Author Topic: Farthest SUPERNOVA Ever Discoverd  (Read 2000 times)


Budgieye

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Re: Farthest SUPERNOVA Ever Discoverd
« Reply #1 on: November 02, 2012, 06:49:14 am »
Hmmm... z= 2.05 and 3.90
Amazing that we can see them 3/4 of the way across the universe. :o

WR

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Re: Farthest SUPERNOVA Ever Discoverd
« Reply #2 on: November 03, 2012, 10:03:57 pm »
Hello

We need many more of the far away ones.
Especially the ones of type 1a !

IMHO its not save yet that we live in an accelerated universe.
Why ?
That model is based on the axiom that the used distances
are 100% well known. But they aren't ! The actually used
distance guesses involve several steps to get that far away.
Every of these steps has an uncertainty of a few to more
than 10%. But the differences between some of these models
make just a difference of 0.1 mag = 10% in brightness.
An other source of doubt is IMHO e.g. the two guessed galac-
tical interstellar and interstellar extinction that can easily make
up a difference of more than 0.1 mag in the observed brightness.

It would not be the first time that even nobel price winners
were in error.

Clear skies
Wolfgang

graham d

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Re: Farthest SUPERNOVA Ever Discoverd
« Reply #3 on: November 05, 2012, 12:24:07 am »
I've not managed to get hold of a copy of the online paper in Nature. From the media's reports of the authors comments the emphasis is about pair production instabilty processes in extremely massive low metallicity stars. The main point appears to be that these ultra bright supernovae are produced at a rate >10 fold than their counterparts in the local universe. The z data come from their host galaxy spectra. They need many more of them before they can be used as standard candles , or calibrated ones. We may need many more high z type 1a but we will not get them without new deep field, ulta and extraultra surveys.

Whether you accept the accelerated expansion or not or are ideally sceptical of it, indeed it's scientific to retain doubt, the dark energy or cosmological constant "measurements" allows for the 7%-15% errors inherent in the two numbers that the cosmologists most worry about. Panek's book "The 4% Universe", Oneworld, 2011 details the rivalry, animosity and the Darwinian infighting amongst rival high z supernova teams in their race to promote the type 1a standard candle. The accelerated expansion interpretation appears to be the only thing they agreed upon.

There's no real mention as to what constitutes ordinary universal expansion in the book. Actually by the time you get back to this high z distance space was expanding at greater than the speed of light from general relativity considerations of a truly empty space. At z=2 the universe size factor was 3 and the average density of matter is 33 greater than our time in the local universe. The Hubble sphere is at 13.7 billion years but what was there then is now much further away ca. 3 fold at a more distant particle horizon. The Hubble constant varies with time and it's the gravitating effect of matter in space that is slowing down the expansion, or that second number the cosmologists need to know; an effect noted by the high z teams, in that the type 1as were brighter by ca. 2 fold than expected. In the local universe out at z~0.5 the supernovae appear dimmer by ca. 25% or redisfted whereas amazingly the high z>2 ones were blueshifted! The universe according to received wisdom? passed from a decelerating phase to an accelerating more recent phase. Wolfgang is questioning the reliability of the data. I like to think the data is basically sound and that a different interpretation is warranted. Everyone accepts charged lepton pair production occurs in the Big Bang going from thermodynamically a hot to cold mode. Conceptually, the baryons or let us simplify and say that there's no hydrogen or atoms around at this BB epoch or the first second. For a star you tend to reverse the process and make the tacit assumption that for first light one needs stars full of H and He but no metalics and treat the process as going from a cold to hot mode that never reaches equilibrium, because the pair production process leads to a runaway effect that generates more energy than can be contained by a gravitational field; a kind of mini BB effect. First light is indeed a misnomer for the particle physicists since the pair production process is inherent to the vacuum. There are always particles there, inherent in the nature of space and they neither stretch nor accelerate to superluminal velocities. Now I don't intend to beat the drum here, not while we are all glued to the US TV suffering from incessant election fever addiction.
« Last Edit: November 05, 2012, 12:30:30 am by graham d »

Blackprojects

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Re: Farthest SUPERNOVA Ever Discoverd
« Reply #4 on: November 06, 2012, 03:01:39 am »

graham d

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Re: Farthest SUPERNOVA Ever Discoverd
« Reply #5 on: November 06, 2012, 10:30:06 pm »
That's small beer.
http://www.science20.com/greatest_science_mysteries/multiverse-96001

Alan Guth finally commits himself to the numerosity of the universei as aleph zero ,which you may know is a transinfinity. 10500 possible universes pales into insignificance by comparison. Even

                 500           
          500
10500

is an insignificant leap of the imagination hungry for free lunches.