Big bang Definition and 909 Threads

So DESI 3 year study results were revealed and when combined with other data from other sources it revealed a 3-sigma significant results that dark energy evolves with time, more specifically that it has been decreasing in the last 11 billion years or so...

I grew up in a time when we thought the universe was finite in size - even if unbounded. I am now hearing (from some right here on PF) that scientists think maybe the universe is infinite in extent. But if the Big Bang bubble was once a finite size and expanded (smaller than an atom, big as a...

With experts , like Roger Penrose now questioning the Big Bang Theory, I too am curious about it and other Cosmology issues.

There is a paper called "On nothing" (https://arxiv.org/abs/1111.0301) which goes on to argue that the universe could not have arisen from a state without spacetime (as some proposals do using quantum fluctuations to explain how the universe was born without spacetime) However, there is a...

I have a question that I have been unable to find an answer to. The question is does matter "create" space? Some places I read that space "just is", and matter fills it and creates its gravitational curving. But that something "just is" is supremely unsatisfying as far as answers go. Another...

If gravity is caused by the warping of spacetime - how did gravity compress the mass of the post Big Bang universe? Does said compression indicate the force of gravity exists independent of space time? Was Newtonian gravity responsible for the compression? On the other hand, if spacetime was the...

I'm studying the freeze-out moment of different particles and I have few questions that I can't find answer about the Wimp particles. First of all, the freeze-out temperature of the wimp particles is around 0.4-40gev much higher than 1 mev for the neutrinos. Thus, that means that the freeze-out...

Assumed facts: Galaxies are traveling at velocities that cause very little compression of space. The big bang occurred at one point in space and all matter is moving away from this location. The universe is continuing to expand The farthest galaxies are about 92 billion light years apart or 46...

If we accept the concept that the universe began as a zero-dimensional point, wouldn't that imply that our 3+1 dimensions, or 9+1 / 10+1 dimensions of string theory, emerged at the moment of the Big Bang or some presumably Planck-order time after? Are there any theories on this?

Hi I am trying to reconcile the concept of the Big Bang of occurring "everywhere" (an infinite Universe) - v - the concept of the origin of the Big Bang occurring in a particular compressed state and then expanding? Thanks Martyn Arthur

Suppose the universe were to eventually collapse in a Big Crunch [1]. How closely could the universe's final moments resemble those at the beginning of the universe? Could the universe return to its original state exactly in some kind of "Big Crunch" or "Big Bounce" model? [1]...

*********Disclaimer******** Hi, I want to ask this community about some black hole shinanigans. I've spent some time searching for this topic here because I don't want to be the guy who spams a forum with a question already answered a hundred times over. Since none of the threads I found...

Hi all. Started a conversation with Chat GPT about the big bang, C, gravity, time, thought experiments and other things that I mull over in my brain every few months and it suggested I talk to someone that's actually studied some of the things I asked about especially as things change...

Everything that I’ve researched into this seems to suggest that we know absolutely nothing about the universe at the beginning of the Big Bang event. Could it be that just nothing is there? Could everything in the universe be described by cause and effect, yet cause and effect does not apply...

I apologize in advance if this is a stupid question but... According to some scenarios about the beginning of the universe (namely cosmological inflation), in layman's terms, everything was born out of a quantum fluctuation which caused a violent expansion. In this case, since an expanding...

Can you please express this theory mathematically or through equations? Destiny is the automatically predestined chain or course of events spread throughout the universe that originated from the first cosmic event called the Big Bang. It automatically determined when, where and exactly what...

The time rate of change of neutron abundance ##X_n## is given by $$\frac{dX_n}{dt} = \lambda - (\lambda + \hat\lambda)X_n$$ where ##\lambda## is neutron production rate per proton and ##\hat\lambda## is neutron destruction rate per neutron. Given the values of ##\lambda## and ##\hat\lambda## at...

Does it make sense to anyone? He says our universe is just one in a long line of prior universes. But the big bang was not so much starting from a very small area, but instead results out of a prior universe that had gotten so old that essentially it has no matter, and when there is no matter...

Everywhere on the net, there is no image that the expansion has a departing point, through an expansion in spherical form... Why is that?

I understand, given dark energy, given the current expansion of the universe, given its ~13.8 billion year old age, we calculate the universe is like 93 billion light years across currently. Something like that. But I was listening to something the other day, and when they test the curvature...

Why did it happen? What force would make the universe, which is contracted into a very, very small space, blow outward and expand? Another random question: I've heard that, at least in the inflationary model, the universe started in an amount of space like the size of an atom, or less. How...

In big bang theories where our universe begins from a singularity (ignoring other theories just now), what would happen if the universe didn't begin as a single point but rather began as energy in an uneven shape? Would we be able to tell from the way the universe is now? Do we know that if the...

Please explain how we know that it is space itself that is expanding rather than an expansion due to an explosion such as the big bang. In either case wouldn’t every object appear to be moving away from us? How do we determine that space/ time is expanding? Tex

Are the Big Bang and inflation really needed to account for the large-scale structure of the universe, nucleosynthesis, baryon acoustic oscillations, and the anisotropies of the CMB? Can the universe not begin in an already expanded state and still have all those things happen just the same...

0:00 Gravitational lensing 23:19 Cosmology 33:00 Robertson-Walker spacetime 38:20 FLRW universe 1:01:35 Big Bang

The Webb telescope images show galaxies that are so far away that it takes ages for their light to reach us, so long that we can see galaxies as they were soon after the big bang. How amazing - but hold on. If we came from the big bang, and nothing travels faster than light, how come we are here...

I was reading "Brief answers to big questions" By Hawking, the above pic is from a page of the book, it says that at the time of the big bang there was an equal amount of positive and negative energy, and that the negative energy never went anywhere, the space-time itself is a store of negative...

I am a software trainer and know about as much Physics as I've been able to pick up from the BBC‘s occasional documentaries. I have never even taken a physics course in high school or college so I am an absolute lay-person here with what’s probably a very lay-person question… I was watching...

I am trying to understand / visualise, recognising that the Big Bang is not thought of as an explosion, how the Universe could have come into existence as a 'point' but came into existence 'everywhere'? Is it a concept that such a point was then everywhere, and that the mass of the Universe, as...

Big Bang singularity can never be solved, so Could the "big bang" have been an event where a large sum of highly-dense dark energy converted into mass, and in doing the result is like a nuclear explosion? Could the "big bang" just have been a large sum of matter where the core becomes super...

If the universe was very hot right after the Big Bang how come the entropy of the universe was lower at that point than now? Isn't heat a reason for higher entropy?

I’m getting confused somewhere, and I’d be obliged if someone could pinpoint my error. 1. At or near the Big Bang, everything was so close as to be within each other’s light cones. 2. All parts of the cosmos are now outside of some other parts’ light cones. Therefore, 3. Something traveled...

Dear PF Forum, I've been searching what was the size of the early univese, but I think I might have hit the wall. I read that in the end of inflationary epoch, 10-32 seconds, the size of the universe was as big as a grape fruit? And after that, it seems that I can't find a reference to the size...

So. It was late night, the limpid sky a near cloudless darkness, somewhat lightened by the waxing moon. I being somewhat stoned and looking at the stars and constellations as I sometimes do, and it came to seem to me, in my imagination, that In the spaces between the stars, I was observing (in...

I`m new to physics, but old to the plant ( 70 ) My question is 1) why wouldn`t the universe have evolved , ( change from little / big ), leaving a bit of both , i.e. 2 theories ? 2) Why is the Big Bang always depicted, directionally ?

Quote from cern: "Just after the big bang, the Higgs field was zero, but as the universe cooled and the temperature fell below a critical value, the field grew spontaneously so that any particle interacting with it acquired a mass." Can it go back to zero? If anyone has a comment either way...

Hello, I am a 15 year old who has done research around the topic of why the universe is expanding at an accelerating rate, and how it will come to an end. After years of thought (since I was 11) I have come up with my hypothesis that time itself is accelerating and slowing down, and has been...

When trying to explain from where did all the laws come from, John Wheeler proposed the anaphorism of "Law without law". He proposed that at the "beginning" there were no laws whatsoever, only pure chaos, and that they emerged from randomness and chaos when our universe was created. In his own...

I was thinking about deuterium and that it is not made in stars (too reactive/unstable) and not made in super nova as far as I understand, so I am presuming all of it was made in the first few minutes of the universe and has been with us ever since as it comes from no-where else I am aware of...

Paul Steinhardt: Time to Take the ‘Big Bang’ out of the Big Bang Theory? Paul Steinhard, who co-founded inflationary cosmology, is working on alternatives for inflation in the form of a cyclic, bouncing universe model. In this lecture he compares his model with the inflationary model, and...

Hi and thank you for answering questions on complex subjects like this. I’m a non-scientist who is jealous of your brain capacity! Recently, in a discussion with a chemist, he said the particles appearing from nothing might have been the initial cause of the universe. I’m familiar with the...

I know about these metrics Euclidean metric Einstein manifold Riemannian, pseudo-Riemannian manifolds or Riemannian space Lorentzian manifold Minkowski space Kähler manifold Schwarzschild metric Kerr, Kerr–Newman metrics Reissner–Nordström metric inverse or conjugate or dual metric Induced...

Hubble deep field allowed us to study galaxy evolution from 500 million years onward. Based on my (limited) understanding, I would expect ancient galaxies to contain fewer heavy elements and to have a more "juvenile" appearance, as compared to modern galaxies. Have we actually observed these...

Some physicists (like John A Wheeler, Holger B Nielsen or Ilya Prigogine) have proposed that all the laws of physics (including the most fundamental ones) emerged from a primordial chaos (for example, in the case of Wheeler, he proposed that laws of physics emerged from an initial random and...

I read that our telescopes pointing in any direction show light coming from the early days of the Big Bang (like 13.7 billion years ago). So did the expansion of the Big Bang to "fill" the universe happen faster than the speed of light?

I would appreciate if someone could clarify this simple contradiction with the Big Bang. Assume black holes exist, and are caused by the collapse of large quantities of mass due to gravity. The resultant singularity is so massive that not even light can escape, much less material. Yet if the...

Are there any models, theories or physicists who propose that the fundamental laws of nature come from the initial conditions? Are there any physicists who propose that the most fundamental laws of physics emerged from initial conditions at the origin of the universe? And according to this view...

I understand that the Big Bang was an explosion from an extremely tiny mass with particles and quanta traveling away into empty space (anything out there at the instant of this bang being too far to hit yet). I also understand that some ejecta from the Big Bang have been colliding since then...

Hi all, I was reading this article https://asiatimes.com/2020/11/the-big-bang-never-happened-but-fusion-will/ And I got somewhat confused. As most I've been taught that BB has succeeded in giving most of the cosmological predictions that we observe [nucleosynthesis, formation of galaxies, cmb...

Could you recommend a book to study the big bang theory and the background necessary, mainly in math, to understand the theory rigorously?