Questions tagged [universe]

Questions regarding all of time and space and its contents.

Filter by
Sorted by
Tagged with
3
votes
1answer
654 views

Latest cosmological parameters

I'm looking for the latest values (with uncertainties) of the four main cosmological density parameters $\Omega_i$ : \begin{align}\tag{1} \Omega_{\text{mat}} &={} ?, &\Omega_{\text{rad}} &=...
3
votes
3answers
192 views

Does the universe curve in on itself?

I've read a little bit about the universe, but its not clear to me if there is a place in the universe beyond which there are no stars. For example, is there anywhere in the universe that one could ...
3
votes
3answers
653 views

How can the universe be expanding faster than speed of light? [duplicate]

So the story goes like this: A long time ago, 13.799±0.021 billion years to be exact, something happened. It was a big bang, loud explosion and universe came to existence. It grew and grew, and now ...
3
votes
1answer
294 views

Would a future hole in the Cosmic Microwave Background show us the edge of the universe?

If my understanding is correct, the Cosmic Microwave Background always come from our event horizon. By event horizon I mean the edge of the observable universe. If the universe is finite does it mean ...
3
votes
3answers
332 views

What's the name of outside the cosmic horizon?

The word we use to refer to what's inside the cosmic horizon is the 'universe', so what would you call the empty space outside of the horizon?
3
votes
2answers
749 views

Why are distant galaxies not visible in the observable Universe?

Assuming that the Universe is and has been expanding ever since its creation (Big Bang theory), the galaxies that are now at the 'edge' (not visible theoretically) must have been (at some point in ...
3
votes
1answer
87 views

Based on the smallest number of photons that can deliver information about a star, what is the largest size of the universe?

I was watching a summary video about the Banach-Tarski paradox and it led me to a question. If I (a) assume the universe is infinite and (b) assume it is possible to receive a single photon of light ...
3
votes
1answer
635 views

In the end what is the ultimate matter/element in the universe, due to fusion process in stars?

We know that, in stars, hydrogen is used by the stars and due to the fusion in two hydrogen elements we get helium -> Carbon -> Oxygen ->Other elements -> Iron -> then Super/Hypernova. If everywhere ...
3
votes
3answers
148 views

Is the eventual heat death of the universe due to the expansion of the universe?

I am reading about the accelerating expansion of the universe and something struck me. The observation that things further away were accelerating away faster and that early observations made it look ...
3
votes
2answers
116 views

Light beam (1 photon) in the limited universe?

If our universe is not infinite, what happens with the light beam (or photon) when it will travel through the whole universe? For example, observable universe according to wikipedia has diameter 93 ...
3
votes
1answer
697 views

What will the universe be like in a googolplex years time?

It will be cold and dark in 10^(10^100) years. What else can be said of the state of things in the far distant future? Will everything have fallen into supermassive black holes and then radiated ...
3
votes
1answer
3k views

Why is there a difference between the cosmic event horizon and the age of the universe?

According to wiki the cosmic event horizon is 5 Gpc but the age of the universe is about 13,7 billion years. Usually light from far galaxys needed at most 13,7 billion years to reach the earth so the ...
3
votes
1answer
233 views

What was “space” like before big bang?

I have a simple question which I think about often but have no answer. If The Big Bang is true, than if the whole space was just a point 14 billion years ago, then what was around that point, some ...
3
votes
2answers
199 views

Is mass+energy conserved when a new universe forms inside a black hole?

My understanding is that there are credible theories out there in which the formation of a singularity in a black hole also represents the beginning of a new universe via a big bang. We can't see the ...
3
votes
1answer
152 views

visualisation of the universe's expansion

in physics we were learning about the universe and the big bang. we were being told that everything came from one point and 'exploded' outwards, and is continuing to expand. I felt that this ...
3
votes
3answers
525 views

How is the universe bordered?

This answer says that some models describes the universe as finite. How do those models describe the universe's border? Does the border (theoretically) exist? Is it a solid border? Do they predict ...
3
votes
1answer
116 views

Does a flat universe mean not finite and circular?

I am trying to wrap my head around what a flat universe means; Trying to imagine why angles of triangles in spherical volumes are different. Because my brain can't do that well and I became a bit ...
3
votes
2answers
111 views

Does the expansion of the universe increase with distance?

I read something in a book the other day which has gotten me really confused. They were talking about the expansion of the universe, and if I understood it all, they said that the expansion of the ...
3
votes
1answer
411 views

What suggests the cyclic nature of the universe? Proposed by Stephen Hawking

In "A Briefer History of Time" by Stephen Hawking he writes that if we were to travel faster than the universe were expanding and for long enough (in a straight line) we would eventually come back to ...
3
votes
2answers
133 views

Are there any sounds in space?

Is our universe noisy or silent? Can people hear them? When astronauts are out of the Earth and near an explosion, can they hear its noise.
3
votes
2answers
538 views

Is it possible to create an artificial Black Hole?

I am quite curious about black holes. Once I just thought whether it is possible to create an artificial Black Hole, i.e. an human made black hole. Also explain there formation if it is possible.
3
votes
2answers
150 views

Is there any proof of space being created?

Is there any proof for space being created? Because I guess an explanation for the dark energy (dark = our understanding of it) could be that there is a gigantic amount of matter/dark matter that we ...
3
votes
1answer
203 views

How could we tell if the Universe is infinite? [duplicate]

I've heard from a number of people that the Universe is infinite, and from my perspective, I can't see how this can actually be known, especially given that the Universe started out a finite size and ...
3
votes
2answers
147 views

The universe is dying vs the universe is ever expanding

How does the idea that the universe is dying (trumpeted as some big new revelation the past few days on several new sites I keep seeing pop up on google news) square with the idea that the universe is ...
3
votes
3answers
2k views

What does Stephen Hawking mean by 'an infinite universe'?

In the recent $100m search for extra terrestrial life project project, Stephen Hawking is quoted in the following way: "We believe that life arose spontaneously on Earth," Hawking said at Monday's ...
3
votes
3answers
116 views

Account for radiation energy in the statement “total energy of universe is zero”

I've read in Hawking's book The Theory of Everything that total energy of the Universe is zero. He explained this by saying that if there are two bodies separated by a distance and having some mass, ...
3
votes
1answer
134 views

Universe becoming finite

If sometime in the distant future, the Universe stopped expanding, would this mean that the Universe was no longer infinite?
3
votes
2answers
463 views

Is time itself speeding up universally?

Time moves more slowly near a mass than in relatively empty space. For example, I get that an observer would see someone falling into a black hole to appear to move more slowly and get "stuck" on the ...
3
votes
3answers
211 views

Why can't this be the simple (and obvious) explanation for the dimming of KIC 8462852?

Couldn't it be just a relatively large object, anywhere in the interstellar space between the star and Earth? I mean, look out the window at a far away car or a tree, then stretch out your hand and ...
3
votes
1answer
117 views

Methodology for size of Universe

I understand that the Universe could be either finite or infinite and that it is, at the least, "very large". :) My question is, why doesn't the math involved in making the CMB and other predictions, ...
3
votes
2answers
65 views

How to fix a Direction in the context of universe? [duplicate]

My question is regarding the direction/orientation of earth. Is it a constant with reference to universal parameters?
3
votes
1answer
542 views

Total mass of light? [duplicate]

I know that light is considered as energy, and as such has a mass. So it is certainly taken into account in universes models and calculations. So I'm wondering: How much of the total mass of the ...
3
votes
3answers
402 views

How does dark energy remain constant?

According to cosmological constant, dark energy should have a constant density but since the universe is expanding so is the volume of the universe and so should the mass of dark energy. But how does ...
3
votes
1answer
850 views

Big Bang / Big Crunch cycle?

I've been reading some of Stephen Hawking's work on the theory of the expansion (and ultimate contraction) of the universe and was curious if anyone has every hypothesized that the universe has ...
3
votes
1answer
254 views

Does the holographic principle contradict eternal inflation?

As it is for example explained here, Andrei Linde's chaotic inflation is among the potential winners or survivors of the spring cleaning induced by the potential detection of primoridal gravitational ...
3
votes
2answers
225 views

How can cosmological bubble universes “collide” with each other?

In Eternal Inflation Theory, there exists the idea of multiple "bubble" Universes that grow and according to this theory, can "collide" with each other. The paper suggests that you can search for ...
3
votes
1answer
82 views

Formation of our Universe

So I got this information from a magazine , Scientific American issue Physics at the Limits. The theory is that our Universe came about, when in the "Bulk Universe", which is four dimensional, a four ...
3
votes
0answers
99 views

Is the acceleration of the expansion of the universe a direct observation or an interpretation?

Is the acceleration of expansion we observe with supernovae direct or is this an interpretation according $\Lambda$CDM model ? I mean what we observe is luminosity distance versus redshift, so to see ...
3
votes
1answer
947 views

“How the Universe Works”: is it scientifically accurate? [closed]

The documentary/mini-series How the Universe Works is based on scientific evidence and according to what is known nowadays, or sheer bunk? Throughout the series, are there any particular topics which ...
3
votes
0answers
72 views

What is that void that the universe is growing into? [duplicate]

We understand that this is the universe and it is essentially full of space and time, but what is on the outside of the universe, and isn't that nothing, something, and how far does that reach. I.e. ...
3
votes
0answers
86 views

Can we only see the past of the universe? [duplicate]

So I was reading some interesting stuff about universe and Big Bang and wanted to make sure one thing. As far as I understand everything we can see about universe is the past, right? I mean all the ...
3
votes
1answer
148 views

Could the Universe really be 12.5-13 billion years old?

My initial reaction is that "this must be wrong" and apparently that's a lot of people's initial reaction according to the article. https://www.nbcnews.com/mach/science/universe-may-be-billion-years-...
2
votes
2answers
121 views

How much of the Universe is subatomic? [closed]

How much does subatomic particles such as photons, tachyons, and electron being the biggest particles etc. occupy space? If put in a ball how big of a ball would that be?
2
votes
3answers
408 views

Is our universe flat?

I heard our universe is flat. Then one question is puzzling in my mind. If our universe is really flat, why we measure distance from any point across in a spherical way. In other words, why we say, ...
2
votes
4answers
357 views

Can there be an infinity of humans in the Universe? [closed]

I was reading this question about if the number of stars can or cannot be infinite. The answer to this question is: ...
2
votes
2answers
258 views

What explains the existence of energy/matter if it cannot be created or destroyed?

If the energy/matter that was contained in the singularity before the Big Bang had always existed, and if it’s true that energy/matter cannot be created or destroyed, then what explains its existence?
2
votes
2answers
4k views

How can I see a nebula?

I've recently been seeing a bunch of pictures of nebulae and I'm just fascinated by their beauty and complexity. Is there any kind of telescope that would make it possible to view it from here on ...
2
votes
2answers
426 views

Can the theory of multiverse explain dark matter?

If there are many universes, they must have a gravity effect on each other. Since dark matter is measured through gravity, but we don't know the mass behind it, isn't it possible that it comes from ...
2
votes
1answer
478 views

If the universe is 'flat', what shape is it? [duplicate]

As in the title, If the universe is considered to be 'flat', what shape is it? Is it a disc, elliptical, square, rectangle? Or is this still unknown as we can only study a small segment of the ...
2
votes
3answers
211 views

If the expansion of the universe is speeding up, how long until everything nears the speed of light, and what would happen?

Since dark energy is causing everything to speed up infinitely, wouldn't everything near the speed of light? And since it's nearing the speed of light, wouldn't all kinds of strange things start ...