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Astronomy Stack Exchange

Questions tagged [universe]

Questions regarding all of time and space and its contents.

The Universe is all the contents of space and time — in essence, it is everything that exists, has existed, and will exist, everywhere.

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Are there more stars in the universe than grains of sand in the Earth?

My ten year old daughter asked me this question at breakfast and I initially said yes, but on second thought I was also puzzled.
Ruy
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Is there any practical use for astronomy?

Although astronomy is very cool and the things we are learning are awesome, is there really any practical use to knowing the things we know about the universe? Do other fields of science draw from the current tome of astronomical knowledge?
Scottie
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Will there be collision between universes?

I just watched one of those videos that shows the scale of the universe, zooming out from one thing all the way out to the sphere that is thought to be the universe. However, they also showed other universes outside our own, and they made it seem…
Margorp13
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If the universe has no true center, could it have antipodes?

Some time ago, I wondered where the center of the universe could be, and the answers I found were pretty much in agreement that there was no center of the universe, as paradoxical as that might seem. So I started wondering, just as the surface of…
J-L
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Layout of the universe

I've been working on a space game in my spare time, and lately I've been thinking on how to lay out the universe. Though I've searched around and found it hard to get a good view of what the universe looks like. I did find a lot of good sources,…
The Oddler
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Do parallel universes exist?

Do other universes like ours exist? If they exist, how do we know that they exist when we have even not seen the ends of our own universe?
ashu
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How exactly is our universe mapped?

Watching this youtube video shows that our planet is nothing more than dust in the wind. At the 2:50 mark in the video, you will see a view of the whole Milky Way. At the bottom you will see this text Light travel time from earth: 100,000…
PrivateUser
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What's the largest non-spherical astronomical object in the universe?

Some asteroids and comets are non-spherical. But is the nature of big things and gravity so that large things in the universe are always spherical? What is the biggest astronomical object in terms of volume out there that's not spherical? Note:…
bogen
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is there any theory or observational evidence that our universe is electrically neutral or not?

It seems our universe is neutral in large scale. There is CP violation (wiki) problem with respect to matter and antimatter. Similarly is there any theory about whether our universe is electrically neutral? Cosmic rays are not neutral. However the…
questionhang
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Why does it make sense to say the universe has no centre?

If we suppose we and everything in the universe is perfectly flat. That is, we have width and depth, but no height. And we are situated on the surface of a balloon blowing up with air and expanding "outwards". Us flat people can move around on…
Michael Lee
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Are there only $10^{83}$ atoms in the universe?

I'm a high school junior. I assumed there would be an incredibly huge number of atoms in the universe if not infinite. Recently, I've come across a few articles which claim that scientists believe there are 1083 atoms in the universe. I'm not sure…
Alexa
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What is the physical, geometric shape of the universe?

I'm not asking about theoretical ball, vs saddle, vs flat surface which is just a metaphor with 2D space. It's hard to say as we see very little of it, and we see them in the past because light travels for so long. But what we do know is that it is…
Ska
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Does our universe have to be embedded in a higher dimensional space?

I've heard that our universe may be open or closed. If it's closed it might have a toroid shape. If this is the case, would that imply that our 3 spatial dimensions have to be embedded in a higher dimensional (spatially) space? For example, the…
Mitchell Kaplan
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Does the universe have an edge?

I've heard the universe is just an empty cavity. Does the universe have any edge or stop or is it just an infinite empty cavity?
user73898
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Who first hypothesized that the universe is accelerating?

I couldn't find this answer anywhere. Before 1998, was there a notable physicist who conjectured that the universe is accelerating and perhaps even submitted some equations to support it (and the existence of dark energy). Such a hypothesis would…
prestokeys
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