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What made the big bang start in the first place? I don't see what could have caused it. What made it burst apart?

Qmechanic
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yishairasowsky
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  • Inflation was what made the big bang burst apart. What had driven inflation depends on the model of cosmology. The inflaton scalar is an example. – BMF Feb 23 '20 at 16:02
  • Yog Sothoth, the blind idiot god. – Slereah Feb 23 '20 at 16:08
  • @Slereah That's Azathoth. – Adam Latosiński Feb 23 '20 at 16:12
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    @BMFForMonica The Big Bang model existed well before the idea of cosmic inflation. – G. Smith Feb 23 '20 at 17:28
  • @G.Smith I never implied the opposite. – BMF Feb 23 '20 at 17:33
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    @BMFForMonica You wrote “Inflation was what made the big bang burst apart.” This is false for two reasons: 1) The Big Bang can happen without inflation. 2) Inflation doesn’t start at $t=0$. – G. Smith Feb 23 '20 at 17:37
  • Possible duplicates: https://physics.stackexchange.com/q/5150/2451 and links therein. – Qmechanic Feb 23 '20 at 17:49
  • @G.Smith the big bang doesn't have anything to say about what happened at $t=0$. I was using the OP's terminology in "burst apart." I assumed by that they meant cosmic inflation, when the early universe grew exponentially larger, and not the event before the big bang. – BMF Feb 23 '20 at 18:00
  • @safesphere every one of my professors made a point about the Big Bang theory saying nothing about what happened at $t=0$ (especially emphasizing that it does not say the universe began as a singularity). Perhaps they left out some finer details--and here I freely admit I am not even close to being an expert--but I have doubts that the Big Bang theory makes those statements about what we can't (as far as I know) experimentally observe. From everything I've read, I am led to believe that the theory offers an explanation for the CMB, isotropic-ness, redshifted galaxies, and other things. – BMF Feb 24 '20 at 06:02

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The Big Bang with modifications is still the mainstream cosmological model because it fits the observations and data using the mains stream physics of our time.

It was proposed because the observations showed that every galaxy was moving away from us and every other galaxy, and the hypothesis of a four dimensional explosion fitted the data originally, with a singularity at the beginning of the Bang. See this for a review.

How the energy of the Bang existed and came to give substance to our universe is one of the open problems and a research question for cosmology theorists.

anna v
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  • Note that the singularity is a mathematical artifact of the model. The theory/model is known to be invalid prior to some very short time after the singularity, $10^{-43}$ s or $10^{-32}$ s or some other time depending on what theory you accept. Prior to that time, little or nothing is known, including whether or not there was a physical singularity. The open question is what happened prior to that time. – garyp Feb 23 '20 at 16:31
  • @garyp sure, . I answered at the level of the question.. I gave a link for a review which also lists the open questions. – anna v Feb 23 '20 at 16:48
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    @garyp There is no such concept as "physical singularity". It has no meaning. In GR, a singularity is a coordinate pointset removed from the spacetime manifold. It does not exist in spacetime, so it is not "physical" for this and other good reasons. Also, if time is quantized (a big if, but still), then there is no singularity problem The first moment of time is one quantum of time, not zero. There is no time "prior to that time". – safesphere Feb 24 '20 at 04:47
  • @safesphere Maybe in your search engine . In mine , when I google "Big Bang phsyics" a large number of references come up on the lines of the model and its continuous redefinitions shown here https://en.wikipedia.org/wiki/Big_Bang . Of course word and ideas are used over and over again, but I have defined "physics". . There is even a sitcom. – anna v Feb 24 '20 at 05:37
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    @safesphere off course you can have your own dictionary and your own language. I just answer in the mainstream language. – anna v Feb 24 '20 at 05:56
  • @safesphere -I just wish some philosopher would come up with a time limit for determining whether time is discrete. (Even just space being made of tiny glass bricks gets my claustrophobia going.) Maybe it would be indiscrete to even request such a determination. – Edouard Feb 24 '20 at 05:58
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    @Edouard Some very sensitive tests have been performed, but so far failed to detect any granularity of spacetime. – safesphere Feb 24 '20 at 06:55
  • Well, altho I know we're not supposed to clog the comment screen with "thanks", I do have to thank you for the update, Safesphere, because, for me, it really is good news! However much it might improve weather forecasting, bring us 4-D television, and even have social applications, the whole idea of "discretion", in every sense, just ain't my style, & physics comes up with (what is for me) a "false alarm" about it once or twice every year! It seriously reminds me of "confinement", which is what people used to call pregnancy (another thing only a minority of people really want)! – Edouard Feb 24 '20 at 19:00
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    @Edouard - http://entangledenergy.net/index.php/time-energy/ I recently saw this website showing time as a product of EM interactions (though it describes it more like an integral function equal to the electric and magnetic) -- paragraph insert " Since time is a product of electromagnetic interactions, time (as we experience it) cannot exist without electromagnetic interactions. This does not mean that sequential “events” cannot occur. It means that events or actions occurring without electromagnetic interactions must consist of perfect randomness (no net event)" – Clock Feb 29 '20 at 18:34
  • @safesphere - see comment to Edouard in case you're interested – Clock Feb 29 '20 at 18:34
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    @Clock It's a very interesting idea, although, since the linked site's "not secure", I don't know whether it represents much institutional research. You'd probably be interested in Barbour's concept (in books & articles on the "Janus Point") of time deriving from gravity rather than from thermodynamics (as in conventional physics): As Barbour (who's solved the "three body problem") may be the most important mathematician now alive, PSE would probably accept questions comparing them, which would draw better-informed opinions than my own. – Edouard Feb 29 '20 at 23:37
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    @Clock The site says it is conceptual just to prompt ideas. The linked page uses some unclear concepts like inherent energy of space. The page points out an already well known suspicion of a deeper relation between time and electromagnetism. For example, aside from confined gluons and elusive gravitational waves, photons are the only ones we know to fly with the speed of time commonly called the speed of light. The deep nature of electromagnetism comes from the U(1) symmetry of spacetime. Gravity comes from relativity of acceleration. How these two symmetries work together is a great question. – safesphere Mar 01 '20 at 00:48