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3
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0answers
42 views

In the αβγ cosmology paper, how do the authors assume the integral of density over time in the early universe?

In the famous Alpher-Bethe-Gamow paper, the authors say: "it is necessary to assume the integral of $\sigma_n dt$ during the building-up period is equal to $5 \times 10^4 \frac{\text{g ...
4
votes
2answers
240 views

Total Energy of the Universe? [duplicate]

I've heard the total energy is zero, but I've also heard it cannot be said to be zero since there's so much unknown stuff in the universe. Is that true?
15
votes
2answers
1k views

Dumbed-down explanation how scientists know the number of atoms in the universe?

It is often quoted that the number of atoms in the universe is 10$^{70}$ or 10$^{80}$. How do scientists determine this number? And how accurate is it (how strong is the supporting evidences for ...
1
vote
1answer
232 views

Parallel universe and Infinite monkey theorem [closed]

Is the Infinite monkey theorem helpful for determining the existence of the very same our universe somewhere else?
0
votes
1answer
345 views

Are We Living in a Simulated Universe? [closed]

If the universe is just a Matrix- like simulation, how could we ever know? Physicist Silas Beane of the University of Bonn, Germany, thinks he has the answer!. His paper “Constraints on the Universe ...
4
votes
0answers
219 views

Conservation of Energy in the Universe [duplicate]

Possible Duplicate: Is energy really conserved? Why can’t energy be created or destroyed? One of the laws of the universe that dazzles me the most is the law of conservation of energy. I ...
2
votes
3answers
538 views

If everything in the universe doubled in size overnight, would it be noticeable?

By my understanding, if everything doubled in size, such as the Sun and the Earth, and because the space in between them (which is nothing) can't expand, would the gravities greatly change and the ...
4
votes
1answer
420 views

Does the universe obey the holographic principle due to Stokes' theorem?

Does the universe obey the holographic principle due to Stokes' theorem? \begin{equation} \int\limits_{\partial\Omega}\omega = \int\limits_{\Omega}\mathrm{d}\omega. \end{equation} Can this ...
2
votes
2answers
1k views

The meaning of multiverse

A) I am intrigued by the multiverse theory as mentioned in Stephen Hawking's new book, "The Grand Design". According to his theory, one can have different 'universes' in one ultimate existence, a ...
5
votes
3answers
316 views

Is observable universe an explanation against Olbers' paradox?

First of all, let me tell you that I'm not a physicist but rather a computer scientist with a mere interest in physics at nowhere near a professional level so feel free to close this question if it ...
1
vote
1answer
331 views

Crucial Misconceptions about The Universe [closed]

So I am piecing together a school project on the numerous misconceptions of the universe, which I plan to "provide proof against them" with information from various sources (one of the main ones will ...
5
votes
5answers
559 views

Do new universes form on the other side of black holes?

I have four questions about black holes and universe formations. Do new universes form on the other side of black holes? Was our own universe formed by this process? Was our big bang a black hole ...
3
votes
2answers
342 views

(Co)homology of the universe

In this post let $U$ be the universe considered as a manifold. From what I gather we don't really have any firm evidence whether the universe is closed or open. The evidence seems to point towards it ...
2
votes
1answer
158 views

Fractal Cosmology and Misner's Chaotic Cosmology

I have a question pertaining to the ideas behind the considered homogeneity and isotropic nature of the universe (at a grand scale) versus the theory of a chaotic and anisotropy structure of the ...
0
votes
1answer
989 views

How does an inflationary universe solve the Flatness Problem, Horizon Problem and Monopole Problem? [duplicate]

Possible Duplicate: What is the evidence for Inflation of the early universe? I am reading some public science books on inflationary universe, e.g. The Inflationary Universe by A. Guth. ...
8
votes
4answers
512 views

Are we big or small?

How does the size of humans compare to the size of other objects in the universe? Are we among the relatively large or the relatively small things? My very preliminary research suggests that the ...
-2
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1answer
550 views

Is the structural similarity between atoms ( smallest) and universe (biggest) a conincidence. Or there can a reason for this beyond imaginations

Is the structural similarity between atoms ( smallest) and universe (biggest) a coincidence? Or there can a reason for this beyond imaginations? It seems like, if one starts travelling out from ...
2
votes
1answer
80 views

Why does $H_2$ form on such a long time scale?

If we were trying to figure out the time scale for a gas-phase reaction between two hydrogen atoms in a molecular cloud (which has density $~10^4/$cm$^3$), apparently the reaction would happen on a ...
2
votes
2answers
270 views

Did the universe always have 4 space time dimensions?

Is the dimensionality of spacetime in all usual models constant?
3
votes
2answers
388 views

How is it possible to come to a conclusion that Universe is a result of the Big Bang while we aren't able to observe the entire Universe?

-I'm not a religious person so this is not a denial. I'm just trying to understand the most fundamental topic about Universe. -I know the Big Bang cosmological model is not a law but it's a theory. ...
2
votes
4answers
335 views

How was the universe created?

I do not know much beyond high school Physics. Thus, I am asking this question from almost layman's perspective: What, as per the best of our existing knowledge and widely accepted among the ...
0
votes
0answers
55 views

Energy can't be created or destoryed? [duplicate]

Possible Duplicate: Conservation law of energy and Big Bang? If energy can't be created or destroyed then how did the big bang create energy? and if energy can't be created then does that ...
5
votes
2answers
285 views

What really is Spacetime?

What is a good definition on Space, Time and the most specific topic "Spacetime"? Because someone told me that spacetime is the foundation of the entire universe? And also, Is it possible to create ...
5
votes
3answers
542 views

Is the cosmic horizon related to the Big Bang event?

The Universe expands according to the Hubble's law: velocity is proportional to distance. There must be some distance, therefore, at which the velocity reaches the speed of light. This defines the ...
3
votes
1answer
127 views

What would happen in the final days of the universe?

I would like to know the stages of how the universe would end and what would happen and what the possible scenarios are. I understand that eventually all the stars would burn out and that would ...
8
votes
3answers
2k views

Is the total energy of the universe constant?

If total energy is conserved just transformed and never newly created, is there a sum of all energies that is constant? Why is it probably not that easy?
2
votes
1answer
86 views

Why is that the space-time associated with the Earth is not shrinking?

If we apply the Friedmann Lemaître equation to the Universe, we find a critical density $\rho_c$ : if the actual density $\rho$ is under it, the Universe will continue to expand, if it is higher than ...
10
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9answers
1k views

Is it possible all matter in the universe emerges from nothing?

If the Universe is flat and the total energy of the universe can be zero (we don't know if it is, but many theorists support the idea, i.e. at BB initial conditions: t = 0, V = 0, E = 0) then is it ...
0
votes
2answers
104 views

Causal reconnection

Can causally disconnected regions join up again? For example the universe is expanding faster than light creating cosmological horizon, but what if something causes the expansion to slow down and ...
1
vote
1answer
1k views

is gravity always the weakest force [duplicate]

Possible Duplicate: What does it mean to say “Gravity is the weakest of the forces”? Strongest force in nature It is usually taught that the gravitational force is the weakest ...
3
votes
1answer
251 views

Total momentum of the Universe

What is the total momentum of the whole Universe in reference to the point in space where the Big Bang took place? According to my reasoning (and a bit elementary knowledge) it should be exactly ...
1
vote
2answers
1k views

How can galaxies collide if everything moving outwards

If the universe started from Big Bang and everything is expanding outwards and actually accelerating away from each other, than "How is it possible for two galaxies to collide as they all are moving ...
4
votes
1answer
2k views

Is there a finite amount of mass in the universe? [duplicate]

So, I'm not too physics savvy but I am curious to ask. Is there a finite amount of mass in the universe? or is there more and more being created from somewhere or something? If the universe is ...
2
votes
2answers
653 views

Maximum Possible Information in the universe?

I remember hearing about this in one of the programs in discovery science. The physicist claimed that the maximum possible information in the universe is (10)^(10^123) whereas the maximum possible ...
45
votes
9answers
4k views

Is time continuous?

While working on physics simulation software, I noticed that I had implemented discrete time (the only type possible on computers). By that I mean that I had an update mechanism that advanced the ...
4
votes
2answers
2k views

Do we live in a world with 4 or more dimension?

A NOVA show have told the audience that we are live in 3 dimensional world, the world we lived in is compose by 3 element: the energy, matter, space. By the time Einstein have invented the ...
2
votes
2answers
1k views

What is the difference between parallel universe and multiverse?

What is the difference between parallel universe and multiverse? Is it parallel universe or universes?
-3
votes
1answer
251 views

If the universe is infinite, shouldn't I already have been contacted by a time and space travelling doppelgänger?

If the universe is infinite, by virtue of chance it means that every possible configuration of matter must exist somewhere (according to this documentary). Therefore, if we accept that the universe ...
3
votes
4answers
807 views

As the universe expands, why do some things stretch but not others?

I got into watching a video on Olbers' Paradox a few days ago, and from there read about the origins of the universe, its expansion, and so on... it's always fascinated me, but now something about it ...
1
vote
2answers
126 views

Cosmological constant of standard model of cosmology and observational data

I am curious whether the current Lambda-CDM model of cosmology matches well with observational data, especially expansion of the universe. How well does Lambda-CDM defend its established status from ...
2
votes
1answer
709 views

Is the universe linear? If so, why?

Simple question, I'm trying to build a quantum memory system that utilizes the superposition principle to model specific phenomenon I am trying to predict, anyways, my question is this. Is the ...
11
votes
4answers
3k views

Is spacetime discrete or continuous?

Is the spacetime continuous or discrete? Or better, is the 4-dimensional spacetime of general-relativity discrete or continuous? What if we consider additional dimensions like string theory ...
10
votes
4answers
5k views

Size of universe after inflation?

Wikipedia states the period of inflation was from $10^{-36}$sec to around $10^{-33}$sec or $10^{-32}$sec after Big Bang, but it doesn't say what the size of the universe was when inflation ended. ...
3
votes
6answers
1k views

Does gravity slow the expansion of the universe?

Does gravity slow the expansion of the universe? I read through the thread http://www.physicsforums.com/showthread.php?t=322633 and I have the same question. I know that the universe is not being ...
6
votes
4answers
612 views

Is space unending?

Is the space unending, i.e it has no boundaries? If yes, how can a thing exist which is non-ending? Its impossible for me to imagine something like that. Secondly, if its not and has boundaries then ...
3
votes
1answer
127 views

Does cosmic expansion imply the possibility of the universe splitting in half; multiple big-crunches?

There is an event horizon where cosmic expansion leads to superluminal recession speeds for sufficiently distant objects -- the Hubble Volume. 1) Does matter beyond the event horizon affect us ...
0
votes
1answer
159 views

Do wormhole exits require matter? If not, would they change the edge of the universe?

As a layperson who watches way too many theoretical physics and astronomy documentaries, I've seen the folded-piece-of-paper analogy of wormholes a bajillion times. Usually they explain that black ...
1
vote
1answer
320 views

How fast was the universe expanding during the inflationary period?

Compared to how fast it is expanding in the post-inflationary period (now)
-1
votes
2answers
1k views

Regarding possibility of infinitely many spatial dimensions

Recently I was taking a look at a video explaining the existence of fourth spatial dimension and thereupon that infinitely many spatial dimensions are possible. Also it showed that what Einstein told ...
1
vote
2answers
171 views

A question about multiverse

I have a question that I would like to ask here since I'm not an expert or any near to that. Actually I just came up with this question when I was watching The fabric of cosmos. I couldn't find where ...