Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A Problem with the Big Bang

  1. Nov 3, 2007 #1
    I stumbled across a creationist site today (http://www.wasdarwinright.net/bigbang.htm). Almost all of their objections to the Big Bang have been solved except this:

    (c) Confusing supernova. Type Ia supernova explode with a known intensity, and therefore their distance should correlate well with the observed red shift. However, some supernovas at great distance have been found to be brighter than expected, and some nearer have been found to be dimmer. The preferred solution is that the cosmological constant, (the repulsive force sometimes called dark energy) was at first weaker than thought when z <1.5, but then kicked in with a vengeance and today the universe is thought to be expanding faster than expected with values of z >1.5. However, this leads to many more anomalies. Other observations suggest that the cosmological constant is either zero or very small, but nowhere near enough to account for the expansion of the universe that the big bang theory requires. Alain Blanchard of the European Space Agency stated that data collected from the European XMM Space satellite ‘leaves little room for dark energy.’ (ESA News release 12 December 2003).

    What does this mean for the Big Bang?
     
  2. jcsd
  3. Nov 3, 2007 #2

    Garth

    User Avatar
    Science Advisor
    Gold Member

    Hi pbethala and welcome to these Forums!

    I respond to your post with the assumption that you are not one of the six-day creationists whose site you have stumbled upon, otherwise I am wasting my time!

    There are indeed questions to be asked about the Mainstream [itex]\Lambda[/itex]CDM (Big Bang) model, however they may well have straight forward answers, but even if not then that would not be fatal to the whole theory but simply adjust timescales and the suchlike here and there.

    You will find most of these issues discussed elsewhere on these Forums, we question to understand, whereas you will find 'Creationists' tend to ask a question about the 10% evidence where there seems to be a problem, and choose to ignore the 90% evidence which gives a solid foundation for the standard view, in order to overthrow the whole works.

    For such people I would also point out the Old Testament Bible treats the Earth as flat (Psalm 19) and fixed in space (Psalm 93:1 & Psalm 104:5), are they also going to refute Kepler and the Apollo photographs of the whole Earth?

    If gravitation from matter and radiation dominate the early universe then it is expected to decelerate according to the well tested theory of General Relativity. This would mean standard candles would be brighter than expected with a linear expansion.

    In 1998 Supernove Type Ia were seen at about z ~ 1 that were fainter than expected. If they were standard candles then this would mean that they were further away than expected and therefore the universe must have been accelerating rather than decelerating.

    This requires a special form of energy with negative pressure, called Dark Energy. (May I recommend Scholarpedia - which is peer reviewed unlike Wikipedia - though its articles are slow to come on line as they are being written and reviewed carefully).

    Beyond z> 1.5 in the earlier universe they become brighter than expected again, meaning there the expansion was decelerating as 'normal'.

    Thus we can observe the early epoch (z > 1.5) where the expansion was decelerating as 'normal' and the recent epoch (z < 1.5) where DE has kicked in. Note: In your post you have got your < & > signs the wrong way round)

    Of course we can ask questions about how 'standard' the SNe Ia candle actually is over cosmological time and also which cosmological models fit the data and it is the standard model that fits all the known data best.

    Garth
     
    Last edited: Nov 4, 2007
  4. Nov 3, 2007 #3

    marcus

    User Avatar
    Science Advisor
    Gold Member
    2015 Award
    Dearly Missed

    For some years I've been hearing Alain Blanchard voice his doubts. But my impression is that since around 2005 he is talking about it less and less often. I think he is somewhat a lone isolated figure now. He never had an iron-clad case----his objections and alternative ideas were always iffy---and he doesnt seem to have convinced the rest of the community.

    This doesnt PROVE anything. Since 2005 as we hear less and less it seems less and less likely that he was on to something real. You never get ultimate certainty.

    Your quote may be referring to some other discrepancies, including some very recent observations. The thing is, there are ALWAYS new observations and possible discrepancies are remarked----and they are usually minor and usually get explained away, or they cause a minor modification of some part of the picture.

    In the case of Blanchard, even if his arguments stood up and people were taking him seriously it would JUST CHANGE SOME NUMBERS. His argument would not make a qualitative difference to there having been a hot dense state of the universe at the beginning of expansion. If i remember correctly, he was still using the usual Friedmann model of an expanding universe, it just needed different numbers to work.

    I don't know what bugs some people about expansion cosmology. It is beginning to seem pretty funny to me. Have you any idea why it seems to get their goat?
     
  5. Nov 3, 2007 #4
    Thank you Garth for clearing this up for me. I am fairly new to the wonderful world of physics, and I am interested to learn more. Your assumption that I am not a YEC is correct. Also, thank you for referring me to Scholarpedia. One last thing: the section of your post that was about Dark Energy during the early epoch and the recent epoch being reversed is not of my doing - it was actually on the site itself! When will these creationists learn to stop misquoting?
     
  6. Nov 3, 2007 #5

    EL

    User Avatar
    Science Advisor

    When will they learn anything?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: A Problem with the Big Bang
  1. The Big Bang (Replies: 17)

  2. The Big Bang (Replies: 2)

  3. The Big Bang (Replies: 38)

Loading...