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On the first episode of _Sword Art Online_ we know about a microwaves device
installed on the helmet. We learn that this device can damage to death the
user's brain removing the limiter. Unplugging the device causes the battery to
activate as fallback, using the remaining power on the battery to damage the
brain of the user.

The main device of a today microwave oven is
[magnetron](http://en.wikipedia.org/wiki/Cavity_magnetron), I cannot find any
example of a magnetron consuming less than 1kWh as now (I accept correction),
emitting more than 600W in microwaves. As of current technology, can a
portable battery provide enough power to burn a brain? Are there more details
about this issue described later in the anime or in the novels?


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2013-05-28T13:12:59.220
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2014-09-03T10:41:36.503
2014-02-02T23:56:11.177
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sword-art-online
How does the NerveGear fallback battery work?


Lets say the magnetron indeed has a power requirement of 1kW (I never tried,
so I might be off with this value and 1kW is not enough to burn a brain. On
the other hand, I guess it also depends on the duration the magnetron is
turned on.)

Lets also say a mobile(-ish) battery of 50V is used (I do have to pick some
value, right).

[P = V * I ](http://en.wikipedia.org/wiki/Electric_power), so it would draw
1000W / 50V = 20A.

Now, lets say a brain is fried in 1 minute (maybe this assumption is too high:
if it takes too long the 'immediate dying' effect would be gone? Although some
agony is a pro in the eyes of an evil mastermind)

So [this
battery](http://em3ev.com/store/index.php?route=product/product&product_id=106)
for example (disclaimer: first one I found; I do not own stock for this
company) seems to be sufficient. As it should be able to power it for about 1
hour (19.5Ah)... It is a bit heavy with its 8.8kg, but we do probably not need
power for one hours, so a smaller battery should be sufficient, weighing a lot
less.

* * *

So in short the answer is (with these crude estimates and calculations): Yes
it is possible to power a (mobile-ish, the magnetron you linked to did not
look too mobile as well) device with our current technology.

I did not read the manga or anime, but I guess the complete system needs to be
scaled down to match the description and fit in a helmet...


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2013-05-29T14:52:32.937
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2013-05-29T14:58:01.663
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In light novels there is no "infinite batteries". Kayaba says "You will die if
you're unplugged from the electricity or the internet for more than 10
minutes". Infinite battery thing is made by anime productors.


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2014-09-03T08:05:32.033
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