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A Laboratory Experiment for Astronomers ("Look-Back")



 
 
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  #1  
Old October 30th 14, 11:03 PM posted to sci.astro.research
Eric Flesch
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Default A Laboratory Experiment for Astronomers ("Look-Back")

On Mon, 15 Sep 14 20:17:26 GMT, Phillip Helbig wrote:
writes:
As a gedankenexperiment, let's look at two mathematical spheres, one
larger than the other. The larger sphere has a lower SA-to-V ratio
than the other. This is an intrinsic difference. Now place each
sphere into its own empty universe. The spheres haven't changed, one
still has a different intrinsic nature to the other, but we have no
metric to distinguish them. So I suggest we need a universal
parameter of "scale" to account for this -- which would be a
characteristic or dimension of the space-time manifold.


Interesting concept. Julian Barbour has also been investigating scale
recently. Check up on his recent stuff.


Thanks for that reference, Phil, I've been reading up on his very
interesting work on "scale". However, he seems to view "scale" as
operating only on the xyz dimensions (although I haven't read deeply
enough to be sure) whereas I'd say it operates on the space-time
manifold so that the rate of time flow is equally impacted. And that
brings me to a concept that can be experimentally tested.

As I've posted on other occasions, a registering photon is a perfect
archive of itself at the time of emission (although Doppler effects
apply of course). Its state at the time of emission includes the
universal parameters operating at the time of its emission. So a z=1
photon should present those parameters, available for us to decode.
We currently interpret redshift as Doppler-like due to an expanding
universe, etc etc.

Julian Barbour points out that if scale is relative as it should be
(and he has published multiple papers which generalize GR into a
scale-relative construct from which GR can be derived in intuitive
ways) then we shouldn't be able to see the universe expand, because
scale would increase with it and all would look unchanging to us.
This is because he hasn't taken "Look-Back" into account, that e.g.
z=1 photons show us the older conditions.

If Barbour's well-published "relative scale" is operative, then z=1
photons were emitted under an earlier "scale" state, and it is
possible that they are travelling at speeds slower than c -- such as
c/2 for z=1 photons. All of our measurements of c have been done on
local photons. Does anyone really know how fast the z=1 photons are
travelling -- if they are travelling at c/2, then that fully explains
the redshift and kills the "expanding universe" stone cold dead.

So here is a laboratory experiment for intrepid astronomers -- find
out how fast those z=1 photons are travelling! How can it be done?
Do we have any way of measuring the speed of a photon, or can we only
measure time from emission to registration? As John Wheeler states,
"we have no right to speak of the attributes of a photon before it has
registered", so doesn't that include its speed?

Who can design such a laboratory experiment?

cheers,
Eric Flesch
  #2  
Old October 31st 14, 12:29 PM posted to sci.astro.research
jacob navia[_5_]
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Default A Laboratory Experiment for Astronomers ("Look-Back")

Le 30/10/2014 23:03, Eric Flesch a écrit :
Who can design such a laboratory experiment?


I do not know really but if a nearby star and a quasar are very near in
the sky, and the moon occultates them both.

After the moon passes, if the speed of the quasars photons is c/2 we
should start seeing the quasar a whooping 0.5 seconds later as the
nearby star isn't it?

(Assuming distance earth moon 300 000 Km and c 300 000 Km)

This doesn't seem like VERY difficult to do.

P.S. I want a percentage of the Nobel Prize money please

:-)
  #3  
Old October 31st 14, 12:30 PM posted to sci.astro.research
Phillip Helbig---undress to reply
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Default A Laboratory Experiment for Astronomers ("Look-Back")

In article , Eric Flesch
writes:

As I've posted on other occasions, a registering photon is a perfect
archive of itself at the time of emission (although Doppler effects
apply of course).


This seems to be an assumption. If the photon is redshifted (via
whatever mechanism), then it is not clear that it is otherwise a perfect
record.

We currently interpret redshift as Doppler-like due to an expanding
universe, etc etc.


Yes, but that is not the only evidence for an expanding universe.

possible that they are travelling at speeds slower than c -- such as
c/2 for z=1 photons. All of our measurements of c have been done on
local photons. Does anyone really know how fast the z=1 photons are
travelling -- if they are travelling at c/2, then that fully explains
the redshift and kills the "expanding universe" stone cold dead.


Even assuming that that would be the case, i.e. this would rule out an
expaning universe, you still have to explain other consequences of the
expanding universe, such as the relative light-element abundances.
These numbers depend on the idea of the hot big bang, which implies
expansion.

So here is a laboratory experiment for intrepid astronomers -- find
out how fast those z=1 photons are travelling! How can it be done?
Do we have any way of measuring the speed of a photon, or can we only
measure time from emission to registration? As John Wheeler states,
"we have no right to speak of the attributes of a photon before it has
registered", so doesn't that include its speed?


It is relatively easy to measure the speed of light in the laboratory.
I see no reason that couldn't be done with extragalactic photons.

Who can design such a laboratory experiment?


Is it necessary? The ones we already have had for centuries should
work.

What about radio interferometry? It is routinely used to observe
objects at cosmological distances and I'm sure that the speed of light
enters into the equations somewhere. With VLBI, one has to correct for
continental drift and the fact that the Earth slows down in the northern
spring because there are more trees in the northern hemisphere, so it
would surprise me if a different photon speed had no effect.
  #4  
Old October 31st 14, 12:32 PM posted to sci.astro.research
Harri Tavaila[_4_]
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Default A Laboratory Experiment for Astronomers ("Look-Back")

31.10.2014 0:03, Eric Flesch kirjoitti:
Who can design such a laboratory experiment?


A variation of speed in the scale suggested (c/2) should be evident in
aberration, thus no special experiment is required.

H Tavaila

[Mod. note: quoted text trimmed -- mjh]
  #5  
Old November 2nd 14, 05:53 PM posted to sci.astro.research
Eric Flesch
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Default A Laboratory Experiment for Astronomers ("Look-Back")

On Fri, 31 Oct 14 11:30:55 GMT, Phillip Helbig wrote:
writes:
travelling -- if they are travelling at c/2, then that fully explains
the redshift and kills the "expanding universe" stone cold dead.


Even assuming that that would be the case, i.e. this would rule out an
expaning universe, you still have to explain other consequences of the
expanding universe, such as the relative light-element abundances.


That's just the "shouting" part, as in "all over but the shouting".
If the available budgets and manpower were switched to "turtles all
the way down", I'll bet they'd make a rip-snorter of it. :-)

What about radio interferometry? It is routinely used to observe
objects at cosmological distances and I'm sure that the speed of light
enters into the equations somewhere. With VLBI, one has to correct for
continental drift and the fact that the Earth slows down in the northern
spring because there are more trees in the northern hemisphere, so it
would surprise me if a different photon speed had no effect.


Yes, and aberration was mentioned although I'm not seeing how that
would work. On the side, would gravitational lensing be larger if c
was smaller?
  #6  
Old November 2nd 14, 06:04 PM posted to sci.astro.research
Eric Flesch
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Posts: 321
Default A Laboratory Experiment for Astronomers ("Look-Back")

On Fri, 31 Oct 14, jacob navia wrote:
After the moon passes, if the speed of the quasars photons is c/2 we
should start seeing the quasar a whooping 0.5 seconds later as the
nearby star isn't it?


True, but those annoying ridges and craters on the moon's profile
would be hard to calculate in. Nice idea, though. Maybe would work
with Neptune.
  #7  
Old November 4th 14, 06:24 PM posted to sci.astro.research
Eric Flesch
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Posts: 321
Default A Laboratory Experiment for Astronomers ("Look-Back")

On Sun, 02 Nov 14 17:04:04 GMT, Eric Flesch wrote:
Maybe would work with Neptune.


Pursuant to this, we need occultation profiles of Uranus and Neptune,
in other words, the inner and outer edges of these planets where star
dimming begins and the star is fully extinguished.

What I have in mind in that if Neptune occults a z=1 quasar, and if
the photons from that z=1 quasar travel at only c/2, but the photons
from Neptune travel at c, then as Neptune passes before the quasar we
will see the quasar continue to shine for a while when it should have
been extinguished. Hmm, but we can't see it in Neptune's face...

How about this then: after Neptune passes, we won't see the quasar
again until its slower light reaches us. Quick back-of-the-envelope
calaculation: Light takes 5.5 hours to reach us from Neptune,
therefore if the light from the z=1 quasar travels at c/2, its light
will take 11 hours to arrive from there. Therefore there is a 5.5
hour lag for the quasar's light to arrive after Neptune uncovers it.

So we keep the telescope on that quasar after Neptune uncovers it and
we shouldn't be able to see it for 5.5 hours thereafter, and then it
will suddenly wink into existence. Howzat?

Who will do a back-of-the-envelope calculation on how long it takes
Neptune to move its own diameter on the sky? This could turn into an
easy observation to make, apart from how long till the next
occultation of a quasar by a large planet.

Eric
  #8  
Old November 4th 14, 06:26 PM posted to sci.astro.research
Steve Willner
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Default A Laboratory Experiment for Astronomers ("Look-Back")

In article ,
Eric Flesch writes:
If Barbour's well-published "relative scale" is operative, then z=1
photons were emitted under an earlier "scale" state, and it is
possible that they are travelling at speeds slower than c


I think this is pretty much ruled out by existing observations.
Optical spectrographs measure wavelength. Radio spectrographs
measure frequency. Both methods give the same redshift for high-z
galaxies; therefore the photons have to be traveling at the same
speed as any other photons to within the combined measurement
uncertainties.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
  #9  
Old November 4th 14, 06:27 PM posted to sci.astro.research
Eric Flesch
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Posts: 321
Default A Laboratory Experiment for Astronomers ("Look-Back")

My back-of-the-envelope calculation is that Neptune travels its own
diameter in 2.5 hours. At its distance, if the light from a z=1
quasar is travelling at c/2, its travel time to Earth is 5.5 hours
retarded behind Neptune's light. Therefore if Neptune occults a z=1
quasar, the entire occultation would be seen after Neptune has passed.
So about 1 diameter away from Neptune, after Neptune has crossed over
the quasar, we would see the quasar winking out, then switching back
on after 2.5 hours. Would be easy to see with any telescope large
enough to monitor the quasar continuously.

Who wants to do this observation? And who can find when a large
planet occults a sufficiently bright quasar any time soon?

cheers,
Eric
  #10  
Old November 5th 14, 10:39 AM posted to sci.astro.research
Eric Flesch
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Posts: 321
Default A Laboratory Experiment for Astronomers ("Look-Back")

On Tue, 04 Nov 14, Steve Willner wrote:
Eric Flesch writes:
possible that [z=1 photons] are travelling at speeds slower than c


I think this is pretty much ruled out by existing observations.
Optical spectrographs measure wavelength. Radio spectrographs
measure frequency. Both methods give the same redshift for high-z
galaxies; therefore the photons have to be traveling at the same
speed as any other photons


Not sure you've thought that through, Steve. If a 4000A photon is
redshifted z=1, then we say we see an 8000A wavelength but that
quantification is predicated on the photon travelling at c. If that
photon is travelling at c/2 then its wavelength remains at 4000A,
although the effect is the same as 8000A at c. Wavelength x frequency
still totals to the photon speed.

[Mod. note: I have to say I'm failing to see why you think wavelength
measurements are based on an assumption about speed -- mjh]

Momentum would be less though, would it not? That would be another
laboratory test of the z=1 photons, that they have less momentum than
otherwise-identical local photons. We need some lab boys!

Eric
 




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