight loss. Cheers!

</comment></comment><comment><USER9> As a personal anecdote, daily weigh-in was crucial for my (rather humble) weight loss - from 82 to 75 kg in about 12 weeks. I would weigh myself in at the same time - in the morning, before taking in any food or drink, but after taking care of the bodily needs. I never had the need to count the calories, so I have absolutely no idea what my calorie intake was while losing weight compared to normal diet. I do, however, keep a fairly consistent eating regime. So, the daily weigh in results were just used to adjust the size of portions a little bit here and there. It definitely helped.

</comment><comment><USER10> I have no idea if it works or not, but I want to point out two things. 1: It seems that this is a correlation study rather than a causality study. 2: Your weight can fluctuate on a day to day basis, especially depending on what you've eaten recently, how much water you've drank, the time of day, whether you've gone to the bathroom, etc. The overall trend over a larger period of time is what's important. Still, this 2nd argument may be irrelevant if the point is just to keep you motivated rather than to track your weight.

<comment><USER11> Yes, but if you keep track of it, you learn how much weight a glass of water adds, for example, and you can calibrate for that. I'd say you learn more about how to control your weight in the long run if you keep track of these daily fluctuations.

<comment><USER10> But these fluctuations are often just noise. Having a glass of water before you step on the scale isn't going to help you lose or gain weight, but it still shows up on the scale. You're just micro-managing things that don't matter on this point. And then are just some things you can't control. If you have bowel movements at the same time every day, then that's not an issue; but if you go at different times every day (or not even every day), you might register as having gained two pounds one morning, when in fact you ate at a caloric deficit the day before.

But if you are going to weigh yourself every morning, keep this in mind and try to keep the exact same conditions every morning. Do it at the same time every day, either eat breakfast before weighing yourself every time or after every time, etc., otherwise you'll be worrying about changes in weight that don't mean anything.

<comment><USER12> The excel graph will take into account those little things. As long as the direction continues downward, the daily numbers don't matter.

</comment></comment></comment></comment><comment><USER13> When I was actively trying to lose weight, I was checking it every day. What I found was that I might lose a pound every day or so, then next day I'm up 3 pounds. But over time I was noticing a new, lower, upper limit to the down/up cycle.

At first it was 205, then 200, then 197, and now I'm surprised if I go over 180.

Yeah, checking it helped me keep u running and not eating crap, because it gave me some sense of accomplishment and further motivation.

</comment><comment><USER14> What gets measured gets done.

</comment><comment><USER11> This definitely works for me. I weigh myself each morning and night. I frequently weigh myself after drinking x glasses of water or eating a meal. Sometimes I'll even weigh myself hourly to learn how quickly I'm burning energy. After a few years, I've gotten a really good idea of what (and how much) I should be eating to lose or maintain my weight.

<comment><USER15> Weighing yourself hourly to see how quickly you're burning energy is misguiding. When you burn carbs/fat you're not expelling them from the body. You're converting them to another form in a process that releases energy that your body can use. E=mc^2 considerations aside, as you wouldn't be able to detect those differences anyway, your weight is still the same. The waste products later get expelled when you go to the bathroom, sweat, etc.

</comment></comment><comment><USER16> I'm traveling through the US South this week and the Publix grocery stores have scales in the entryways. (I assume for this purpose.) Great idea.</comment>


Ask HN: Motivational Curry to keep me up and going - <AUTHOR>

I am a regular HN reader. For the sake of my startup , I have moved to a city where I don't know anyone and live alone to minimize distractions, have an 8 hour day job in an startup environment and work hard on my product at night.<p>I am not in Boston/SV and do not have much resource to network.
Could you please suggest some good links which would help me in 1. network 2. teach more about startups 3. keep me motivated, focussed and fresh for more work. <comment><USER2> if there's no tech/startup meetup for your city, then start one. That's what we did in St. Louis -

<http://meetup.com/startlouis>

<http://meetup.com/codeuntildawn-stlouis>

<http://stljs.org>

Pick the topic you're most passionate about (or that would bring the types of people you want to meet) and make it happen. Pretty soon, they become friends. Pure motivational curry

Also - listen to the Lifestyle Business Podcast and This Week in Startups, and read the 4HWW at least once a year. My 2 cents

<comment><AUTHOR> Thanks! could you please point to the link of 4HWW and could you please upvote, so that it gets more eye balls.

<comment><USER2> [http://www.amazon.com/The-4-Hour-Workweek-Anywhere- Expanded/...](http://www.amazon.com/The-4-Hour-Workweek-Anywhere- Expanded/dp/0307465357)

<http://www.lifestylebusinesspodcast.com/>

<http://thisweekinstartups.com/>

hope this helps!</comment></comment></comment>


Diverging views on Big Data density, and some gimmes - <AUTHOR> http://databeta.wordpress.com/2009/05/14/bigdata-node-density/#more-140

<comment><USER2> He doesn't say Hadoop is 40x less efficient than PostgreSQL, he says Hadoop is 40x less efficient than eBay's Greenplum data-warehouse, which Wikipedia tells me is apparently a proprietary produced "based on" PostgreSQL.

</comment><comment><USER3> Headline is based on a totally muddleheaded interpretation of the recent sorting speed trial. Yahoo used 3800 machines to shoot for a sorting record -- not because they "need 40x the number of machines" as compared to a Greenplum PostgreSQL cluster for storing the data.</comment>


Decentral - John McAfee's Device to Thwart the NSA - <AUTHOR> http://www.mercurynews.com/bay-area-news/ci_24198989/john-mcafee-reveals-details-gadget-thwart-nsa?

<comment><USER2> The only thing that I know off that might be similar is the Freedombox.

[https://www.freedomboxfoundation.org/](https://www.freedomboxfoundation.org/)

</comment><comment><USER3> I would imagine any clever idea John McAfee thought of probably has a contingency plan in an NSA file somewhere.</comment>


Show HN: DevLab – Docker Containerization for Local Development - <AUTHOR> https://github.com/TechnologyAdvice/DevLab <comment><USER2> I stumbled upon Docker Compose yesterday, so please excuse my ignorance since I'm only familiar with it at a high level overview level, but Docker Compose looks very similar to DevLab.

How is DevLab different than Docker Compose?

[https://docs.docker.com/compose/](https://docs.docker.com/compose/)

<comment><USER3> Member of the DevLab team here :)

Compose is actually part of the reason we wrote this tool. We tried so hard to make it make sense for a TDD workflow, but it was always cumbersome.

Compose wants you to build your application into a container, and build and run that container every time you have a task to run. This takes time and a fair amount of cleanup, especially when you want a clean environment to run your tests that doesn't persist to the next run. DevLab just wants you to specify the environment to plug your application into, and doesn't build a container at all.

The result is:

\- No manual cleanup

\- No pile of images or processes that stack up

\- Your project doesn't have to be a Docker project. It doesn't need a Dockerfile. You can use this for something you plan to clone on an EC2 node and run from an upstart script.

\- No Vagrant/Ansible/Chef/Puppet, server config, anything. You pick out an image that matches your environment's needs (node:4.2, wordpress, go, etc., hub.docker.com is a great place to start) and DevLab plugs your app into it.

\- More development-oriented features outside of the pure Docker ecosystem that Compose stays confined to. For example, soon, Mac users running docker- machine will get to enjoy ports bound to localhost much like Linux docker users do [1].

To get this functionality outside of Compose, we had a monolithic makefile to maintain all of this for us. It wasn't DRY and it wasn't smooth. I hope you enjoy DevLab!

[1] [https://github.com/TechnologyAdvice/DevLab/pull/10](https://github.com/TechnologyAdvice/DevLab/pull/10)

<comment><USER4> > build and run that container every time you have a task to run

You don't have to rebuild each time, just use docker-compose rm -f and then run again. The old containers will be nuked, built docker images will be kept.

<comment><USER3> Fair point; I was speaking more toward the case of needing a rebuild any time your container gets changed, due to the change-on-run ethos of DevLab versus the change-on-build ethos of Compose.

But where cleanup really comes into play is when you have multiple tasks. You can specify multiple command paths in Compose, but each one will be a newly built image. With DevLab, you could `lab install` a node project, followed by a `lab lint`, or a `lab test`. You could `lab build` to compile your app at any time. And when you do this, whether it's the first time or the twenty- first time, overhead versus what you'd experience locally is just a second -- and the only image you have is your environment container. No build process, ever.

<comment><USER4> Sounds like you could get the same benefits by installing sshd into each container and using ssh to execute inside of a single container, rather than using docker/compose "commands". This would allow you to keep your `pip install` updates, and only when you run `docker-compose rm` would the changes be nuked. Would that fit the workflow you've been talking about? Thanks!

</comment></comment></comment></comment></comment><comment><USER5> Sorry I am pretty much a noob (specially at containerization) compared to most of the peeps here, but I can't resist asking - what is the need for this? What exactly does the author mean by "services (like databases) without needing to setup and maintain these environments manually"? Don't we just install node/mongo once ever followed by only updates?

My question is not just for this particular thing, but all "lets dev in a container" thing like python's virtual env, npm's "local hard copy of all the modules" etc.? Does it really happen that your node binary or $language interpreter/compiler gets infected/changed somehow? Or one of your crucial modules gets borked? And if it does, shouldn't we be looking at investigating _why_ such a thing really happened in the first place instead of duplicating everything?

As for maintenance, what kind of maintenance does node (or any $compiler or $interpreter) require? Don't they just sit waiting for invocation with some code to return the output/compiler binary? The only thing I have ever needed is stuff like nvm/rvm for using multiple versions of the same package/interpreter/compiler. Can anyone educate me?

<comment><USER6> As far as I can tell, the entire point is to ensure your code is platform independent from the start instead of making subtle assumptions derived from how your development boxes are configured. Making the test environment as similar to the deployment environment as you can.

<comment><USER5> Begging for an example ;)

I do understand this. And I do agree. But the more I think about it, the more I find that those arguments don't matter _in real life_. Code written in high level languages/platforms like node/ruby/python/etc. is _meant_ to be platform independent since the underlying VM abstracts the low-level details. Can you give me an example of the "configuration" differences that you (can?) encounter on different systems while developing on such platforms? (Except for the obvious and documented ones which containers can't solve either).

<comment><USER7> Here's an example:

A few weeks ago we had an issue where a db migration would not work on some of our developer machines (it worked fine on mine and in staging and in production). After a lot of sleuthing, we found that it was because their version of the database was slightly different because they had installed it months after I did. Furthermore, it was a real pain to roll back to the appropriate version.

A container that locked down the db version would have avoided all that.

<comment><USER8> We just have the particular versions of tools we rely on checked into perforce, and when there's an upgrade, you don't have to do anything different and everyone gets the upgrade.

</comment></comment></comment></comment></comment><comment><USER9> I think it just adds complexity by introducing yet another external dependency to dev environment. Not sure it will save time on projects with custom services (not available on Docker w/required configuration) vs running traditional VM.</comment>


World Ice Theory and the Supernatural Imaginary of the Third Reich (2017) - <AUTHOR> https://www.laphamsquarterly.org/roundtable/song-ice-and-fire <comment><USER2> Totalitarianism has to rely on lies. If people knew the truth and especially if everybody knew that everybody else also knows the truth they would surely revolt. The Emperor's New Clothes.

The main lie about totalitarianism is that some people are inherently entitled to rule over others.

The extra totally crazy lies are kind of a Canary in Coalmine, does anybody dare to confront them? If not then the big lie about the power of the totalitarian government is safe too.

</comment><comment><USER3> They present it as if it's ridiculous (and it is) but is it any more ridiculous than the mainstream creation myths that millions and millions of completely sane and rational people believe or claim to believe now?

<comment><USER4> just because they're in the majority doesn't mean they're sane, imo.

<comment><USER5> I'm fairly sure the majority of people don't believe in literalist young earth creationism. It's mostly a thing in certain Protestant sects, and regionally (especially in Turkey) in Islam.

If you're talking about the vaguer "evolution happens, but, er, maybe a deity did something non-specific about it", then that's more common, granted.

<comment><USER2> I never quite understood why many religious people have a problem with Evolution. If God created everything, surely he could create Evolution as well.

<comment><USER6> I think it's about the sense of personal meaning and importance one gets: if God personally crafted you down to the tips of your toes, that makes you feel more important and like your life is more meaningful than if God created some system (evolution) which just happened to eventually result in you at the current point in time.

<comment><USER2> Good point. At the same time it is pretty clear by observing how babies are born and grow up, and if you believe God created human race, that you do believe he "created some system" by which we grow from sperm and eggs, to be the way we are :-)

I think the way cells "evolve" to become mammals is actually much more wonderous than one species evolving into another.

</comment></comment></comment></comment></comment></comment><comment><USER7> Really totalitarians are all about believing their own flattering lies. Witness the "foes are strong and weak at the same time" hallmark and notice how incoherent and terrible their estimation of foes are. It is "good" at justifying travesties but incoherent doublethink doesn't lend well to strategy.

<comment><USER8> Plenty of non-totalitarian groups display these kinds of cognitive dissonances. This is not a unique, or even particularly noteworthy trait. It has little to no descriptive power.

</comment></comment><comment><USER9> Well, the reality is oddly close to the fantasy, actually. According to Wikipedia (Origin_of_water_on_Earth):

> The region of the protoplanetary disk closest to the Sun was very hot early > in the history of the Solar System, and it is not feasible that oceans of > water condensed with the Earth as it formed. Further from the young Sun > where temperatures were cooler, water could condense and form icy > planetesimals. The boundary of the region where ice could form in the early > Solar System is known as the frost line (or snow line), and is located in > the modern asteroid belt, between about 2.7 and 3.1 astronomical units (AU) > from the Sun.[18][19] It is therefore necessary that objects forming beyond > the frost line–such as comets, trans-Neptunian objects, and water-rich > meteoroids (protoplanets)–delivered water to Earth.

</comment><comment><USER10> I remember reading about how hitler supported missions to Tibet in search of a superweapon/power that will take the riech further

</comment><comment><USER11> there is a group of conspiracy theories around the idea the all those "scientific occultism" and "psychological warfare" ventures continued in the USA among programs such as MKULTRA and others (say the theories) not yet declassified because they were more successful.

I suppose you could categorize these close to "Hitler retired in Argentina" and similar "Nazism went on" conspiracies.

<comment><USER2> To quote a famous movie: The biggest stunt Devil ever played on us was he made us believe he doesn't exist.

"Nazism" is still going on. Nazism is basically the same thing as totalitarianism in general. It never went away in many parts of the world. There are even Neo-Nazis in the USA.

<comment><USER12> The Nazi party implemented a totalitarian form of government. Totalitarianism predated Nazis and is still a common form of government around the world. Classic case of "A is an example of B, but not all B are A". E.g. calling Stalin a Nazi would be inaccurate. He fought Nazis, but was still a totalitarian of the highest order, arguably with a more heinous legacy (if measured in body count, geographic impact, duration of influence). Assad is a current totalitarian, along with many regimes in Africa. Describing these as regimes as Nazis would be a very inarticulate description, even though I'd get your point ("he bad").

<comment><USER2> I think the differences between different totalitarian governments is of little significance.

What is important is that they all want to eradicate democratic processes as much as possible. So whether you call them "Fascists" (in Italy) or "Nazis" in Germany or "Stalinist" (in Soviet Union) is fine, but really they all are more or less the same, authoritarian, totalitarian, anti-democratic.

That is why Neo-Nazis call themselves Neo-Nazis. They want to be LIKE NAZIS.</comment></comment></comment></comment>


What do you think about ReactOS? - <AUTHOR> https://twitter.com/johnregehr/status/1146257172365373441 <comment><USER2> Discussion of original source: [https://news.ycombinator.com/item?id=20341022](https://news.ycombinator.com/item?id=20341022)</comment>


More Than 5.2M More U.S. Workers Filed for Unemployment - <AUTHOR> https://www.nytimes.com/2020/04/16/business/stock-market-today-coronavirus.html <comment><USER2> And those are just the people who filed for unemployment. Based on my experience of being a young person looking for work around the 2008 crash, I imagine there are millions of young people who want to work but won't find any, so they will simply move in with mom and dad. The total "unemployment" is almost certainly much higher than 14%.

<comment><USER3> To be fair that is the case pre-vivid, so there shouldn't be much of a difference for pure number crunchers.

</comment></comment><comment><USER4> 22MM total out of 157MM working Americans ~14%. More lost than have been added since 2008. Does anyone have a good idea about the actual prospects of a V shaped recovery?

<comment><USER5> So there are a few things to think about with respect to the recovery. Disclaimer: I am not an economist.

One thing is that to a certain extent an economy is psychological. Yes, certain things are physical realities (such as crop yields) or political realities (e.g. states of war) or legal realities (like regulations against selling homemade beer), but a lot else is purely based on sentiment. And it doesn't matter how good reality is if people think it's bad: they won't act in the market more than they must to survive, and it will actually _be_ a bad market, even if the fundamentals justify a good one — at least for awhile, until enough contrarians seek to take advantage of good prices (a kind of sentiment arbitrage, I suppose).

But something I worry about even more is well-intended interventions which make things worse and prolong the poor economy. There's precedent for this in history: the Smoot-Hawley Tariff Act was intended to alleviate the Great Depression but instead exacerbated it. Specifically, I can think of laws against so-called 'price-gouging' (which is a myth: no-one in all of human history has ever paid more for something than he felt it was worth to him at the time he bought it, because whenever anyone feels the all-in price for something is more than the all-in value … he doesn't buy it): by interfering with the price mechanism which is the fundamental method for economic actors to bid for their needs and desires to be met, it will result in less-efficient allocation of resources (capital and labour) across the entire market. This misinvestment will by definition lead to a poorer economy than would otherwise be the case.

<comment><USER6> _'price-gouging' [...] is a myth_

You're laying on the operating table in the ER with a heart attack. Surgeon says, _" OK before we put you under, in compensation I want 70% of your income for the rest of your life, or I'm not doing this. Deal?"_

</comment></comment></comment><comment><USER7> This is an unpopular opinion, but I think it's worth considering that most of these people are probably hourly wage earners, and so when things open up again, they will probably be hired back very quickly. The people aren't going anywhere, and they haven't been deleted from society. When businesses reopen this number will probably drop substantially. The businesses themselves (restaurants, retail, etc) haven't gone anywhere, they're just not operating. Yes there will be some bankruptcies, but those companies will restructure, assets will be sold, and something else will pop up in place.

If someone has a strong case for why this isn't true, I'd love to hear it, but it's my current working thesis and I haven't been convinced otherwise. I know it's unpopular because of politics and such, but I'm optimistic about recovery.

<comment><USER8> I am expecting to see record business at the local bars when the lockdowns end. The demand is still there.

<comment><USER9> Doubtful. There's not going to be a clear end time to this shut down, and I for one won't be going to a bar until I'm vaccinated.

<comment><USER10> There may never be a vaccine. If one can be developed, it may take years and it may not be completely safe and recommended for everyone.

<comment><USER11> There are 115 vaccines in development now, in four very broad categories. This is a well-understood process and will very, very likely lead to several viable vaccines.

Further, inoculation can occur much sooner. That is, introducing antibodies obtained from recovered folk, into vulnerable folk. This is nearing deployment right now.

Don't be a wet blanket. Its not all bleak.

<comment><USER12> We don't even know yet that people who have been previously infected have gained immunity. It's fine to be optimistic, but there are no guarantees here.

<comment><USER11> That seems like more wet blanket. How often does recovery not give immunity? Lets keep it real.

<comment><USER9> Recent studies point to 25-30% of people didn't have detectable levels of antibodies, or had too few for comfort.

Other coronaviruses, which are seasonal, have a reinfection rate of 30%.

More studies are needed, obviously, but dismissing real risks as "wet blankets" is extremely foolish.

<comment><USER11> That seems very strange. How did they 'recover' if they have no antibodies? Did the virus give up on its own?

A reinfection rate of 30% seems bad. How does that translate to an R0 I wonder.

<comment><USER9> It's not at all odd, Antibodies aren't forever. Chances are you've been reinfected with something you built up antibodies for dozens of times in your life.

For reasons currently unknown to science, exposure to some diseases confers lifelong immunity (chickenpox) but does not for other diseases (Flu, coronavirus, various types of common cold).

We're actually starting to see the first reinfections of COVID-19 patients.

</comment></comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER13> [https://archive.md/QpWki](https://archive.md/QpWki)

</comment><comment><USER14> I understand from the perspective of competence why the US wasn't able to freeze mortgages/rents and absorb payrolls as other countries have, but it really seems like they missed their shot to save Capitalism.

Millions upon millions of unemployed people, many watching their friends and family die from disease, a psychotic, entrenched politics, that caters primarily to corrupt elites...

Historically, things don't go very well from here.

<comment><USER15> Save capitalism? I think that is a great over reaction, the Great Depression, crash of 87, nor of 2008 stopped it. So I am quite certain this will be but a hiccup when we look back 10 years from now.

<comment><USER10> The Great Depression resulted in the welfare state. It forever changed the balance between state and private sectors. It certainly was not a hiccup.

</comment></comment></comment><comment><USER16> I received a message from our overlords that staying at home is staying safe.

I don't feel safe.</comment>


Why I Left Point72 for Crypto Investing - <AUTHOR> http://fortune.com/2018/08/01/crypto-hedge-fund-why-i-left/ <comment><USER2> Nobody invests, everybody speculates. Even bank accounts carry risk in certain circumstances.</comment>


The FBI searched a protester's Etsy profile, LinkedIn, and internet history - <AUTHOR> https://www.inquirer.com/news/philly-protests-arrests-fbi-lore-elisabeth-blumenthal-george-floyd-20200617.html <comment><AUTHOR> Note: the full title of the article is: _The FBI used a Philly protester's Etsy profile, LinkedIn, and other internet history to charge her with setting police cars ablaze_ , which is 50 characters too long for HN's title limit.

I did not omit the "to charge her with setting police cars ablaze" as a way to mislead people into thinking the FBI were doing a dragnet of Internet histories of all protesters. The meat of the article is the (mostly logical and common-sense) investigative techniques the FBI used to uncover the protester's identity. What she's charged with, or whether she's guilty of it is tangential – though obviously the seriousness of the crime they accuse her of is a likely factor in how much work they put into searching for her.

To put it another way, it's interesting (and a relief) to me that they didn't find her out using a mass geofencing request, or other big data request that _do_ constitute large scale dragnets.</comment>


Progress and its Sustainability - <AUTHOR> http://www-formal.stanford.edu/jmc/progress/

<comment><USER2> [http://www-formal.stanford.edu/jmc/progress/notes.html#tract...](http://www- formal.stanford.edu/jmc/progress/notes.html#tractor) cites an advertisement from 1921:

``Keep The Boy In School

The pressure of urgent spring work is often the cause of keeping the boy out of school for several months. It may seem necessary - but it isn't fair to the boy! You are placing a life handicap in his path if you deprive him of education. In this age, education is becoming more and more essential for success and prestige in all walks of life, including farming.

Should you feel that your own education was neg- lected, through no fault of yours, then you naturally will want your children to enjoy the benefits of a real education - to have some things you may have missed.

With the help of a Case Kerosene Tractor it is possible for one man to do more work in a given time, than a good man and an industrious boy, together, working with horses. By investing in a Case Tractor and Oxxx Detour Plow and Harrow outfit now, your boy can get his schooling without interruption, and the Spring work will not suffer by his absence.

Keep the boy in school - and let a Case Kerosene Tractor take his place in the field. You'll never regret either investment.''</comment>