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2
votes
0answers
54 views

Adding up gravitational fields of infinitely many objects?

I'm reading a book introducing gravity and find something I don't understand. Please check the attached image. The sentence in red bracket claims that if one adding up gravitational fields of ...
2
votes
1answer
62 views

Black holes as universal “anchors”? [closed]

I'm not a Physicist, but was watching a program about black holes. As I understand it time and space "stop" at the singularity of a black hole, which made me think of a black hole as some kind of "...
0
votes
0answers
46 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
117 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 ...
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 ...
3
votes
3answers
3k views

What happened during the Planck Era of the Big Bang?

If you look at a big bang timeline before 10 to the -43 seconds you can see Planck time - ???? So I googled it and was met with Before 1 Planck Time Before a time classified as a Planck ...
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
43 views

Is there any possible evidence that can give us insight into what happened exactly at the Big Bang/why it happened?

It's mostly well accepted today that the Big Bang was the reason for today's universe, mostly due to the expansion, the cosmic microwave background etc. and mathematically the FLRW metric supports it. ...
0
votes
1answer
1k views

Is there a place in the universe where time doesn't exist?

I've been reading that, all laws of nature and the universe stop existing at a singularity. So where there is a singularity, there cannot be time. A singularity is created when a property of a system ...
-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
votes
3answers
236 views

Does infinite actually occurs? [closed]

I tend to deny any claim that $X$ is infinite, where $X$ is anything from our observable universe. For instance: The number of grains of sand on Earth is infinite? No, it is a big number but not ...
7
votes
2answers
8k views

Obtaining a copy of Hawking's Ph.D thesis - Properties of Expanding Universes

Due to its popularity, I am interested to know the 4 chapter titles and topics covered in S.W. Hawking Ph.D, Properties of Expanding Universes. I also ask this because that thesis is hardly available.
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 ...
1
vote
2answers
427 views

Can a sufficiently large black hole be singularity-free?

This came to me after reading that a black-hole that has the mass of the observable universe will also have an event horizon that covers the observable universe. Since the definition of a black hole ...
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....
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
228 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?
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 ...
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?
21
votes
5answers
7k views

Does red shift evidence necessarily imply that the universe started from a singularity?

We are taught that the universe began as a singularity - an infinitely small and infinitely dense point. At the beginning of time there was a 'Big Bang' or, more accurately, 'Inflation'. The main ...