Stack Exchange Network

Stack Exchange network consists of 174 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 [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.

1
vote
1answer
86 views

Hints of pre Big-Bang physics and how to detect them?

The Big Bang model is the current large-scale accepted and tested theory. However, several new physics models or theories propose that there could be a previous Universe. To what extent can be test ...
0
votes
1answer
61 views

How do we know what happened during the Planck epoch era of the big bang?

The Cosmic Microwave Background provides the left over radiation of the big bang. Cosmologists have theorised what happened at the Planck epoch era of the big bang. Where is the evidence of what ...
31
votes
11answers
7k views

How could quantum effects occur in the early universe without an observer?

In inflationary cosmology, primordial quantum fluctuations in the process of inflation are considered responsible for the asymmetry and lumpiness of the universe that was shaped. However, according to ...
-7
votes
0answers
45 views

My theory on the Big Bang , energy and the emergence of space. Please tell me what you think [closed]

The Big Bang did not start with a singularity like a black hole. Entropy only exists when there is something to order. Black holes have an infinitely high entropy. We know that entropy can only ...
0
votes
2answers
61 views

What if humans doubled size… and everything else… could we notice? [duplicate]

After the big bang, everything expanded from a small mass. That expansion is said to be still happening. Imagine if everything observable constantly grew in size. EG. Everything slowly doubled in ...
0
votes
0answers
16 views

Can a no boundary proposal work without the big bang?

In Hawking's no boundary proposal he assumed that the the amplitude for a state A (such as a given 3-manifold) is the sum of all amplitudes for histories starting at a special big-bang-state (like the ...
1
vote
1answer
95 views

How is Inflation able to create an infinite amount of energy?

Follow up to this question here: If the universe is flat, does that imply that the Big Bang produced an infinite amount of energy? As I understand Inflation theory, some time after the Big Bang, the ...
0
votes
0answers
26 views

How big is the universe 1 second after the Big Bang? [duplicate]

In his book Astrophysics for People in a Hurry, Neil de Grass Tyson starts of with the Big Bang and narrates on what (probably) happened within the first moments of our universe. He further states (p. ...
0
votes
2answers
73 views

If the universe is flat, does that imply that the Big Bang produced an infinite amount of energy?

Too much density and the universe is closed, analogous to a sphere in four dimensions: you travel in a straight line and you end up where you started. Too little and you have a saddle: not sure about ...
9
votes
2answers
655 views

What would be the first compound formed in the early universe?

This may sound like a chemistry problem, but I suspect this would have lot to do with primordial nucleosynthesis. After all physics underlies everything. It is believed that several elements were ...
3
votes
3answers
528 views

Is there an exact formal definition of the Universe?

I've read numerous articles about Observable universe, Universe and Hubble volume including Wikipedia ones as well as other sources. After this I wondered. Is there a formal, rigorous definition in ...
-1
votes
0answers
19 views

Could dark energy be the result of residual energy left over from the Big Bang?

I apologize for the horrible question title. I'll try to explain and someone can edit it. I am thinking of the explosion of the Big Bang in terms of the explosion of C-4. Once the C-4 is detonated, it ...
1
vote
0answers
26 views

Is it possible to replicate condition at planck time after big bang by smashing 2 protons really hard?

Because we need to achieve really really high temperature to mimick the condition just planck time after big bang, so suppose we can accelerate 2 protons at extremely close to speed of light and let ...
3
votes
1answer
88 views

How long was the first second?

After the Big Bang all of the matter in the observable universe was condensed into a space that was very small (grain of rice sized). The time dilation due to gravity should have been very large. So ...
-1
votes
1answer
374 views

The infinitely dense point from which the universe allegedly originated - the universe must expand, right? [duplicate]

This is all based on some thoughts this article gave me. Assertions The big bang theory is currently accepted theory about the origin of the universe Infinitely dense implies some kind of material (...
-1
votes
1answer
61 views

Does space expansion increase potential energy, and hence increase mass?

As space expands the gravitational potential Energy increases. So does the potential energy between Atoms and quarks and so on. I have read several times that these effects are so minuscule that they ...
0
votes
0answers
27 views

BBN: How is the expansion rate related to the freeze-out of Neutrons?

I've been making my way through several papers and textbooks on the subject, but they all seem to gloss over this subject: how is the equilibrium of protons, neutrons and photons related to the ...
1
vote
0answers
57 views

Could the horizon problem be explained by a finite universe instead of inflation?

Suppose the universe is finite (either closed or open with a non-trivial topology), any point could be within the horizon of another.
1
vote
1answer
70 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 ...
12
votes
2answers
3k views

When they say that the universe cooled after the big bang, where did the heat go?

Layman here, Stumbling through some physics stack posts and started reading the Wikipedia for the chronology of the big bang. In it, it states The very earliest universe was so hot, or energetic, ...
4
votes
2answers
155 views

Big Bang: what is it exactly that is expanding?

I have read a bit about the Big Bang over the years, but being no physicist I have never been able to really understand what it is about. As far as I know, starting with Hubble we have been able to ...
17
votes
4answers
3k views

Could quantum fluctuations spawn real matter?

Would it be plausible for fluctuations in the QED vacuum to spawn actual matter (such as quarks, electrons the constituents of a hydrgen atom) given enough time and space?
5
votes
1answer
174 views

Where is all the Antimatter?

This is obviously a duplicate of If matter and antimatter... However, it's now four to five years after a swarm of videos were made on this subject. At the time, there was a consensus that the LHC ...
1
vote
2answers
3k views

Which was first, energy or matter in the creation of our universe?

Was it the Big Bang or was it something else that gives us our universe in its present condition? Did it all begin with just pure energy that eventually evolved into simple atoms of matter, that ...
1
vote
1answer
30 views

Effective low energy actions in string cosmology

I wonder why can SUGRA actions be used in string cosmology, since in some cases they are used to model big bang scenarios (for example the pre big bang scenario in chapter 4 of Gasperini's "Elements ...
0
votes
0answers
21 views

Does the universe has a center like a real explosion? [duplicate]

I don't really know much about cosmology but I was thinking one day about the center of the universe. Now 'Big Bang' was the birth of our universe. Then Shouldn't the place (or region of space) where ...
1
vote
1answer
56 views

How was electrical charge formed in the Big Bang?

We know that fundamental particles (Quarks, electrons, etc.) were formed a while after the Big Bang. How was their electrical charge (its value and sign) determined? Was electrical charge present in ...
0
votes
1answer
62 views

How did Big Bang determine the initial conditions of the universe?

My question is that how did the Big Bang determine the initial distribution of the particles and their wavefunctions? In theories like Bohmian mechanics or Many worlds, how was the universal ...
0
votes
1answer
72 views

How far can an atom collapse under gravity? [closed]

Can an atom condense (collapse?) under gravity to a volume less than the nucleus? The Big Bang is the example motivating the question - if the entire mass of the universe is condensing to some ...
3
votes
1answer
61 views

Is Gravity still considered to be part of the “Superforce” which existed at the instant of the “Big Bang”

My limited understanding of the Big Bang is that all the Fundemental Forces (Electromagnetic, Weak Nuclear, Strong Nuclear and Gravity) were originally part of a "Superforce." As the universe cooled ...
1
vote
0answers
125 views

Why am I a Boltzmann brain?

The Boltzmann brain hypothesis states that a big-bang-causing entropy fluctuation is larger than a brain-causing entropy fluctuation, therefore, you are much more likely to be a BB rather than a wet ...
16
votes
10answers
2k 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 ...
1
vote
1answer
32 views

Curvature in space time during Big Bang and present scenario

Space time in the presence of masses is curved. But during the time of Big Bang it's presumed that all the matter in this universe was at a single point, so it must have been super dense and had very ...
0
votes
1answer
49 views

How large was the universe at the start of BBN? How large was it after?

I'm trying to get a handle on the basics of BBN. I've read several authors quote the figure of 17 minutes. So BBN started at 3 minutes and ended at 20 minutes after the start of time. So how large ...
5
votes
2answers
4k views

Does the uncertainty principle violate the law of conservation of energy?

What is the scientific view of the beginning of universe? Quantum fluctuation seems to contradict with the law of conservation of energy. Uncertainty Principle does seem to violate the Law of ...
0
votes
2answers
83 views

Hubble's time and the age of the universe

If Hubble's time is the inverse of a changing Hubble's "constant" and it estimates the age of the universe up to now, since Hubble's parameter is converging to an actual constant value, how can the ...
0
votes
0answers
24 views

what are possible explanations for the larger scale anomaly in Planck satellite's data?

In the Planck satellite's image of the Cosmic Microwave Background (CMB), there have been anomalies, the most important of which is a deficit in the signal at large angular scales on the sky, which is ...
-1
votes
2answers
92 views

Time at the big-bang

At the moment of the big-bang there were no particles with positive rest mass. What is the meaning to aspeak of time then (as a clock can be created only with particles with mass).
2
votes
0answers
85 views

What was the informational content of the universe at the Planck time?

If the energy of $1 \, \mathrm{bit}$ of information is $k_{\small{\text{B}}}T \ln{2}$, then the energy of that bit increases with the temperature of the system. When I try to calculate how much energy ...
43
votes
4answers
8k views

Can space expand with unlimited speed?

According to this article on the European Space Agency web site just after the Big Bang and before inflation the currently observable universe was the size of a coin. One millionth of a second later ...
0
votes
1answer
44 views

Is it possible for another Big Bang event to occur inside our universe?

And if it were, would it constitute an expanding bubble in our universe - with a definite (expanding) surface. That would be nice - none of this irritating "everywhere is the centre and there is no ...
0
votes
1answer
55 views

Can somebody tell me what was the size of the universe and the expansion rate at the big bang? [duplicate]

I want to know the exact numbers and preferably the calculations that gives the size of the universe at the Big Bang and the initial rate of expansion at the moment of big bang. Does somebody know ...
1
vote
1answer
43 views

Do we have enough time for understanding space? [closed]

May be there more big bangs out there... while studding about space i some times think about a bacteria living on my body that may have a life span of 5 seconds if it has logical understating even ...
0
votes
0answers
45 views

How are the temperature, density, and size of the Universe calculated during the first few minutes after the Big Bang?

I'd like to know the assumptions cosmologist use when they give a timeline of temperature, density, and size of the universe from $T=0$ to $T=$ a few minutes later, as Steven Weinberg did in his book, ...
0
votes
1answer
29 views

What does the matter density in density parameter mean?

When we write $$\Omega_m = \frac{\rho_M}{\rho_{\mathrm{crit,o}}}$$ what density does $\rho_M$ refer to? As in, suppose our universe was made with just hydrogen. Then would $\rho_M$ mean just the ...
4
votes
4answers
5k views

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 ...
0
votes
1answer
58 views

How age of universe or galaxy estimated? [duplicate]

How scientist found age of universe as 13.8 billion years and age of Milky Way as 13.51 Billion years? Is there any proof?
1
vote
3answers
132 views

Why can we see the cosmic microwave background radiation?

This radiation (CMBR) is said to have its origin at the surface of last scattering that exposed itself when the big bang universe had expanded for less than a million years. In order to see radiation ...
3
votes
1answer
55 views

How could the early Universe have low entropy when it was so compact? [duplicate]

Entropy of a system can be understood as "the number of states that are macroscopically indistinguishable from the state its currently in". (Sean Carroll, "The Big Picture") Given that the early ...
4
votes
2answers
75 views

What caused neutrinos to decouple at $t=1$ second?

Was it simply that the density and/or kinetic energy got too low, because of expansion? Or was it something about the weak force itself (which I thought gelled around $10^{-10}$s? For the CMB, ...