Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [universe]

Questions regarding all of time and space and its contents.

-5
votes
2answers
71 views

The Expansion Of The Universe [on hold]

I am informed that a volume of nothingness can expand many times over for no good reason,becoming filled as it does so by colossal numbers of virtual particles which appear ultra-briefly out of ...
2
votes
0answers
39 views

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

I'm reading this paper which suggests that you can search for evidence that our Universe collided with other "bubble" Universes, by looking for an imprint on the CMB radiation. However, the concept of ...
3
votes
2answers
77 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 ...
0
votes
1answer
74 views

Invisible Mass Affecting the Expansion of the Universe

Are there enough neutrinos & other invisible particles in a cubic light year of space to significantly affect the expansion of the universe,& at a very rough estimate without taking into ...
0
votes
0answers
19 views

How is “surface brightness dimming” derived from redshift in the NED extragalactic database

I have several questions regarding “Surface Brightness Dimming” in the “Quantities Derived from Redshift” section of the Nasa/ipac Extragalactic Database. As an example, please use quasar IRAS F08279+...
0
votes
1answer
59 views

how to define the universe itself is expanding greater than than the speed of light?

since we observe galaxies and other steller objects in very tiny tiny scale, and how we can understand that the speed of expansion on universe is higher than the speed of light ? even using the ...
-1
votes
2answers
239 views

What covers the outside of the Universe? [closed]

Is the Universe a sphere with water or ice surrounding its' confinement? Are there any theories that imply the Universe being confined within a sphere of water/ice material?
1
vote
2answers
183 views

Are there ways to estimate size of the “whole universe”?

Words escape me, but by "whole universe" (I think) I mean everything that's spatially connected to the observable universe in a conventional sense. If there is a better term for it, please let me know!...
0
votes
1answer
54 views

Have we measured or found evidence of a detectable origin point of the big bang? [duplicate]

Based on reading the wiki page of the big bang, a simple question with a probably not a simple answer came to mind. The statement on the wikipedia page was. Since Georges Lemaître first noted in ...
2
votes
0answers
36 views

Universe as 3D projective space? [closed]

Is there any benefit to view the 3D (real) universe as 3D projective space?
1
vote
2answers
93 views

If objects don't move when the universe expands, how can the expansion result in redshift?

I am approaching this topic from a layman's perspective and view this as a logic puzzle, but when someone tries to get me to accept the logic, I'm never convinced by their arguments. According to ...
1
vote
1answer
85 views

Did universe have finite hydrogen

According to this video stars at end of time and many others on fate of universe they all agree on one thing that stars will eventually convert all the hydrogen into heavier elements and eventually ...
3
votes
0answers
107 views

As the Universe expands, do things like planets expand also, or just the space in between?

Just what the question says. As the universe expands, and space expands, do objects like planets ever expand? Does the space INSIDE of those objects expand?
1
vote
1answer
85 views

Looking at the Expanding Universe through the lens of relativity [closed]

The basis and most observable metric for how the universe is understood to be expanding at an accelerating rate is the red shift in observable light. I am assuming it has been thought about or maybe ...
4
votes
1answer
108 views

How can you verify the theories presented on TV shows like “How the Universe Works” is current and/or valid? [closed]

There are many TV shows such as "How the Universe Works" that explain theories about the origin of the universe such as the Big-Bang Theory. What resources can I access to verify the scientific ...
5
votes
3answers
431 views

Can two planets in an empty universe meet/be pulled together?

For this question assume that the entire universe is completely empty. The universe is not expanding or contracting, it is completely motionless since time immemorial and has never moved before. Only ...
1
vote
1answer
96 views

What was the process of calculating how much darkmatter/matter/dark energy the observable universe consists of and how did it come at this conclusion

In 2015 the Planck satellite consortium released an analysis of data collected by the Planck satellite that showed this percentage break down of the universe’s mass/energy. Ordinary matter: 4.9% ...
5
votes
1answer
322 views

Is our universe stable or metastable?

I've been reading and thinking about this subject for some time, but I can't seem to find a clear answer. After reading Q14: Aspects of the Higgs boson suggest that our Universe is only “...
1
vote
1answer
66 views

Is the universe always expanding

Currently we observe that the universe is expanding. And this expansion even goes faster and faster. Why do we know (or presume) that this expansion started slowly at a singularity (i.e. big bang) ...
2
votes
0answers
62 views

What is the total number of stars in the universe? [duplicate]

I mean a total number of stars, not the only ones that we can see.
2
votes
2answers
117 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?
0
votes
1answer
70 views

Why Is The Expansion of The Universe Allowed To Move Faster Than Light? [duplicate]

Why is the expansion of the universe allowed to faster than light if everything that moves within a vacuum can't reach the speed limit of light? I've read that astronomers looked at the distance ...
1
vote
0answers
64 views

3-sphere universe [closed]

I have just read on this site that there is a Newtonian solution to Einstein's field equation but that it is spherically symmetrical and therefore not isotropic (having a centre for example) and so ...
0
votes
1answer
67 views

How can the universe be expanding? [duplicate]

I assume expansion implies an increase in the volume of the universe. But if the volume of the universe is increasing, does that not imply the area it is expanding into's volume is being reduced?
2
votes
2answers
128 views

What happens for a “closed” universe without any content?

Let an universe with no content and positive curvature. Friedmann-Lemaître equation $$H^2=\frac{8\pi G}{3}\left(\rho_m+\rho_r+\rho_{\Lambda}\right)-\frac{k\, c^2}{a^2},$$ where $a$ corresponds to the ...
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 ...
1
vote
1answer
120 views

Is it possible that the Universe is expanding due to additional Big Bang events?

Is it theoretically possible that the Universe is expanding due to additional Big Bang events that have occurred at the same location that the original Big Bang occurred at? Perhaps there has been an ...
3
votes
2answers
103 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 ...
1
vote
2answers
149 views

Why do we presume that the universe has always expanded?

When I read about the universe having always expanded from a 'singularity', I can't help but wonder if that is perhaps not the case. If a singularity is a point at which everything is infinite and is, ...
0
votes
2answers
299 views

Does the edge of the Universe travel faster than the speed of light?

The Universe is expanding faster than the speed of light then does that mean matter at the edge of the universe is also traveling at the speed of light or are ether opposite sides of the universe are ...
2
votes
1answer
116 views

Yet another Question about the expansion of universe

A galaxy 13 billion light-years distant is 94% of the way to the big bang. The universe was 800 million years old when the light was emitted. That galaxy today is traveling away from us at 94% of the ...
3
votes
1answer
113 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, ...
2
votes
2answers
188 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?
5
votes
4answers
223 views

Influences from outside the observable universe explaining dark energy and expansion?

Could some influence from outside the observable universe be causing the expansion?
4
votes
1answer
142 views

How can heavy elements exist when the universe is young compared to the lifetime of a star? [duplicate]

Our sun is said to be incapable of producing heavier elements, and these are thought to originate from older stars dying and going supernova. If our sun is 4-5 billion years old, and has a lifetime of ...
2
votes
2answers
1k views

Will a black hole swallow the universe?

If black holes swallow stuff, will a big black hole eventually swallow the universe? The universe will eventually go dark, because there will not be enough matter to make stars, and all that will be ...
2
votes
0answers
58 views

How to derive the equation for the age of a flat universe with a positive cosmological term?

Can anyone show the steps involved in deriving this equation from the friedmann equation with the cosmological constant involved
7
votes
1answer
133 views

Does the CMB pattern evolve in a human lifetime?

I was thinking, as CMB is a snapshot of a slice of the Universe during recombination, how much the cmb is changing with time ? I mean as we progress in time we look a CMB a bit more faraway each time, ...
1
vote
1answer
72 views

Question on Friedman equation involving cosmological constant

This is the question: By considering both the Friedmann and acceleration equations, and assuming a pressureless Universe, demonstrate that in order to have a static Universe we must have a closed ...
2
votes
1answer
47 views

Where can I find source data for the graph of metric expansion over time, as shown in this ESA web page?

This web page from ESA/Hubble, shows the size of the universe over time. (I know that "size of the universe" is a gross simplification and open to multiple definitions and ambiguity, but this kind of ...
3
votes
3answers
106 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, ...
8
votes
3answers
802 views

Why black holes are extremely cold?

"The most massive black holes in the Universe, the supermassive black holes with millions of times the math [sic] of the Sun will have a temperature of 1.4 x $10^{-14}$ Kelvin. That's low. Almost ...
0
votes
1answer
73 views

SETI search for extraterrestrial life [closed]

In all these years of listening, why hasn't SETI detected anything ? Is there no intelligent life out there or is it too far away to detect ?
0
votes
1answer
58 views

Is the Cosmos a super set of the Universe and any hypothetical multiverse(s)? [closed]

I'm quite lost on the definitions of words like omniverse, megaverse, multiverse, meta-universe, universe, and cosmos. I used to think the Universe and the Cosmos were essentially the same things, but ...
22
votes
3answers
7k views

What would happen to a polished marble statue left in space for a million years?

Consider it doesn't collide with any other objects. Would it be preserved perfectly in the vacuum or would its surface be damaged by anything like UV rays, radiation, gas, space dust, etc?
0
votes
1answer
98 views

what happens when we keep going radially away from earth?

Is the generally accepted belief in the science community, that if one sits in a spaceship and move away from Earth where r (distance between earth and my ship) is continuously increasing, can one ...
4
votes
1answer
204 views

Use of type-I a supernovae as standard candle

Why only type -Ia supernovae are used as standard candle to calculate age of universe and why not type II, type Ib, type 1c ?
2
votes
2answers
85 views

What happens if one day aliens want to talk to us. How can we talk to them? [closed]

Always I wonder about that if some day alien wants to talk to us, then how can we talk to them? They didn't know any of the language on the Earth. What will be the basic building blocks for it?
2
votes
1answer
171 views

If the Universe is Flat, why does it look 3D from our View?

So I know that the universe is flat in a 4D point of view, but what about a 3D point of view? The universe does not SEEM flat from our view, so how can it really be so? Please answer more simple, im ...
-3
votes
2answers
142 views

Is there any way to tell which way is the next universe? [closed]

Is there a observable void outside our universe that can give a clue on how far the next on is? How many universes can surround ours? What does a universes gravity well look like?