Questions tagged [big-bang]
According to the current cosmological theories, it's the model that explains the early life of the universe, starting from a rapid expansion of hot and dense matter.
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If the Big Bang started in a state of low entropy then shouldn't the Big Crunch be in a state of low entropy also?
I recently read that:
What our current level of thermodynamics does tell us though is that if there is such a thing as a Big Crunch, the universe will look a lot different as it heads towards ...
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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 ...
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What is the hypersurface that represents the particles horizon?
I need to clarify a detail about the particles horizon (also called the causality horizon, not to be confused with the event horizon). For simplicity, consider an euclidian static universe, with a ...
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How early did primordial oxygen form?
It has been suggested liquid water could exist 10-17 million years after the Big Bang, warmed by the CMB instead of stars. Would Big Bang nucleosynthesis produce oxygen that soon? (Empirically, the ...
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How close can we get to duplicate the conditions of big bang?
The particle accelerator has attempted to smash gold nucleus together to reproduce the moment of or after big bang, how close can we go and how to verify if that result is not a fluke? Can we create a ...
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Is there any credible evidence for big bang? [duplicate]
The big bang model is first discussed when the people witnesses that almost every galaxies are speeding away from each other suggesting that at one point in time or more accurately at $t=0$ everything ...
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Have we found Absolute Time with Big Bang?
Since we found $T_0$, the origin of the line/ the absolute zero of ..Time with the Big Bang, can we consider that the absolute time, the same as we do with absolute temperature?
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Is the observable universe an absolute? [closed]
A short summary of a question difficult to easily describe:
Assume objects from the begining of the universe are at a fixed distance at T equals 0 when the universe is created. These objects become ...
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How widely accepted/supported is inflation theory? [duplicate]
To the less well acquainted, inflation theory seems like a rather far fetched proposal. It makes very specific claims about the earliest moments of the universe, without being explainable in terms of ...
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question about other dimensions
The Big Bounce theory says that before the Big Bang there were other Big Bangs over and over. For example, the universe would have a Big Bang within it and then this new mini-universe would expand, ...
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How did the big bang create space and time? [duplicate]
Does the big bang theory state that space and time originated after the bang? So, was the singularity was converted into the vast space plus time?
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How can the universe expand if there is gravitation?
We live in an expanding universe - so I'm told. But how can that be possible? Everything imaginable is attracted by a bigger thing. So, why can't gravitation stop the expansion of the universe? I know ...
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Did quantum fluctuations create matter and energy out of nothing?
I found a popular science article explaining that the existence of the Higgs particle can be interpreted to mean that matter and energy are created by quantum fluctuations of nothingness (i.e. the ...
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Heavy Ion-collision and Big Bang
I have read heavy ion-collision can be used as a source of information about early universe but I don't know how these two are related. I would be glad if someone gives me a reference about this topic ...
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Why didn't the big bang collapse inward into a black hole? [duplicate]
After all, the density of matter in the first fraction of a second was much higher than that found in any star, and dense matter is supposed to curve spacetime strongly. At sufficient density there ...
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Can we determine the origin of the universe?
I'm not a fan of religious theories, but I keep asking myself all these following questions:
Assume that nothing is created, everything is transformed and the big bang at the end of the period of ...
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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 ...
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A question about a proposed "big bounce" [duplicate]
This may be a silly question, but it popped into mind while reading this article on Scientific American: Did the Universe Boot Up with a “Big Bounce?”
One of the early bits of evidence for Mirror ...
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Black hole and critical mass? [closed]
I keep hearing about big bang, but there are no white holes and no black hole has been observed exploding. So is there a point in which a black hole reaches critical mass?
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What if the Big Bang was an accident? [closed]
Is it possible that the Big Bang was the product of a fission of an infinitesimal particle produced by an advanced civilization that destroyed part of the universe, and that there are other parts of ...
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Have conservation laws stayed constant since the Big Bang?
By conservation laws I mean quantum number conservation, such as baryon and lepton numbers.
As far as I know, we have a reasonable confidence that experimental data confirms a lot of features of our ...
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Is this explanation for the Universe's low entropy at its origins plausible? [closed]
I've been thinking about this, and it may sound very ludicrous (and it probably is), but I may have come up with a proto-explanation for it. I hope I won't come across as some misinformed perpetual ...
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Did the universe really start with a single point? [duplicate]
I read everywhere the famous, but offhand statement that "the universe began from a single point" and this bugs me because that surely isn't true.
My understanding has always been that this was an ...
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Origin of time or origin of space-time? [closed]
Are there alternate theories or models that contradicts the idea that big bang is the origin of time ?
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Why is the possibility of the universe having a centre around which everything orbits not considered feasible?
I'm sure there is some kind of reason as to why this isn't considered as a legitimate theory but upon giving it though it seemed to make sense to me. I figure if all gravitational orbits are ...
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Why is it said that photon-wavelengths have increased by a factor of 1000 since our universe became transparent to light?
After reading several explanations for the so-called "Hubble-radius", and still being confused, (as I reckon are some of the folks who tried to answer THAT question !!), I have a related question, ...
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Is the universe actually formed according to the big bang theory? [closed]
Big-Bang pretty much explain the origin of universe, but still many people don't believe it. Isn't it possible that our universe come out of a white hole which have been pulled out from a black hole ...
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How would cold neutrinos get trapped by stars?
Continuing on from the cool physics Q&A'd on the threads Where are all the slow neutrinos?, Is it possible that all "spontaneous nuclear decay" is actually "slow neutrino" ...
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What does the cosmic neutrino background look like today, given that neutrinos possess mass?
This question is inspired by (or a follow-up to) the threads Where are all the slow neutrinos? and Is it possible that all “spontaneous nuclear decay” is actually “slow neutrino” induced?
The cosmic ...
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Is it possible to dumb down the idea that "Time didn't exist until the big bang"? [duplicate]
So, I've asked questions before that have been met with "Time (and our laws of physics) didn't exist before the big bang" and other answers to that effect. This is massively confusing to me, for ...
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How do we know what happened during the Big Bang?
Any data that we have on the Big Bang comes from the cosmic microwave background (CMB) which was created about 380,000 years after the Big Bang. From there we have been able to calculate what the ...
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What is significance of density of the universe if it changes?
So theories of expansion of the universe (before dark matter and energy) said that the ultimate fate of the universe is based on the density of the universe and this being compared to the critical ...
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Big Crunch, then new Big Bang = exact same Universe? [closed]
If after a Big Crunch, the new singularity explodes in a Big Bang, would we get the same Universe all over again? Since black holes retain all the information they've stored, would we get an exact ...
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How can we look back at our Universe 13Billion years ago? [duplicate]
I read this article on Space.com and I quote "As far as we know, that's as far [back] as we can see — we get an image of the universe as it was when it was about 389,000 years old," So what I wanna ...
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Could a pocket universe be birthed out of the negative pressure in our universe?
I have just recently started learning about inflationary cosmology so I don't know much about it. But from my understanding, the theory says the big bang was started by the expansion of a small region ...
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In the classical inflation and big bang theory how can the universe grow to infinity?
Some astronomers make the conjecture that the universe is actually infinite in extent (which is a bad manner of expressing, I know). If so, how could it grow to this size in the classical theory of ...
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Qualitative picture for a Lemaître's Cold Big Bang theory
Warning: please, consider this question to be motivated by historical curiosity or as an exercise in model-building. I believe this cannot be considered non-mainstream physics as it was very much ...
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Why is acceleration of expansion of space unexplained?
I didn't know how to better phrase the question so here we go.
It says that the farther we see from our galaxy the faster the other object seems to be going away (accelerating).
My common sense ...
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Should entropy define order rather than disorder? [closed]
Disorder, as I understand it, is basically a measure of entropy. This does not seem correct to me, and appears to be a result of our macroscopic bias.
Not only does the beginning of the universe ...
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What is Hawking's, "No Boundary Conditions"? [closed]
In his "No Boundary Conditions", is Hawking stating that time is eternal?
And what is the difference between Real Time and Imaginary Time?
Is he saying there are two different arrows of time, and ...
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How do we filter out radiation from galaxies from the cosmic background radiation?
When a whole sky view is done to get a picture of the cosmic background radiation the radiation from our Galaxy is filtered out, and we are left with a picture which show radiation coming, more or ...
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Hubble's constant measured by observer approaching light speed
I recently read about expansion of the universe and I can't figure out if Hubble's law (and other models of expansion of the universe) is compatible with the theory of relativity.
My question is: In ...
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Can we see the past view of our galaxy while observing in the sky because of the homogeneous structure of our universe?
As a sense, we think that simple speed addition should work ($V_1+V_2$) for all references but we know today that universe does not match our this sense. We cannot exceed the speed of light in any ...
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Why does the flatness problem (of the universe) present a fine tuning problem?
The Friedmann equation can be written
$$|\Omega-1|=\frac{|k|}{a^2H^2}$$
In a period where the universe is decelerated $a^2H^2$ becomes bigger as we extrapolate into the past.
We know $|\Omega-1|$ ...
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Hubble time and age of the universe
I'm having trouble with the following derivation of the 'age of the universe': https://i.stack.imgur.com/CvbwK.jpg
The parts I'm struggling to conceptualize is what a 'universe expanding' means, and ...
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Gravitational entropy [duplicate]
In the beginning (big bang), mass was evenly distributed (if you consider an elementary particle as an extended object, like a circle on a very thin cylinder, with a radius near the Planck length, but ...
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What is the difference between the Big Bang Model and the Λ-CDM Model?
If I'm going to write about "The Consensus Model of Cosmology" should I include Big Bang Model or should I go with just the $\Lambda$-CDM Model?
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How can Big Bang happen without time?
I had recently watched a video and he says big bang could have happen by the slow collision rather than a fast collision. But I know that there was no time before the big bang and fast and slow are ...
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How did gravity exist before mass?
I'm brushing up on my Big Bang, and I noticed that, apparently, although gravity is the first force to split from the original "superforce", mass does not appear on the scene until after the second ...
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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 ...
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