*First, the inspiration for this question:*

I just read that it takes one hour to send a picture from the New Horizons space probe, to Earth. It also takes around 5 hours for that picture to reach earth.

This means that there are about 4 pictures "floating" in space, somewhere between Pluto and earth. 

This information is energy, and energy contributes to gravitation somewhere between Pluto and Earth at this moment.

**Is this last assertion correct?**

If so:

The sun outputs $10^{26} \text{ watt}$ of energy. It's been doing that for more than 4 billion years. In the observable universe, there are between $10^{22}$ and $10^{24}$ stars.

If the average star is similar to the sun, and we ignore energy that has been stored in planets, then up to $10^{(26 + 24)} = 10^{50} \text{ watt}$ of energy is being added to "empty space".

4 billion years is something like $10^{17}$ seconds (rounded down).

This means that there might be as much as $10^{(50+17)} = 10^{67} \text{ J}$ of energy, just moving about the universe.

**Is this negligible?**

The amount of energy is probably much higher than $10^{67}\rm\,J$, as I do not take into account light that was emitted more than 4 billion years ago. It also does not take into account stars beyond our observable universe.

I apologize for using very simplified estimates, but since the numbers are so big the errors become less important. I have naively used $E=mc^2$ to go from joules to kilograms. I get something like $10^9$ Milky Way masses.

Is this energy taken into account, when scientists say that the universe is expanding? I have a feeling that this energy would make it *appear as if the universe is expanding faster*.