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6
votes
2answers
610 views

What are the pros and cons of Einstein-Cartan Theory?

As an alternative to General Relativity, i hear that it can avoid the initial big bang singularity as well as the singularities in black holes, so why does it appear to be talked about so little? If ...
0
votes
0answers
17 views

According to the actual understanding, was the Big Bang a singularity in space or rather in density? [duplicate]

Often in cosmology erroneous pictures are transmitted by the recurrent hearing from various sources or by sentences taken out from bigger discussion, and even by omitting adjectives and the likes. I ...
0
votes
2answers
42 views

Was the singularity just a mini model of our current unvierse? [duplicate]

Did the singularity just "containe" the matter, the energy and the space-time or it created them. If it just contianed them and then the expansion hppened, can we say it was just a mini model of our ...
1
vote
0answers
121 views

Would a cellular-automata universe allow singularities to exist?

It is usually assumed (almost always) that cosmological singularities (like black hole singularities) are impossible and do not exist in the universe. If the universe was like a cellular automata (...
1
vote
1answer
120 views

Is the Big Bang a naked spacelike singularity?

While reading some answers on similar topics, I was wondering about the nature of the Big Bang singularity in the standard cosmological model. I know it's a spacelike singularity that have a ...
0
votes
1answer
145 views

Are physicists still ignorant of the existence of real singularities?

(1) Is the gravitational singularity (or space-time singularity) the same as the black hole singularity? (2) The wikipedia page says Physicists are undecided whether the prediction of ...
0
votes
2answers
61 views

Mass and Expanding Space

1) space is expanding at an increasing rate, therefore things are getting farther from each other and therefore increasing in velocity. 2) the faster an object moves relative to another, the more ...
0
votes
2answers
68 views

In what sense the scale factor $a(t)\to 0$ lead to the big bang singularity?

How do we understand that the limit $a(t)\to 0$ (where $a(t)$ is the scale factor) lead to a spacetime singularity? Is it by substituting $a(t)$ in the FRW metric and concluding that space makes no ...
0
votes
1answer
137 views

What is the difference between a quantum fluctuation and a singularity in the beginning universe?

I am sure this is a naive question that shows my lack of sophistication in physics but I keep reading "the early universe was a "singularity", on the other hand ..... I also see quantum fluctuation ...
1
vote
1answer
174 views

Big bang singularity in an infinite universe [duplicate]

If the spacetime of the universe is infinite now, then it must have been infinite at every point in its history, right? How then can Big Bang be an expansion of space and time? Can somebody show the ...
1
vote
1answer
352 views

How can an infinite universe be dense at the big bang? [closed]

If the universe is infinite, it always had to be spatially infinite since at the big bang. And I'm assuming that cosmologists don't think that a Big Bang singularity actually occur in the real ...
0
votes
1answer
622 views

What was (physically) present within the mass of initial singularity?

I've been trying to figure out what scientists believe to have been infinitely condensed in initial singularity. It is claimed that all mass existed before the big bang, this leads me to many ...
1
vote
1answer
337 views

Why does the big bang not violate Heisenberg's uncertainty principle? [closed]

I have been doing some reading about the start of the universe and some sources would state that the universe started as a singularity. But how does this not clash with the uncertainty principle?
0
votes
0answers
45 views

Is time unbounded in the future direction? [duplicate]

Time likely had a beginning, because of the big bang theory. But will time ever end?
2
votes
1answer
116 views

Why do singularities either lie completely in the future or completely in the past?

In his book "A Brief History of Time", Prof. Hawking goes on to state that singularities either lie completely in the future or in the past. What does that mean in layman terms and why does it so ...
1
vote
1answer
149 views

Space-time infinite [duplicate]

My apologies if this is a duplicate question. I could not find it. Why do we think space-time itself started at the BB? Or to word it another way, could space-time have always existed infinitely in ...
0
votes
2answers
68 views

Penrose Theorem: Comparing 2 different physical quantities?

Wikipedia says- Penrose's theorem is more restricted and only holds when matter obeys a stronger energy condition, called the dominant energy condition, in which the "energy is larger than the ...
1
vote
2answers
3k views

Correct interpretation of the Borde Guth Vilenkin (BGV) theorem?

I recently watched this debate between Sean Carroll and William Laine Craig on the topic of theism. At 8:29, Dr. Craig presents his interpretation of the BGV Theorem, and claims it implies the ...
0
votes
1answer
91 views

Potential Distant Future Reversal of Universe's Dark Energy Scalars?

Assuming the most probable universe topology/parameterization -- a infinite flat / open universe following the Lambda-CDM model -- and most possibilities postulated on the long term evolution of such ...
1
vote
2answers
225 views

“Before” the Big Bang was the Universe really compressed into a mathematical point? [duplicate]

A couple of weeks ago a teacher of mine (I'm taking mathematics) was giving a final inspiring lecture about how fundamental Math is to every possible universe. During the lecture though, he said that ...
1
vote
4answers
2k views

Where does the matter and energy go in a black hole?

Is it possible that when matter and energy enter the singularity inside a black hole, that it all re-appears at the big bang? Some say that black holes will eventually swallow all the matter in the ...
0
votes
1answer
107 views

Question on Big bang

Why was it necessary to think of the existence of a singularity during the big bang? As per the current theory, during the big bang, the universe had an infinitesimally small radius, and just after ...
0
votes
1answer
260 views

Big Bang not really the beginning of a completely new universe? [closed]

From what I know about the origins of the universe and the big bang, it is stated that it all started from an intensely hot and dense mass. This sounds like a singularity to me, which means a black ...
0
votes
1answer
635 views

Could the uncertainty principle create matter in the Universe?

According to quantum mechanics we have the uncertainty principle: $$\Delta E \ \Delta t \geq \frac{\hbar}{2}$$ Near the beginning of the Universe $\Delta t$ is very small and therefore $\Delta E$ is ...
0
votes
2answers
59 views

How Can a Singularity contain different things? [closed]

According to the Big Bang model, space and everything in it was squeezed into a infinitely small point which subsequently expanded. But if everything is squeezed into a point of zero size than there ...
1
vote
1answer
199 views

Describing the shape of a singularity

Hawking and Ellis write about the difficulty of describing the shape of a singularity when presented with a manifold that has curves of finite length that don't reach a point in the manifold. [...
-3
votes
1answer
158 views

It's a Hypothesis about the Beginning of the universe [closed]

Let's take a piece of paper and plot a couple of dots in it. If we shrink the paper infinitely, at some point it would reach a state of infinite density, that is; a Singularity. But even at that state,...
-1
votes
1answer
95 views

Singularity - Origin Point

How can it be said that the real beginning of the real universe involved a "singularity of zero size and infinite density of mass" when no space existed at all to define any density and when nothing/...
2
votes
0answers
27 views

The universe is said to have begun as a singularity, but how do we know nothing else existed? [duplicate]

When I imagine the big bang, I first imagine a tiny ball surrounded by black void. Then the ball explodes and the universe begins. I assume most physicists have the same basic idea. But how do we ...
1
vote
3answers
616 views

The Big Bang theory hypothesis

Is there a simple way to state the hypotheses of the Big Bang theory? I have the impression that the Big Bang singularity is merely a consequence of Freedman equations. Could somebody clarify what ...
4
votes
2answers
522 views

Age of the universe and the singularity at the Big Bang

Using the standard model of cosmology we calculate the Hubble time to obtain an estimate of the age of the universe. This model assumes a beginning of time in the past. But that point is a true ...
2
votes
3answers
2k views

Why is the singularity of the Big Bang not considered to be the center of the Universe? [duplicate]

If the universe is expanding, then at some time in the past, it must have started from a single point but why this point is not the center of the Universe. Just like the singularity of black holes is ...
0
votes
0answers
35 views

Did spacetime curve infinitely about 13.7 billion years ago? [duplicate]

GR/Big Bang Model implies that there was a singularity about 13 billion years ago, in which all the matter and energy along with the observable universe (or perhaps, the entire universe) was contained....
0
votes
2answers
415 views

How could the “Big Bang” singularity have actually expanded? [duplicate]

We have mountains of evidence about singularities and how they work, and we have mountains of evidence that the "Big Bang" was the origin of the universe as we know it. But if compressing enough ...
104
votes
3answers
18k views

How come some people are claiming that the Big Bang never happened?

A news story is going viral on social media networks claiming that two physicists have found a way to eliminate the Big Bang singularity, or in layman's terms (as claimed by many sensationalist news ...
19
votes
6answers
2k views

Interpretation of a singular metric

I'm interested to find out if we can say anything useful about spacetime at the singularity in the FLRW metric that occurs at $t = 0$. If I understand correctly, the FLRW spacetime is a combination ...
4
votes
1answer
229 views

A true singularity at $t=0$, coordinate independent Big Bang

Consider a flat Robertson-Walker metric. When we say that there is a singularity at $t=0$, clearly it is a coordinate dependent statement. So it is a "candidate" singularity. In principle there is ...
3
votes
0answers
55 views

What will happen to a naked singularity during the Big Rip? [duplicate]

I apologize in advance if some concepts I use are vague, but I am just an enthusiast. I have read that the Big Rip will not rip off black holes because the event horizon will become equal to something ...
1
vote
1answer
375 views

How can the Big Bang singularity exist in spacetime if it has zero volume? [closed]

How can the Big Bang singularity exist if it has zero volume? I tried googling to find the answer - no help. Can someone give a general idea how can the big bang singularity exist even if it has zero ...
2
votes
1answer
227 views

The universe appears to have a lower bound in the time dimension, why not an upper bound?

The Big Bang looks like a lower bound to the "size" of the universe in the time dimension. Could it also have an upper bound, some furthest point in time from the Big Bang?
3
votes
2answers
384 views

Could the singularity that gave rise to our universe be past-eternal?

Are there any compelling models that include a past eternal singularity that ultimately gave rise to our universe? Does the "no-boundary" hypothesis that utilizes imaginary time have past eternal ...
5
votes
1answer
1k views

Reconciling “The Big Crunch” with the 2nd Law of Thermodynamics

Assume "The Big Crunch" scenario (the universe will collapse to a singularity). In this case, I think of the entire universe as an isolated system; in the "Big Crunch" scenario, it seems to me gravity ...
1
vote
2answers
477 views

Did the singularity really existed in the begining of the universe?

I read in Hawking's brief history of time the following: The final result was a joint paper by Penrose and myself in 1970, which at last proved that there must have been a big bang ...
0
votes
1answer
141 views

Temperatures at extreme densities

Cosmology (and astrophysics) talk about the "initial singularity" (IS, became the big bang) and "black hole singularities" (BS, inside black holes), and these appear to be quite different: The IS is ...
2
votes
1answer
316 views

Why are black hole singularities stable?

The Friedmann equations says that huge matter densities lead to huge expansion rates. In Newtonian gravity, two massive point particles separated by an infinitesimal distance will experience an ...
22
votes
7answers
3k views

Given that matter cannot escape a black hole, how did the big bang produce the universe we see today?

Extrapolation of the expansion of the Universe backwards in time using general relativity yields an infinite density and temperature at a finite time in the past. If the matter contained within our ...
8
votes
2answers
534 views

Is there a consensus on the fate of our universe?

We all know that our universe is inflating from what is known as the Big Bang. However, will our universe continue to inflate at the current rate? Or after reaching a maximum size, will it collapse in ...
21
votes
2answers
6k views

How can something finite become infinite?

How can the universe become infinite in spatial extent if it started as a singularity, wouldn't it take infinite time to expand into an infinite universe?
5
votes
3answers
1k views

Do singularities have a “real” as opposed to mathematical or idealized existence?

I was thinking of, for example a Schwarzchild metric at r=0, i.e. the gravitational singularity, a point of infinite density. I realise that there are different types of singularities--timelike, ...
19
votes
6answers
2k views

Why did the universe not collapse to a black hole shortly after the big bang?

Wasn't the density of the universe at the moment after the Big Bang so great as to create a black hole? If the answer is that the universe/space-time can expand anyway what does it imply about what ...