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Accelerating universe? Not so fast

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Uwe

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http://www.sciencedaily.com/releases/2015/04/150411091607.htm
www.sciencedaily.com said:
Astronomers have found that the type of supernovae commonly used to measure distances in the universe fall into distinct populations not recognized before. The findings have implications for our understanding of how fast the universe has been expanding since the Big Bang.
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I am a "cosmic inflation" skeptic, flame me as you will. This finding supports one of my primary quibbles with that hypothesis: the use of the type 1a supernova in measurements of cosmic distance. That it also has implications against dark energy (or matter) is just icing on the cake.
 
How fast the universe is expending is in question there though. The paper does not give any numbers so it could be anything from a minor revision to no acceleration at all.

Yes this does question what happened in the early universe, just what is happening now.
 
rjh01 said:
How fast the universe is expending is in question there though. The paper does not give any numbers so it could be anything from a minor revision to no acceleration at all.

Yes this does question what happened in the early universe, just what is happening now.
Click to expand...

You meant to say "Yes this not does question what happened in the early universe"?
 
Jimmy Higgins said:
barbos said:
Cosmic inflation is not in any way in question here.
Click to expand...
What a load. If the universe was constantly accelerating (somewhat of a pun intended), it'd have gotten a ticket by now.
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That's why some physicists question the model of an initial inflationary period. It would have required the universe to greatly exceed the speed limit of c. The universe would have been pulled over and ticked for such a blatant speed violation.
 
skepticalbip said:
Jimmy Higgins said:
What a load. If the universe was constantly accelerating (somewhat of a pun intended), it'd have gotten a ticket by now.
Click to expand...
That's why some physicists question the model of an initial inflationary period. It would have required the universe to greatly exceed the speed limit of c. The universe would have been pulled over and ticked for such a blatant speed violation.
Click to expand...
And most likely shot up by the cops.
 
barbos said:
rjh01 said:
How fast the universe is expending is in question there though. The paper does not give any numbers so it could be anything from a minor revision to no acceleration at all.

Yes this does question what happened in the early universe, just what is happening now.
Click to expand...

You meant to say "Yes this not does question what happened in the early universe"?
Click to expand...

Yes, somehow that word got lost somewhere between the brain and computer. Sorry about that.
 
this article doesn't say what the technical names of the different supernovae are.

I am very confused by it.

This is the paper:
http://arxiv.org/pdf/1408.1706v1.pdf

too much to read now, and difficult to have anything close to the background needed.

I don't understand what NUV-red and NUV-blue means. Also, if the amounts of these types have switched is that because of something about the universe as it has gotten older, like metallicity of stars changing?

How about assuming that NUV-red and blue ratios are the same then as now, can parameters be changed to make a NUV-red a NUV-blue?

I tried reading it and metallicity is mentioned. This is very dense stuff, and also has tons of unknowns. I don't think this will overturn anything.

What other standard candles are there besides type 1a supernovae at such long distances?

From wiki:

http://en.wikipedia.org/wiki/Cosmic_distance_ladder#Standard_candles
A significant issue with standard candles is the recurring question of how standard they are. For example, all observations seem to indicate that Type Ia supernovae that are of known distance have the same brightness (corrected by the shape of the light curve). The basis for this closeness in brightness is discussed below; however, the possibility exists that the distant Type Ia supernovae have different properties than nearby Type Ia supernovae. The use of Type Ia supernovae is crucial in determining the correct cosmological model. If indeed the properties of Type Ia supernovae are different at large distances, i.e. if the extrapolation of their calibration to arbitrary distances is not valid, ignoring this variation can dangerously bias the reconstruction of the cosmological parameters, in particular the reconstruction of the matter density parameter.[9]
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I did not look too carefully but all it seems they got data in UV spectrum for the first time and it does not look like what they expected. In other words UV data is not consistent with visible light data. They interpret it as supernovas used as standard candles are not that standard and actually systematically change with time. I personally think it's 50-50.
I would not be surprised if they soon find an explanation for inconsistencies.


And again this does not affect cosmic inflation in any way. Cosmic inflation ended when universe was 1.e-32 seconds old, long before anything resembling stars were formed.
 
barbos said:
And again this does not affect cosmic inflation in any way. Cosmic inflation ended when universe was 1.e-32 seconds old, long before anything resembling stars were formed.
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I thought he was talking about accelerating expansion of spacetime (not the initial inflationary period)?
 
Kharakov said:
barbos said:
And again this does not affect cosmic inflation in any way. Cosmic inflation ended when universe was 1.e-32 seconds old, long before anything resembling stars were formed.
Click to expand...
I thought he was talking about accelerating expansion of spacetime (not the initial inflationary period)?
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Well, he used "cosmic inflation" to refer to whatever he was talking about.
 
Kharakov said:
C_Mucius_Scaevola said:
It's not, though. It's beige.
http://www.newscientist.com/article/dn2013-the-universe-is-not-turquoise--its-beige.html
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Ehh... that is the average color of light in the universe. Space is as black as my heart.
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Oh come on. We're talking about relative distances/probabilities between detectable stuff. Space is defined by a criteria of relative lack of that stuff its not defined by not by that stuff's absence.

This whole thing tries to relate to that which it doesn't. What were the conditions when gravity broke free from the other forms of energy back in the day? Why wold anyone suggest the speed limit was set when the forces were unified or before that all broke apart? Back to Hubble?
 
barbos said:
...And again this does not affect cosmic inflation in any way. Cosmic inflation ended when universe was 1.e-32 seconds old, long before anything resembling stars were formed.
Click to expand...
I believe I understand your point. Also, my point about inflation does make several leaps of logic between the subject results and Inflationary models, apologies for that. A ibt of vaguebooking really now that i re-read my OP.

The ages and distances of distant objects is at the core of Big Bang cosmology, and therefore particularly of Inflation. One of my least favorite scientific assumptions, that has until now been taken as gospel in much of the lay literature, is that the 1a supernovae are iron-clad distance indicators. Basically I'm excited to see: a. if the results holds up (unscientifically, I am rooting for that), b. how the theorists will have to adjust the distance scales, and by consequence the "age of the universe," and c. what sort of new adjustment will need to be made to Inflation theory to maintain its predictive power in light of this new data.
 
fromderinside said:
Kharakov said:
Ehh... that is the average color of light in the universe. Space is as black as my heart.
Click to expand...

Oh come on. We're talking about relative distances/probabilities between detectable stuff. Space is defined by a criteria of relative lack of that stuff its not defined by not by that stuff's absence.
Click to expand...
Space does not emit light according to what I've read (although I acknowledge my, and possibly most other non-space being's ignorance in this matter).

It emits dark, by expanding faster than light. :cheeky:
 
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