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But it's not just starlight - it's the light of a whole nova (and the collective light of a whole galaxy.)

I can see starlight from the bottom of a pool, but the water in the pool will still stop a bullet.

(I am not a scientist, I could be entirely wrong, but it seems like the collective dust of 12 million light years would surely ground down a bullet, while being intermittent enough to let starlight pass through in aggregate.)




Well let's calculate it. According to http://www.universetoday.com/30280/intergalactic-space/ there is about 1 hydrogen atom per cubic meter. According to https://www.google.com/search?q=light+year+in+meters&ie=utf-... there are about 10^16 meters in a light year. So 12 million light years is about 10^23 meters. Avagadro's number is about 6 * 10^23. So a tube a square meter across is a bit under 0.2 moles of hydrogen. According to http://answers.yahoo.com/question/index?qid=20080619205711AA... at standard air pressure a mole of hydrogen would be about 22 liters, so we're talking about 4 liters of gas at standard pressure. Which would be about 1 square meter across, and 4 millimeters tall.

The collective dust of 12 million light years of intergalactic space does not seem likely to grind down a bullet very much.

That said, the whole calculation is flawed because first you have to get out of our galaxy, which is much higher density. Though that also wouldn't stop a bullet. But then you have our atmosphere, and that most definitely would destroy a bullet that tried to pass through it!

But the moral remains. Space is empty. Really empty. Unimaginably so.




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