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A little-scale survey

  1. Jan 28, 2005 #1
    Hi people, I'm new here and I would like to know your opinion about which theory explains best the origin of matter in the universe, giving as much information as possible about it, as I'm doing a little research project.

    Please try to answer these questions when posting your reply:

    - Which theory is more likely to be true? Which one is more close to the facts empirically proven?

    - Is there anything that can explain where does matter exactly come from?

    - Do you think it is philosophically possible that the whole universe came out of nothingness?

    - What did really happen in the Big Bang?

    - Why do so many people refute theories without offering an alternative?

    Well, thank you very much for yur attention, every single piece of information I can get will be very helpful.

    [Sorry for my bad English, but I'm from Spain (for those who may not know it's a country in Europe, below France ;-)]
     
  2. jcsd
  3. Jan 28, 2005 #2
    Spain? Never heard about this country :tongue2:
    I would say that actually the most popular theory is the Concordance Model, aka Standard Model, that has like one of its pillars the phase called Inflation, where the Universe grew at an exponential rate. But well, there are many different models of inflation (many, many). The origin of matter? At least in two of these models (new inflation and chaotic inflation), the origin of matter is explained this way: to the inflaton field we can associate one quantity called the inflaton potential. Nearly at the end of inflation, the inflaton oscillates around the minimum of its potential, and during this oscillations transfers energy to some quantum fields, and particles are created in these quantum fields. How the inflaton transfers energy to those fields? Well, that's a question for another day, I'm afraid...

    Catalan Welcome: Hola noi, jo sóc de Barcelona, ja veus que petita és l'Internet. He estat uns quants cops a Granollers. A veure si ets capaç de portar gent de Catalunya aquí a PF, jo no sóc capaç...
     
  4. Jan 28, 2005 #3

    saltydog

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    Is is all a matter of 'phase-transition'?

    Does matter precipitate from energy in a phase-transition?

    Universe? Does it emerge in a phase transition from some pre-existence? I don't think it was from nothing, just an existence we don't have a good grasp of yet.

    Big Bang? When a system is at its critical point, the smallest change can cause a 'catastrophe', and abrupt change leading to a qualitatively different state. In this view, the pre-existence was pushed past its bifurcation point, causing a phase-transition leading to a catastrophe we call the Big Bang.

    No, I don't have empirical evidence for this but I'm optimistic that any other theory proposed will encompass these principles.

    SD
     
  5. Jan 28, 2005 #4

    ohwilleke

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    I steadfastly refuse to believe that Spain exists. The merger of Castille and Aragon was just a myth. ;)

    Which theory is more likely to be true? Which one is more close to the facts empirically proven?

    Some version of a Big Bang theory is very likely true, but while the current "concordance model" (bascially Big Bang with expansion, cosmological constant, 4% normal stuff, 70% dark energy, remainder dark matter) may fit the current best evidence, I doubt that it will hold up without modification.

    I expect that the dark matter will turn out to be actually a result of incorrect equations of gravity where a MOND like theory of gravity in fact governs, and that corollaries of this theory will also show an absence of dark energy. I think we will discover some form of intrinsic redshift in quasars (resulting in adjustments of cosmological data) and a somewhat different story regarding inflation than current theory suggests.

    Is there anything that can explain where does matter exactly come from?

    No.

    Do you think it is philosophically possible that the whole universe came out of nothingness?

    Anything is philosophically possible. If vacuum energy can spontaneously create particles and anti-particles, this is hardly more radical.

    - What did really happen in the Big Bang?

    A quantum fluxuation looks pretty plausible to me. Also, I doubt that the observable universe is really the "whole" universe. I suspect that we are not the only universe which exists in the cosmos.

    - Why do so many people refute theories without offering an alternative?

    Because it is easier, and refuting does not always logically require an alternative. In the same vein, it is much easier to say that the universe is older than 10,000 years, than it is to say exactly how old the universe actually is.
     
    Last edited: Jan 28, 2005
  6. Feb 4, 2005 #5

    Nereid

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    Welcome to Physics Forums, Mr Blonde!

    To take a slightly different tack from those who've responded (well) to your questions so far; IMHO, part of the answer is "because that's the way science in the 21st century works, and as it's given you, Mr Blonde, a PC and the internet with which to post your questions to a global audience of PF members, *it works*."

    For the philosophy and interpretations beyond the domain of the equations (etc) which are the concordance model (or whatever), isn't it nice to chat? Aren't the word pictures we paint satisfying (or not)?

    Maybe I'm just too much of a forastero; why do the word pictures give you comfort (or not)?
     
  7. Feb 6, 2005 #6

    turbo

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    - Which theory is more likely to be true? Which one is more close to the facts empirically proven?

    The theory most likely to be true is the one with the fewest "fudge factors" (an English idiom for "excuses for not conforming to observation"). The concordance view (Big Bang) needs huge amounts of invisible matter, undetectable energy, and early inflation (also unexplained) to remain viable. Don't bank on this model - there are way too many problems. Big Bang enthusiasts will accept any number of impossible or improbable "fixes" to keep the theory alive, but it has essentially been dead for years. It will be embraced and taught for a very long time, much like the "orbiting planet" model of electrons in atomic structure in basic chemistry, but it is wrong .

    - Is there anything that can explain where does matter exactly come from?

    It depends who you listen to. The Big Bang model posits the creation of equal amounts of antimatter and matter with just a "slight" imbalance in their ratios (or an early selection factor) that explains the current domination of matter. I don't find it convincing, but you might. If you demand perfect symmetry and a beginning to our Universe (like the Big Bang), you might have trouble with this.


    - Do you think it is philosophically possible that the whole universe came out of nothingness?


    No. It is a human conceit to want to make the universe have a "beginning" and an "end". I firmly believe that extrapolating redshifts back to a "beginning" is a huge mistake. Edwin Hubble was unwilling to make that leap, and I expect that his caution will be vindicated.


    - What did really happen in the Big Bang?


    Was there a Big Bang? See above.

    - Why do so many people refute theories without offering an alternative?


    It is easy to nay-say (another English idiom for simple refutation without any logical foundation), especially for proponents of the concordance view. It is very difficult to be heard when you propose reasonable alternatives to the concordance model, because there are lots of people who will gladly bash you for daring to challenge their preconceptions.
     
    Last edited: Feb 6, 2005
  8. Feb 6, 2005 #7

    Chronos

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    The big bang model is currently favored because it better predicts all observational evidence to date than any other model.

    Matter vs anti-matter? Obviously there is some kind of symmetry breaking that favors one flavor of matter over another. Otherwise, there is no matter and this is contrary to observation. Basically matter came into being because the initial energy density was so enormous it was forced to condense into matter. It is akin to the way high humidity causes dew to form when the temperature drops.

    Is it philosphically possible for something to arise from nothing? While not philosophically possible, it is scientifically possible. It's called quantum theory. And our universe is definitely finite - it has a particle horizon. It may be bigger than we can see [~13.7 Gly], but regions beyond our ability to observe have no scientifically meaninful consequences.

    Why do so many people refute theories without offering an alternative? You can no more refute a theory than you can prove it. You can only assign them probabilities.
     
  9. Feb 7, 2005 #8
    Thank you very much! I didn't expect so many answers really! Well, I'll keep posting my doubts and giving my opinions.

    Let's keep this forum going!
     
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