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Comment by dfee | Hacker News Reader

Two amazing things:

1. these photos have been traveling for 13.5 billion years, just to meet their fate smashing into the JWST.

2. how many photons must have been emitted, that a sphere 13.5 billion light years in radius can still resolve the image.

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Well, due to the massive gravitational lensing from the intermediate galaxy a few billion years away, I guess it's not actually a perfect 13½ billion light year sphere right... It's a fair chunk of the photons in the 10 billion light year sphere swept up and focused over a vast area and pointed in our direction.

Still amazing to think about though.

I get the same amazement when I think about an ant I see on a tree five feet away. A photon was born somewhere in the middle of the Sun thousands (or more) years ago. It eventually made its way to the surface and—at extreme improbability—it traveled directly toward Earth. With more extreme improbability, it found itself on an intercept course with a tiny little ant on a tree.

Layer on yet another high improbability, that photon-ant collision just so happened to send it directly toward me. Wait, not just me, but the tiny little pupil in one of my eyes!

Tremendously large numbers and crazy minuscule fractions can be found in your backyard. Don't even need to leave the Solar System.

The radius of the universe is closer to 46 billion light-years:

https://en.wikipedia.org/wiki/Observable_universe

The photons have emanated in a sphere from point of origin with a radius of 13.5 billion light years.

The radius of the universe is irrelevant.

Well, it's a good point no? If the universe is expanding as the photons propagate they are spread out into that larger sphere. So for the purposes of light gathering, a galaxy 13 billion years in the past has its photons spread over that much larger sphere into even greater invisibility. Although I guess in this case they were spread out into the larger sphere at the point of the expansion of the universe of a few billion years ago before being focused towards us - so. Some value significantly smaller than 46 but a lot larger than 10. Which makes it even more amazing to think about.

Do you have an evidence that space and time can be stretched at all? Can you stretch it a bit for me?

I just ate a bunch of food. I am now more massive. So I have stretched space around me a bit more than I did before I ate. You just need to make an instrument sensitive enough to detect it.

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