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Thread: Super-supernovae spell trouble for dark energy

  1. #1 Super-supernovae spell trouble for dark energy 
    Forum Radioactive Isotope sculptor's Avatar
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    Super-supernovae spell trouble for dark energy :

    ...type-1a supernovae. We think we know what makes these stellar bombs tick and a lot rides on us knowing it. Above all, they detonate with a similar brightness, a fact that allows us to calibrate distance in the universe. Observations of type-1a supernovae led 15 years ago to one of the landmark discoveries of modern cosmology: that the expansion of the universe is accelerating, fuelled by a shadowy agent since dubbed dark energy.

    Except if what Howell was saying was right, things weren't that simple. He and his colleagues had seen
    and, there, I was paywalled out.
    (damn)

    Has anyone got more information on the postulations hinted at in the intro-teaser?


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  3. #2  
    Forum Ph.D.
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    You should give a reference as to where the quote is from.


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    AI's Have More Fun Bad Robot's Avatar
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    Quote Originally Posted by mathman View Post
    You should give a reference as to where the quote is from.
    The following link might help a little. It appears that the provocative title is aimed at getting more people to subscribe to New Scientist.

    CR4 - Blog Entry: Super-Supernovae Spell Trouble for Dark Energy
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  5. #4  
    Anti-Crank AlexG's Avatar
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    Howell, on his web site, calls the New Scientist article 'just weird'.

    https://sites.google.com/site/dahowell/

    J
    ust another case of bad reporting.
    Its the way nature is!
    If you dont like it, go somewhere else....
    To another universe, where the rules are simpler
    Philosophically more pleasing, more psychologically easy
    Prof Richard Feynman (1979) .....

    Das ist nicht nur nicht richtig, es ist nicht einmal falsch!"
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  6. #5  
    Forum Radioactive Isotope sculptor's Avatar
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    Quote Originally Posted by mathman View Post
    You should give a reference as to where the quote is from.
    oops forgot
    Sign in to read: Super-supernovae spell trouble for dark energy - space - 01 August 2013 - New Scientist

    ...................
    I suspect that badrobot nailed it.

    ..............thanks for the links guys
    great fun
    Last edited by sculptor; August 4th, 2013 at 09:45 PM.
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  7. #6  
    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by Bad Robot View Post
    The following link might help a little. It appears that the provocative title is aimed at getting more people to subscribe to New Scientist.
    No surprises there. They are very fond of tabloid headlines like "Darwin|Einstein was wrong", "Scientists baffled by quantum physics" and so on.
    Without wishing to overstate my case, everything in the observable universe definitely has its origins in Northamptonshire -- Alan Moore
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    double post
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    sculptor,

    Super-supernovae spell trouble for dark energy :

    ...type-1a supernovae. We think we know what makes these stellar bombs tick – and a lot rides on us knowing it. Above all, they detonate with a similar brightness, a fact that allows us to calibrate distance in the universe. Observations of type-1a supernovae led 15 years ago to one of the landmark discoveries of modern cosmology: that the expansion of the universe is accelerating, fuelled by a shadowy agent since dubbed dark energy.

    Except if what Howell was saying was right, things weren't that simple. He and his colleagues had seen and, there, I was paywalled out.
    (damn)

    Has anyone got more information on the postulations hinted at in the intro-teaser?
    After reading a summary of the above article in New Scientist, the point of the article was that type 1a supernova can accordingly occur from multiple sources so how can the data be trusted to be a consistent standard candle. This accordingly might bring type 1a supernova data and dark energy into question.

    It has long been proposed that type 1a supernova are caused by exploding white dwarf stars. The first such hypothesis involved a binary star system, whereby a white dwarf star robs matter from a red-giant neighbor, causing the white dwarf star to eventually explode in a giant fusion explosion called carbon detonation. In the last decade an alternative model was proposed whereby two white dwarf stars merge whereby only one will explode via carbon detonation. More recently there is supposed evidence that both models could be valid and that some type 1a explosions could be caused by either mechanism.

    The subject article, based upon observation of a recent supernova, discusses a third mechanism where a nova event in a binary star system sends ejected nova matter into a companion binary white dwarf star. The white dwarf accordingly exploded within millennia thereafter, upon acquiring the required theoretical critical mass. Its outward expanding waves from the explosion could be traced going through a companion star as well as what appeared to be the ejecta from a prior nova explosion of the companion star in the not too distant past. So this is not just theory, but theory with strong evidential support.

    The question being asked in the article was that with so many possible causal mechanisms the outcomes could also be different, therefore could they still come to a valid conclusions concerning type 1a supernova as being standard candles? Could they validly conclude the existence of dark energy based upon these possibly variant standard-candle events?

    I think the error in this argument is that in all proposed hypothesis/ theory type 1a supernova result from the explosion of type 1a supernova stars. It may not matter at all how a white dwarf star acquires its critical mass to explode. White dwarf stars are believed to be the remnants of very old main sequence stars like the sun. White dwarfs stars, according to theory and observation, range in size from .17 to 1.33 solar masses, the majority lie within the range of .5 to .7 solar masses. The critical mass might involve similar sized white dwarfs to produce type 1a supernova, standard candle-like explosions.

    White dwarf - Wikipedia, the free encyclopedia

    I have read (and written) what I consider to be "more worthy" criticisms of the dark energy hypothesis than this one. Although I have enjoyed a number of New Scientists' past speculative articles, I think this speculation is not one of their better ones.
    Last edited by forrest noble; August 5th, 2013 at 11:11 PM.
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    AI's Have More Fun Bad Robot's Avatar
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    Quote Originally Posted by forrest noble View Post
    I think the error in this argument is that in all proposed hypothesis/ theory type 1a supernova result from the explosion of type 1a supernova stars. It may not matter at all how a white dwarf star acquires its critical mass to explode. White dwarf stars are believed to be the remnants of very old main sequence stars like the sun. White dwarfs stars, according to theory and observation, range in size from .17 to 1.33 solar masses, the majority lie within the range of .5 to .7 solar masses. The critical mass might involve similar sized white dwarfs to produce type 1a supernova, standard candle-like explosions.
    With regard to this point, I don't think the starting size of the white dwarf would make any difference to the critical mass needed to produce a type 1A. The only thing I can think of about this is that a smaller white dwarf star would just take longer to reach the required critical mass, but the type 1A supernova would still only happen when virtually the same critical mass was reached in every case. In the case where two large white dwarfs merge the critical mass might be exceeded by quite a bit and it's possible this could produce a brighter type 1A.
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  11. #10  
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    Quote Originally Posted by Bad Robot View Post
    Quote Originally Posted by forrest noble View Post
    I think the error in this argument is that in all proposed hypothesis/ theory type 1a supernova result from the explosion of type 1a supernova stars. It may not matter at all how a white dwarf star acquires its critical mass to explode. White dwarf stars are believed to be the remnants of very old main sequence stars like the sun. White dwarfs stars, according to theory and observation, range in size from .17 to 1.33 solar masses, the majority lie within the range of .5 to .7 solar masses. The critical mass might involve similar sized white dwarfs to produce type 1a supernova, standard candle-like explosions.
    With regard to this point, I don't think the starting size of the white dwarf would make any difference to the critical mass needed to produce a type 1A. The only thing I can think of about this is that a smaller white dwarf star would just take longer to reach the required critical mass, but the type 1A supernova would still only happen when virtually the same critical mass was reached in every case. In the case where two large white dwarfs merge the critical mass might be exceeded by quite a bit and it's possible this could produce a brighter type 1A.
    A smaller white dwarf's explosion might produce a different kind of supernova if it can supernova at all. Type 1a supernova are called carbon detonations (fusion explosions). If two white dwarfs merge, I think only one of the two is supposed to explode according to theory. The other white dwarf star of a pair, I think is supposed to simply blown apart from the explosion and be little involved in the carbon detonation process. If a brighter supernova results, the resultant supernova may not fit the profile of a type 1a supernova.

    It appears that the the related theories are still evolving.
    Last edited by forrest noble; August 6th, 2013 at 10:16 PM.
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