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Ewol
21st September 2011 - 03:53 PM
After finding some information on redshift I would like to put forward the following.
As distance increases so redshift increases but you are looking further back in time, but if you look at the timeline from past to present rather than distance from here to there then redshift decreases, the greatest redshift being furthest back in time.
Does this show that in fact the expansion of the universe is slowing rather than accelerating.
Ewol
22nd September 2011 - 09:03 AM
No one telling me I am wrong again!
The figures I have (Times are years from BB)
CMB 380000 Redshift 1100
First stars 100m Rs 20 Est
Early galaxy UDFj 39546284 480m Rs 10.3 Est
Gamma ray burst GRB 090429B 520m Rs 9.4
Galaxy UDFy 38135539 600m Rs 8.6
G ray burst GRB 090423 630m Rs 8.2
Quasar ULAS J1120+0641 770m Rs 7.1
Chandra Deep Field south X-Ray image 800m Rs 6.5
I have no figures for anything closer in time.
If these were plotted on a graph using time and redshift it looks to me that it would have a similar shape to a time dilation graph. A big drop from CMB to 1st stars then a leveling off but still reducing.
The figures show a definite reduction in redshift the closer you get to the present.
Kino
22nd September 2011 - 02:15 PM
QUOTE (Ewol+Sep 22 2011, 09:03 AM)
No one telling me I am wrong again!

Probably because you never listen to the answers.

Before you declare victory, why don't you work out (or look up) what the relationship between redshift and distance is assuming that the conventional explanation is correct?
Ewol
23rd September 2011 - 05:14 PM
As far as I can find out redshift depends on distance the greater the distance the greater the redshift.
But as I pointed out the greater the distance the further back in time so the greater the redshift the closer to the beginning of the universe. In other words it shows a greater rate of expansion the further back in time so expansion must be slowing down not speeding up.
I have also found out that at least some redshift seems to be quantized, it appears to be found in discrete bands, this also appears to show that it is not linked to universal expansion.
AlexG
23rd September 2011 - 07:02 PM
QUOTE
In other words it shows a greater rate of expansion the further back in time so expansion must be slowing down not speeding up.


No, it shows that the more time that's passed, the more time there's been for expansion to speed up.

If you look at an accelerating car at ten seconds, and then at 60 seconds, the car will be going faster at 60 seconds. That does not imply that the car was going even faster at ten seconds.
Ewol
25th September 2011 - 04:43 PM
Already thought about the car scenario but it does not work in this case as the car is going into the future, the highest redshift is from the earliest part of the universe so back in time, you have no idea what is happening at those distances now as the light that leaves there today will not arrive for us to see until after the earth is gone so the light you are looking at is 13 billion years old and left before the sun was born.
To me it shows a high expansion rate early on that has been decreasing ever since. You do not mention anything about the quantization either which also shows that at least some redshift is nothing to do with universal expansion.
To be honest space expanding sounds a ridiculous idea anyway
Kino
25th September 2011 - 05:16 PM
You didn't take my advice to look up the predicted form of the redshift, I presume. Assuming a constant expansion rate, the observed redshift at a distance d is z=H0.d/(t-d/c) in a Newtonian universe, where t is the age of the universe in seconds and H0=H/c.t and H is Hubble's constant. The functional form of that expression, if you want to plot it, is y=x/(1-x) in the range x=0 to x=1. GR modifies this somewhat (eliminating the singularity for one) but has a similar form. The point is that the Hubble model leads to exactly the behaviour you are observing. A decelerating universe would look rather different.

Before jumping to conclusions about quantisation, I would look for error bars. A redshift of 1050+/-100 will be posted as 1100, as will 1149+/-100. Edit: putting it crudely.
AlexG
25th September 2011 - 06:20 PM
QUOTE (Ewol+Sep 25 2011, 11:43 AM)
Already thought about the car scenario but it does not work in this case as the car is going into the future, the highest redshift is from the earliest part of the universe so back in time, you have no idea what is happening at those distances now as the light that leaves there today will not arrive for us to see until after the earth is gone so the light you are looking at is 13 billion years old and left before the sun was born.
To me it shows a high expansion rate early on that has been decreasing ever since. You do not mention anything about the quantization either which also shows that at least some redshift is nothing to do with universal expansion.

The farthest stars are also going into the future. The highest redshift is from the farthest distances. The further something is from us, the longer it has been receeding, which means the longer the space between us has been expanding.

QUOTE
To be honest space expanding sounds a ridiculous idea anyway
To be honest, your opinion on the subject is worthless.
Ewol
26th September 2011 - 11:44 AM
What I am trying to say is that if the early universe was expanding rapidly then the redshift in the light from that period would remain high even without a currently expanding universe because the redshift would be built in for want of a better phrase. To compare expansion rates between then and now you would need to see the redshift from the same object as transmitted today but that is not going to happen as there is 13 billion years inbetween.
If the universe was collapsing now we would not see it because that information is behind or following the light we actually see.
Your information is based on data up to 13 billion years old.
I am not disputing the maths behind our interpretation of redshift just the interpretation of the results.
Kino
26th September 2011 - 03:41 PM
QUOTE (Ewol+Sep 26 2011, 11:44 AM)
What I am trying to say is that if the early universe was expanding rapidly then the redshift in the light from that period would remain high even without a currently expanding universe because the redshift would be built in for want of a better phrase. To compare expansion rates between then and now you would need to see the redshift from the same object as transmitted today but that is not going to happen as there is 13 billion years inbetween.
If the universe was collapsing now we would not see it because that information is behind or following the light we actually see.
Your information is based on data up to 13 billion years old.
I am not disputing the maths behind our interpretation of redshift just the interpretation of the results.

No. The correct interpretation is based on data spanning all of the 13bn year history of the visible universe and a strong theoretical underpinning in General Relativity. Your interpretation requires you to ignore the most recent 10bn years or so and has no relation to any known theory.

If the universe were undergoing the kind of strong deceleration that you are talking about, nearby galaxies would have lower redshifts than they do because they are visible in a more recent epoch when expansion would have slowed. Really, Ewol, all of the evidence is consistent with a slightly accelerating expansion. The curves for other forms do not fit; if you adjust them to fit data around 10-13bn years ago they are out of place for all of the last 10bn years.

This would be obvious to you if you went and studied some basic maths - why are you so resistant to the idea? You wouldn't have to trust that I'm not trying to baffle you with bullshit on things like this, and you'd be able to work out on your own if your ideas were plausible or not.
Ewol
27th September 2011 - 03:46 PM
Unfortunately it is very difficult trying to find figures for redshift, the ones I quoted are actually the only ones I have found which is why I have not included the last 10b years, I have not ignored it just have no knowledge of it. I do not know the variation in redshift values say between the closest object and the furthest just that the furthest are around 20 as quoted. Perhaps you could enlighten me with some of the values of closer objects say with 500 light years difference which would give 20 values for the last 10b years. As far as I can make out the closer objects have redshifts of less than 1.
As I said though the values for the 1st 3b years seem to show rapid deceleration i.e from 1100 cmb to 20 at first stars, followed by reducing deceleration surely if the universe was expanding then the redshift should be higher for closer objects. Algebraic equations are all very well if you know what numbers to use, the equation you gave is fine as long as you know which letters to replace with which numbers, put simply y=x+1 is meaningless without a value for either x or y.
Ewol
9th November 2011 - 09:33 AM
Have since found out a bit more.
It would seem the closer you get to us the lower the redshift.
So I will accept that redshift decreasing over time, from the past to now, and space = a speeding up of the universe, the same way a car accelerating away into the future will give an increasing redshift.
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