71–80 of 310 posts
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Number of stars in the Milky Way: 100 billion Number of galaxies in the universe: 200 billion to 2,000 billion
Is 2,000 billion some theoretical limit or something else? Thanks.
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There really is a lot of stuff left to see for the first time
"A lot" is the number of fish in a swarm maybe. This is so far away from our concept of counting things that the mind just gives up. There's no comparison, no dumbing down to X amount of football fields, just nothing. I find it depressing, confusing but also inspiring and fascinating at the same time.
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This is only true if we believe Earth is special, which we have no bases. So I'll stick to statistics for now, thank you very much.
Why does that make the earth special? Is the single one in a million dimensional one-hot vector special? Why? If only intelligent life can have this conversation then it will always be "but why us?!?!" well, it was random. Just the other random values don't get to ask the question...
"It was random" in my opinion explains little. If it was sentient, maybe the dice would say "why did I land showing my '6' face? Why me?" and the answer would be many other dice landed showing their '6' faces. Random, but given enough dice rolling you'll get another '6'.
The universe is finite but it's mind-boggingly large. I think Earth is special because a- I was born there, enough said, and b- it has just the right conditions and luck for life to exist. But I don't think it's so special that it's the only planet in the whole mind-boggingly large universe to be this way. There must be other planets/dice rolling out there.
Until we find another such planet we cannot know for certain, but in my opinion it seems unlikely that these conditions don't exist anywhere else but on Earth. Why? Well, because the universe is so large -- the dice pool is very, very large.
Gorgeous and upsetting that I'll never be able to visit it. 13 billion years before me, potentially trillions of years after me. Seems like such a waste of the spark of awareness that I can't take that awareness and experience the galaxy in all its glory.
Isn't a nebula a cloud of dust? I'm not sure how dense it gets, but would someone even notice if they were inside of the nebula?
I think "dust" is a term of art in astronomy. A cloud of rocks the size of cars could be dust. I suppose that if you can't resolve the particles, then it's dust.
If I look at this part of the Orion Nebula, it looks opaque; I can't see what's behind it. So I guess if I were in the middle of the nebula, then I wouldn't be able to see out of it. There are many stars in the nebula that are not visible (in visible light).
So I suppose that what you'd see would depend on where in the nebula you were sitting; if you were near a star, the dust would be illuminated, and the sky would be bright. If you were not near a star, presumably the sky would be dark, and you'd look up and see nothing, like the inhabitants of the planet Cricket.
The youtube link to a 'zoom' in video to the image: https://www.youtube.com/watch?v=TkVprNB5XbI What is really, really neat to notice isn't just the detail in that final image.... look behind it, and there are whole edge-on spiral galaxies in the distance. Not stars. Galaxies. The nebula is about 1375 light years away. Those galaxies in the distance.... are billions of light years away. It's hard to comprehend.
The zoomable version: https://esawebb.org/images/weic2411a/zoomable/
Wow. The NIRCam image is probably going to be the most exciting new photo, but I can't get over how well MIRI reveals the internal structure of the nebula. NIRCam: https://www.esa.int/ESA_Multimedia/Images/2024/04/Horsehead_... MIRI: https://www.esa.int/ESA_Multimedia/Images/2024/04/Horsehead_... Comparison: https://www.esa.int/ESA_Multimedia/Images/2024/04/Slider_Too...
And when 'zooming in' and seeing the top 2/3 of the photo ( https://www.esa.int/var/esa/storage/images/esa_multimedia/im... ) I am super amazed that all these small discs showing are galaxies. GALAXIES (sorry for the caps). How tiny are we (Humans, Earth, Solar system)... less than a speck of dust in the Sahara. I used to look up in space when I was growing up and there wasn't any light pollution to the small town I…
What's more amazing is when you share this fact to most people "did you know each dot here is a GALAXY, not a star!" they go "heh... interesting" and shrug.
For some reason that makes the whole thing even crazier to me
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Is 2,000 billion some theoretical limit or something else? Thanks.
Yes. Take the age of the universe, multiple by the rate of expansion to get the total size of the universe, then multiple by the average density of galaxies in the observable universe. There are some further complications, but at the root it is basic algebra.