Inquiries into 1997ff
Posted Nov24-08 at 08:08 PM by WCOLtd
I was watching a video on youtube Richard Feynman's "Take the world from another point of view" - the third video - 5:20 - 7:13
they were talking arbitrarily about some problem with a quasar, that observations did not meet physical requirements, stating; "If there were any cause for a redshift as big as that other than a recession it would be alright but under the present physical law there doesn't seem to be a place for such a redshift" But we can't get it to fit right". That really made me jump out of my chair, immediately I thought of my suspicion that "redshift is not solely the result of a recession velocity". In "Evidence for Fading Stars?"
I'd really like to know what they were referring to. Yet even though I didn't know what it was (its probably been resolved by now) it inspired me to find out if my presumption - (that the redshift is not the necessarily the result of a recession velocity) - is correct or incorrect.
I thought for a bit about how I would prove this - how would I best demonstrate this is the case?
total luminosity/observed luminosity and angular size are both indicators of distance - both are inversely related to the proper distance between the observer and the observed body.
With redshift, we can supposedly infer the recession velocity. Since recession velocity is distance/time both luminosity and angular size will decrease with time (because the observed body will be further away).
So then I looked for cosmological candles with the highest luminosity, and the only one that really interested me was 1997ff located an astonishing 11.3 billion light years away with a redshift of 1.7.
I realized then that 11.3 billion years is maybe too far away, because it's angular size would be so small, 1/ of the nights sky and I worried that even with the best instruments, we would not be able to infer recession velocity independent of redshift, unless we had some impractical exposure of time (like say 10,000 years) even with the most sensitive of instruments.
So I cant keep going this way, I have to think of another way.
I e-mailed an astrophysicist about this problem and he was kind enough to respond
He first tried to clarify his understanding
"If I'm understanding your question correctly, you are pointing out that the angular-diameter distance turns over at redshift ~ 1.5. You ask whether this could be confirmed correctly.
*{The only thing is I don't understand what he means by "turns over" so I think I am going to ask him what he means by this}
I am working on a better e-mail right now
He first addressed an issue with the question I was already aware of. My particular method I suggested was to measure the angular size of the type 1a supernova over time - however the diameter of a supernovae is always increasing over time. I believe two things 1) it will probably not be an issue as all I want is an estimate - a number I can start working off of and 2) the size should increase at a particular rate which is calculable and therefore can be compensated for even if I was worried about it.
He then suggested that I should be concerned more with the luminosity - which is subject to the same issue - because that too changes with as with all type 1a supernovae, but that the rate at which it changes is entirely calculable - and therefore should be able to compensated for.
I didn't address these things in the e-mail because I wanted the message to be brief so that he could understand what it was I wanted.
What I want is a way to measure recession velocity independent from redshift.
they were talking arbitrarily about some problem with a quasar, that observations did not meet physical requirements, stating; "If there were any cause for a redshift as big as that other than a recession it would be alright but under the present physical law there doesn't seem to be a place for such a redshift" But we can't get it to fit right". That really made me jump out of my chair, immediately I thought of my suspicion that "redshift is not solely the result of a recession velocity". In "Evidence for Fading Stars?"
I'd really like to know what they were referring to. Yet even though I didn't know what it was (its probably been resolved by now) it inspired me to find out if my presumption - (that the redshift is not the necessarily the result of a recession velocity) - is correct or incorrect.
I thought for a bit about how I would prove this - how would I best demonstrate this is the case?
total luminosity/observed luminosity and angular size are both indicators of distance - both are inversely related to the proper distance between the observer and the observed body.
With redshift, we can supposedly infer the recession velocity. Since recession velocity is distance/time both luminosity and angular size will decrease with time (because the observed body will be further away).
So then I looked for cosmological candles with the highest luminosity, and the only one that really interested me was 1997ff located an astonishing 11.3 billion light years away with a redshift of 1.7.
I realized then that 11.3 billion years is maybe too far away, because it's angular size would be so small, 1/ of the nights sky and I worried that even with the best instruments, we would not be able to infer recession velocity independent of redshift, unless we had some impractical exposure of time (like say 10,000 years) even with the most sensitive of instruments.
So I cant keep going this way, I have to think of another way.
I e-mailed an astrophysicist about this problem and he was kind enough to respond
He first tried to clarify his understanding
"If I'm understanding your question correctly, you are pointing out that the angular-diameter distance turns over at redshift ~ 1.5. You ask whether this could be confirmed correctly.
*{The only thing is I don't understand what he means by "turns over" so I think I am going to ask him what he means by this}
I am working on a better e-mail right now
He first addressed an issue with the question I was already aware of. My particular method I suggested was to measure the angular size of the type 1a supernova over time - however the diameter of a supernovae is always increasing over time. I believe two things 1) it will probably not be an issue as all I want is an estimate - a number I can start working off of and 2) the size should increase at a particular rate which is calculable and therefore can be compensated for even if I was worried about it.
He then suggested that I should be concerned more with the luminosity - which is subject to the same issue - because that too changes with as with all type 1a supernovae, but that the rate at which it changes is entirely calculable - and therefore should be able to compensated for.
I didn't address these things in the e-mail because I wanted the message to be brief so that he could understand what it was I wanted.
What I want is a way to measure recession velocity independent from redshift.
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