Quasar found 13 billion years away

On Jul 6, 4:42 pm, (Phillip Helbig---
remove CLOTHES to reply) wrote:
In article , Chalky

writes:
One final point on this subject:

^^^^^
???

George Dishman pointed out some time ago that all radio telescopes
radiate heat to the night sky, until thermal equilibrium is reached.

Everything radiates heat to everything, until thermal equilibrium is
reached (in which case it still radiates, but absorbs just as much).

Ergo, a microwave dish capable of detecting black body radiation at
2.7 K, is also a 2.7 K black body radiator, whose own radiation is in
thermal equilibrium with its own matter.

The conclusion doesn't follow from the premises. Assume I have
something which is COLDER than the surroundings. It can absorb heat,
but is not in thermal equilibrium.

Radio dishes are NOT colder than the night sky. Voluminous information
supplied by NASA and others, via George Dishman and moderator, under
"Ranging & Pioneer" and "Still Lower Noise Radio Astronomy"

Therefore, we cannot say with any certainty where, and, more
importantly, when, the observed CMB came from.

Are you seriously suggesting this?

Yes

There are four interesting things about the CMB. First, there is a
strong dipole, which is consistent with our motion relative to the bulk
of the unuiverse.

Please amplify on this

Second, when the dipole is removed, one is left with
a very exact black-body spectrum.

This follows precisely from the relativistic principles of isotropy
and homogeneity.
You seem to be arguing from my corner here.

Third, the signal is the same from
every direction.

Ditto. See above. Note, however, anisotropy in the galactic plane.

Fourth, at a very low level, there are inhomogeneities
consistent with theoretical predictions.

Also consistent with temperature fluctuations consistent with galactic
clumping. What is your point?

Any alternative model would
have to explain ALL four points without any ad-hoc hypotheses.

I have made no ad hoc hypothesis. Please amplify on dipole objection.

In article , Chalky
writes:

Ergo, a microwave dish capable of detecting black body radiation at
2.7 K, is also a 2.7 K black body radiator, whose own radiation is in
thermal equilibrium with its own matter.

The conclusion doesn't follow from the premises. Assume I have
something which is COLDER than the surroundings. It can absorb heat,
but is not in thermal equilibrium.

Radio dishes are NOT colder than the night sky. Voluminous information
supplied by NASA and others, via George Dishman and moderator, under
"Ranging & Pioneer" and "Still Lower Noise Radio Astronomy"

That's not what I was implying. You seem to think that if it can
absorb, it is in thermal equuilibrium. I mentioned the example of a
cold object as an obvious example of something which is not in thermal
eqilibrium but can absorb heat. (Many radiation detectors ARE cooled,
of course.)

Therefore, we cannot say with any certainty where, and, more
importantly, when, the observed CMB came from.

Are you seriously suggesting this?

Yes

Extraordinary claims demand extraordinary evidence. The ball is in your
court.

There are four interesting things about the CMB. First, there is a
strong dipole, which is consistent with our motion relative to the bulk
of the unuiverse.

Please amplify on this

Even before the CMB was measured accurately, we had a rough idea of our
own peculiar motion (look up "Great Attractor"). The CMB dipole is in
the same direction. Any alternative theory would have to explain this
without ad-hoc hypotheses.

Second, when the dipole is removed, one is left with
a very exact black-body spectrum.

This follows precisely from the relativistic principles of isotropy
and homogeneity.
You seem to be arguing from my corner here.

I'm just noting the four important things; you might not disagree with
all of them. :-)

Third, the signal is the same from
every direction.

Ditto. See above. Note, however, anisotropy in the galactic plane.

That isn't the CMB, but rather the CMF ("F" as in "foreground").

Fourth, at a very low level, there are inhomogeneities
consistent with theoretical predictions.

Also consistent with temperature fluctuations consistent with galactic
clumping. What is your point?

No. Take a robust feature, such as the position of the first peak in
the spectrum, and name me ANY alternative theory which predicts this.
In fact, the shape of the spectrum has been used to rule out various
alternative models such as topological defects. (We are talking about
the power spectrum here, the amount of variation as a function of
angular scale.)

Any alternative model would
have to explain ALL four points without any ad-hoc hypotheses.

I have made no ad hoc hypothesis.

I don't mean your original hypothesis, but rather that if it turns out
that your hypothesis needs to explain other things, then they should
follow in a natural way from your hypothesis, and not be ad-hoc
additions.

Chalky wrote:

Radio dishes are NOT colder than the night sky.

There's no reason they need to be, they are
passive reflection devices, and presumably
are in rough thermal equilibrium with the
local atmosphere, due to conduction, not with
the "night sky" due to radiation.

What is kept cold is the detector electronics,
as you can read about in this school science
club tour writeup, with nice photos:

http://www.sciencearuba.com/news/2005/topstory21.php

"The box containing all the electronic parts
is cooled down to 70 Kelvin that is -203 =BA
Celsius."

And IIUC, that's _still_ much warmer than the
equivalent temperature of the CMBR, one of the
reasons you need such a big concentrator to
make the sky signal dominate the local noise
sources.[*]

Quantum valeat.

xanthian.
[*] Besides just that you need that much antenna
due to the wavelengths you're studying.

"Chalky" wrote in message
...
On Jun 28, 8:08 am, Richard Saam wrote:
Chalky wrote:
So, why wouldn't the thermal radiation from this known expanding cloud
of hot transparent gas, after the surface of last scattering, produce,
or, at least, contribute to, the observed CMB spectrum?

If something re-absorbs that thermal radiation, why does it not
simultaneously re-absorb the classically predicted CMBR, which we are
taught was only released at this surface of last scattering?

Possibly because most of the universe mass/energy at
1+z~1000, T~3000
was 'dark matter/energy' at temperature Td
in equilibrium ~T/Td with CMBR at that time
just as it is now ~T/Td at
1+z~1, T~3

One final point on this subject:

George Dishman pointed out some time ago that all radio telescopes
radiate heat to the night sky, until thermal equilibrium is reached.

Many respondents, including George, have pointed out that any
efficient radiator is also an equally efficient absorber, at the same
wavelength.

Ergo, a microwave dish capable of detecting black body radiation at
2.7 K, is also a 2.7 K black body radiator,

You jumped a step. The electrons in the HEMT transistors
reach equilibrium which means the heat being coupled to
them as a result of being in a physical piece of silicon
is balanced by their radiation to space. That is at an
electron temperature of around 20K from memory, not 2.7K.

The sensitive detectors are measuring to tiny fractions
of a degree so use differential techniques, for example
comparing the signal from a block at a known temperature
to the antenna signal, and use chopping to so that the
difference is AC while the receiver thermal noise which
is always present produces DC. Much of the real scientific
work in such missions as COBE is related to the instrument
design.

whose own radiation is in
thermal equilibrium with its own matter.

Therefore, we cannot say with any certainty where, and, more
importantly, when, the observed CMB came from.

You cannot be serious.

One final point for you. Your original point relates to
opacity of the neutral hydrogen gas after recombination.
You may already be aware but if not I think you would
find it of interest to look the characteristics and cause
of the Lyman Alpha "forest". Specifically, why are there
gaps between the trees ;-)

George

On Jul 8, 8:57 pm, (Phillip Helbig---
remove CLOTHES to reply) wrote:
In article , Chalky

writes:
Ergo, a microwave dish capable of detecting black body radiation at
2.7 K, is also a 2.7 K black body radiator, whose own radiation is in
thermal equilibrium with its own matter.

The conclusion doesn't follow from the premises. Assume I have
something which is COLDER than the surroundings. It can absorb heat,
but is not in thermal equilibrium.

Radio dishes are NOT colder than the night sky. Voluminous information
supplied by NASA and others, via George Dishman and moderator, under
"Ranging & Pioneer" and "Still Lower Noise Radio Astronomy"

That's not what I was implying. You seem to think that if it can
absorb, it is in thermal equuilibrium. I mentioned the example of a
cold object as an obvious example of something which is not in thermal
eqilibrium but can absorb heat. (Many radiation detectors ARE cooled,
of course.)

Therefore, we cannot say with any certainty where, and, more
importantly, when, the observed CMB came from.

Are you seriously suggesting this?

Yes

Extraordinary claims demand extraordinary evidence. The ball is in your
court.

There are four interesting things about the CMB. First, there is a
strong dipole, which is consistent with our motion relative to the bulk
of the unuiverse.

Please amplify on this

Even before the CMB was measured accurately, we had a rough idea of our
own peculiar motion (look up "Great Attractor"). The CMB dipole is in
the same direction.

I was asking you to amplify on what is meant by CMB dipole

Any alternative theory would have to explain this
without ad-hoc hypotheses.

Second, when the dipole is removed, one is left with
a very exact black-body spectrum.

This follows precisely from the relativistic principles of isotropy
and homogeneity.
You seem to be arguing from my corner here.

I'm just noting the four important things; you might not disagree with
all of them. :-)

OK, so we are agreed that point 2 is not a valid objection. first
point to me.

Third, the signal is the same from
every direction.

Ditto. See above. Note, however, anisotropy in the galactic plane.

That isn't the CMB, but rather the CMF ("F" as in "foreground").

So what? Second point to me, I make it.

Fourth, at a very low level, there are inhomogeneities
consistent with theoretical predictions.

Also consistent with temperature fluctuations consistent with galactic
clumping. What is your point?

No. Take a robust feature, such as the position of the first peak in
the spectrum,

I don't know what you are talking about here. Please give us a
hyperlink to the pertinent graph.

and name me ANY alternative theory which predicts this.
In fact, the shape of the spectrum has been used to rule out various
alternative models such as topological defects. (We are talking about
the power spectrum here, the amount of variation as a function of
angular scale.)

Any alternative model would
have to explain ALL four points without any ad-hoc hypotheses.

I have made no ad hoc hypothesis.

I don't mean your original hypothesis, but rather that if it turns out
that your hypothesis needs to explain other things, then they should
follow in a natural way from your hypothesis, and not be ad-hoc
additions.

I am in complete agreement with you there.

Show me my ad hoc assumptions, and I will show you yours.

C

On Jul 8, 9:00 pm, Kent Paul Dolan wrote:
Chalky wrote:
Radio dishes are NOT colder than the night sky.

There's no reason they need to be, they are
passive reflection devices

I was expecting the expert (DishMan) to pick up on this. I am, of
course, really talking about the radio telescope, i.e. dish + antenna.

, and presumably
are in rough thermal equilibrium with the
local atmosphere, due to conduction, not with
the "night sky" due to radiation.

The 'local atmosphere' of the Wilkinson Microwave Anisotropy Probe
being?

C

In article , Chalky
writes:

There are four interesting things about the CMB. First, there is a
strong dipole, which is consistent with our motion relative to the bulk
of the unuiverse.

Please amplify on this

Even before the CMB was measured accurately, we had a rough idea of our
own peculiar motion (look up "Great Attractor"). The CMB dipole is in
the same direction.

I was asking you to amplify on what is meant by CMB dipole

The temperature is increased in one direction and decreased in the
other. It is increased in the direction in which we are moving, which
was known (but not so precisely) before the detection of the CMB dipole.

No. Take a robust feature, such as the position of the first peak in
the spectrum,

I don't know what you are talking about here. Please give us a
hyperlink to the pertinent graph.

Seriously, if you are discususing the CMB and don't IMMEDIATELY know
what "the position of the first peak in the spectrum" is, then you need
to do some serious background research.

Googling for "+CMB +peak +spectrum" gives 239 thousand hits. Take it
from there.

Check out

http://relativity.livingreviews.org/...age=fig21.html

which I got from

http://relativity.livingreviews.org/...ge=node20.html

which is one of the hits on the first page. We are talking about the
obvious big peak near an l value of 300. (Note: this figure is 10 years
old; there are MUCH more precise measurements available now.)

On Jul 9, 4:42 pm, (Phillip Helbig---
remove CLOTHES to reply) wrote:
In article , Chalky

writes:
There are four interesting things about the CMB. First, there is a
strong dipole, which is consistent with our motion relative to the bulk
of the unuiverse.

Please amplify on this

Even before the CMB was measured accurately, we had a rough idea of our
own peculiar motion (look up "Great Attractor"). The CMB dipole is in
the same direction.

I was asking you to amplify on what is meant by CMB dipole

The temperature is increased in one direction and decreased in the
other.

I thought so!

In that case, this objection, too, is groundless, and without
foundation.

Prediction of the CMB dipole thus follows naturally from the known
fact that c = constant, and the known fact that thermal and optical
radiation are both electromagnetic.

When WMAP points in a given direction, it achieves thermal equilibrium
with the night sky in that direction. Since this temperature
information is communicated electromagnetically, it is obvious that
the temperature measured by WMAP is Doppler shifted by our own
peculiar motion.

To conclude otherwise, you must introduce the additional ad-hoc
hypothesis that thermal radiation is not electromagnetic.

As I have already also posted under the other title, "Dark Matter (&
Mass) of Milky Way":

show me my ad hoc assumptions, and I will show you yours.


Point 4 to me, too, I think.


It is increased in the direction in which we are moving, which
was known (but not so precisely) before the detection of the CMB dipole.


Chalky

On Jul 9, 4:42 pm, (Phillip Helbig---
remove CLOTHES to reply) wrote:
In article , Chalky

writes:
There are four interesting things about the CMB. First, there is a
strong dipole, which is consistent with our motion relative to the bulk
of the unuiverse.

Please amplify on this

Even before the CMB was measured accurately, we had a rough idea of our
own peculiar motion (look up "Great Attractor"). The CMB dipole is in
the same direction.

I was asking you to amplify on what is meant by CMB dipole

The temperature is increased in one direction and decreased in the
other. It is increased in the direction in which we are moving, which
was known (but not so precisely) before the detection of the CMB dipole.

No. Take a robust feature, such as the position of the first peak in
the spectrum,

I don't know what you are talking about here. Please give us a
hyperlink to the pertinent graph.

Seriously, if you are discususing the CMB and don't IMMEDIATELY know
what "the position of the first peak in the spectrum" is, then you need
to do some serious background research.

Googling for "+CMB +peak +spectrum" gives 239 thousand hits. Take it
from there.

You are the one who raised this 5th objection. If you are not prepared
to disclose what the objection actually is, I do not have the spare
time to wade through 239 thousand references in order to divine what
it might be.

Check out

http://relativity.livingreviews.org/...-11&page=fig21...

I have. I do not understand why this is inconsistent with the
predicted black body spectrum radiated (in accordance with Planck's
solution of the Ultraviolet Catastrophe) from a night sky with a
temperature of ~ 2.7K


Please explain.


C

On 9 Jul, 09:54, Chalky wrote:
On Jul 8, 9:00 pm, Kent Paul Dolan wrote:

Chalky wrote:
Radio dishes are NOT colder than the night sky.

There's no reason they need to be, they are
passive reflection devices

I was expecting the expert (DishMan) to pick up on this. I am, of
course, really talking about the radio telescope, i.e. dish + antenna.

I thought Kent had covered it but I suppose it goes
back to the previous discussion about the link between
transparency and emission. The same argument applies
to the dish, a perfect reflector doesn't absorb any of
the incident light, and if it doesn't absorb, it cannot
emit either.

George