Is LIGO just observing viscosity of the vacuum?
dud...@gmail.com
gravitational waves from sources millions of light years away - we are
assuming that their strength decreases like R^-3.
But because of this distance, even slightest interactions with the
vacuum and other objects on the way, could diffuse/absorb them - and
so the amplitude would decrease exponentially, making such
observations completely hopeless.
In November 2005 LIGO has reached assumed sensitivity
" At its conclusion, S5 had achieved an effective range of more than
15 Mpc for the four-kilometer interferometers, and seven Mpc for the
two-kilometer interferometer."
http://www.ligo.caltech.edu/~ll_news/s5_news/s5article.htm
But for these 3.5 years its only success is is a non-detection:
"During the intense blast of gamma rays, known as GRB070201, the 4-km
and 2-km gravitational-wave interferometers at the Hanford facility
were in science mode and collecting data. They did not, however,
measure any gravitational waves in the aftermath of the burst.
That non-detection was itself significant. "
http://mr.caltech.edu/media/Press_Releases/PR13084.html
What is vacuum?
It definitely isn't just 'an empty space' - it for example is a medium
for many different waves, particles.
Nowadays many people believe that it can for example spontaneously
create particle-antiparticle pairs...
Modern cosmological models says that there is required cosmological
constant - additional density of energy of ... this vacuum ...
Anyway, even being only a medium for many kind of interactions - there
is at least some field there - it has many internal degrees of freedom
(like microwave radiation).
We rather believe that they could somehow interact with each other, so
there should be thermalization - all of them should contain similar
amount of energy.
In physics there are usually no perfect mediums - there are always at
least some very very very small interactions...
We observe more or less uniform 2.725K microwave radiation - it is
believed to be created in about 3000K and then reduce the wavelength
due to red shift in expanding universe.
But assume that the field of which vacuum is build is not perfectly
transparent - for example that such photons interacts at average once
per a million years - that would be already enough for thermalisation
process.
So if the field of the vacuum is not perfectly transparent (there is
interaction between different interactions), its internal degrees of
freedom should have temperature 2.725K.
We observe only electromagnetic degrees of freedom (according to
Wikipedia: about 6*10^-5 of total density of universe), but we know
well that there is more types of interactions...
And their energies probably sum up to the cosmological constant...
Returning to the question from topic - general relativity theory says
that vacuum is kind of fluid for gravitational waves.
It it already a field - it has some internal structure ... and there
is QED, QCD, etc - I just don't believe we can assume that it's a
perfect medium.
For fluids this kind of friction - converting macroscopic energy into
internal degrees of freedom - is called viscosity (try to make waves
on honey).
If there is some extremely small viscosity of vacuum (which has
nonzero energy density/temperature), multiplying it by millions of
light years, it could essentially reduce strength of gravitational
waves reaching earth...
And the are are already believed to be extremely weak...
Do You think it is why LIGO only astronomical success is a non-
detection?
If not - why is that?
Juan R.
> In experiments like LIGO we want to observe extremely weak gravitational
> waves from sources millions of light years away
It is not clear to me *what* they want to measure. Sometimes it seems to
me they wait to observe gravitational waves that transport energy in the
usual (field theoretic) sense. Sometimes it seems they wait to detect
spacetime riples, which do not transport energy according to a strict
interpretation of general relativity formalism. The situation is still
poor with most of authors confounding both concepts and confounding the
wave equation for a spin-2 field with Einstein relaxed metric equations up
to first order.
> What is vacuum?
Basically it is a particle physicists' invention arising from the
*harmonic* oscillator model for the unobservable concept called field [#].
> Modern cosmological models says
> that there is required cosmological constant - additional density of
> energy of ... this vacuum ...
And the difference between the computed value and the observed value gives
the biggest mistake of physics ever: about 120 orders of magnitude!
> Returning to the question from topic - general relativity theory says
> that vacuum is kind of fluid for gravitational waves.
The concept of vaccuum is microscopic and was developed by particle
physicists many years after that GR were formulated. In rigor, there is
not concept of quantum vacuum in GR. Sometimes T_ab^{DARK} is interpreted
as macroscopic observable would corespond to a quantum vaccuum. That is
all.
> Do You think it is why LIGO only astronomical success is a non-
> detection?
> If not - why is that?
I suspect on the existence of gravitational waves, and think are the
physical mechanism behind binary pulsar anomaly, but of course a direct
experimental confirmation is needed.
Since I have not studied all LIGO literature in detail, but I know that
most of literature in gravitational waves confounds the metric formulation
of GR, and its predicted non-observable spacetime riples, with the
gravitational waves (*both* spin-0 and spin-2) predicted by field theory
of gravity worked by Feynman and others.
[#] I know that I have said above and it is exact. Do not try to make
arguments about *indirect* support of the concept of vacuum, because the
*same indirect observations* can are compatible with theories without any
superfluous vaccuum.
--
http://www.canonicalscience.org/
Usenet Guidelines:
http://www.canonicalscience.org/en/miscellaneouszone/guidelines.html
dud...@gmail.com
> It is not clear to me *what* they want to measure. (...)
Such detector is kind of (expensive and) universal tool - can be used
to verify different hypothesis and so it's not strange that they want
to get the best of it.
> > What is vacuum?
> Basically it is a particle physicists' invention arising from the
> *harmonic* oscillator model for the unobservable concept called field [#].
For me this 'harmonic' model is only a mathematical trick allowing us
to calculate analytically some cases.
Such 'particles' couldn't even be stable ...
The problem is that it (and so its infinities) are taken too
seriously...
The longer I think about it, the closer I am to that everything can be
describe by some relatively simple classical field theory
(fourdimensional, CPT conserving).
The problem is that they lead to extremely complicated mathematics -
its difficult to work on it without quantization approach...
http://groups.google.com/group/sci.physics.research/browse_thread/thread/9c4f433725f75638/9da56171153421ba
> And the difference between the computed value and the observed value gives
> the biggest mistake of physics ever: about 120 orders of magnitude!
Yes - it's one of problems of taking quantization too seriously.
So let's forget about particle-antiparticle creation and look at it
thermodynamically - we have huge amount of degrees of freedom - for
EM, weak, strong, gravitational (...) interactions and they interact
with each other, what leads to thermalisation.
We can see only EM (microwave radiation), but the rest of them should
have the same temperature and probably after summing up, give the
cosmological constant.
> I suspect on the existence of gravitational waves, and think are the
> physical mechanism behind binary pulsar anomaly, but of course a direct
> experimental confirmation is needed.
LIGO is a large and precise interferometer and it is checked that it
should work properly.
The only conformation they get is that they should detect something,
but they couldn't (GRB070201) - for me it's strong argument that these
waves were absorbed on their way to us...
Eric Gisse
> In experiments like LIGO we want to observe extremely weak
> gravitational waves from sources millions of light years away - we are
> assuming that their strength decreases like R^-3.
Wrong distance, wrong falloff.
http://en.wikipedia.org/wiki/LIGO
The falloff in distance depends entirely on the source type. Fields
for spherical sources fall off as 1/r^2, cylindrical falls off as 1/r,
etc.
> But because of this distance, even slightest interactions with the
> vacuum and other objects on the way, could diffuse/absorb them - and
> so the amplitude would decrease exponentially, making such
> observations completely hopeless.
Wrong. Like I told you *elsewhere*, the radiation couples to mass
quadrupole moments. Those are extremely weak. Interaction with matter
is essentially non-existent.
[...]
> What is vacuum?
Not a fluid. Please stop re-posting the same thing to every physics
newsgroup you can find.
[snip]
======================================= MODERATOR'S COMMENT:
Indeed, cross-posting is forbidden by charter
Eric Gisse
<juanREM...@canonicalscience.com> wrote:
> dudajar wrote on Sun, 19 Apr 2009 06:32:10 -0600:
>
> > In experiments like LIGO we want to observe extremely weak gravitational
> > waves from sources millions of light years away
>
> It is not clear to me *what* they want to measure.
Perhaps you should do some light reading, then.
The mechanism LIGO uses is extensively discussed in MTW, as well as on
their web page.
http://www.ligo.caltech.edu/LIGO_web/about/brochure.html
> Sometimes it seems to
> me they wait to observe gravitational waves that transport energy in the
> usual (field theoretic) sense. Sometimes it seems they wait to detect
> spacetime riples, which do not transport energy according to a strict
> interpretation of general relativity formalism.
Yes, some light reading is definitely in order. LIGO's detector does
not work on the basis of absorbing the waves.
Chapter 37 in MTW would be worth reading. Carroll goes into
significant detail about LIGO specifically but you don't seem to
respect him....
>The situation is still
> poor with most of authors confounding both concepts and confounding the
> wave equation for a spin-2 field with Einstein relaxed metric equations up
> to first order.
Why are you saying the understanding of _other_ authors is poor when
you yourself are saying you are confused?
The attempts at quantizing the linearized limit of GR have nothing to
do with gravitational wave observations.
>
> > What is vacuum?
>
> Basically it is a particle physicists' invention arising from the
> *harmonic* oscillator model for the unobservable concept called field [#].
Again, quantum mechanics is irrelevant here. The answer _clearly_
needs to be in the context of general relativity.
[...]
> Since I have not studied all LIGO literature in detail,
Then don't make accusations about the understanding of other
scientists.
> but I know that
> most of literature in gravitational waves confounds the metric formulation
> of GR
When one person says everyone else is confused, who is the one that is
_actually_ confused?
>, and its predicted non-observable spacetime riples, with the
> gravitational waves (*both* spin-0 and spin-2) predicted by field theory
> of gravity worked by Feynman and others.
GR is a classical theory.
Gravitational waves can't be spin-0, by the way.
[...]
Juan R.
(...)
> The longer I think about it, the closer I am to that everything can be
> describe by some relatively simple classical field theory
> (fourdimensional, CPT conserving).
No, classical field theory has always been an inconsistent theory. The
belief was that quantum field theory would solve its inconsistencies, but
did not. Moreover, classical field theory cannot explain all observed
phenomena.
(...)
>> And the difference between the computed value and the observed value
>> gives the biggest mistake of physics ever: about 120 orders of
>> magnitude!
>
> Yes - it's one of problems of taking quantization too seriously.
No. The problem has a different origin (the geometrical model of GR), and
the cosmological constant problem is absent in non-geometrical theories of
gravity, which are 100% compatible with quantum field theory and the
Standard Model.
(...)
>> I suspect on the existence of gravitational waves, and think are the
>> physical mechanism behind binary pulsar anomaly, but of course a direct
>> experimental confirmation is needed.
>
> LIGO is a large and precise interferometer and it is checked that it
> should work properly.
> The only conformation they get is that they should detect something, but
> they couldn't (GRB070201) - for me it's strong argument that these waves
> were absorbed on their way to us...
Any large-scale experiment as LIGO is built over a theoretical basis, and
my impression is that the theoretical basis for this one is misguided.
As explained in a previous message, most of literature in gravitational
waves confoundes spin-2 field equations with Einstein relaxed equations.
At the one hand, they say me about their desire to detect gravitational
waves. Then I infer that they want test field equations for weak waves. At
the other hand, they say me that gravitational waves would alter the
interferometer space-time area. But then they are talking about spacetime
riples not about gravitational waves; moreover, those spacetime riples are
not observable according to metrological interpretation of GR. Therefore,
what are really doing?
Could you explain to me what of above two equations they are using for
interpreting data? It was never clear to me.
Juan R.
(...)
> The mechanism LIGO uses is extensively discussed in MTW, as well as on
> their web page.
>
> http://www.ligo.caltech.edu/LIGO_web/about/brochure.html
Except that nothing of this addresses the questions I raised. Questions
you just *ignored* in this response.
>> Sometimes it seems to
>> me they wait to observe gravitational waves that transport energy in
>> the usual (field theoretic) sense. Sometimes it seems they wait to
>> detect spacetime riples, which do not transport energy according to a
>> strict interpretation of general relativity formalism.
>
> Yes, some light reading is definitely in order. LIGO's detector does not
> work on the basis of absorbing the waves.
I don't remember writting something about "absorbing the waves", but
merely emphasizing the different physical nature of both concepts.
But you can provide a quotation from mine, if you think the contrary.
> Chapter 37 in MTW would be worth reading. Carroll goes into significant
> detail about LIGO specifically but you don't seem to respect him....
MTW, Carroll, Weinberg, and even Will review I cited in a previous
message, in another thread, also deal with the topic, but all those are
instances of the literature confusion noticed in the message which you are
replying now.
For instance Carroll confounds the "conventional relativistic wave
equation" with the Relaxed Einstein equations at first order in the
harmonic gauge.
(...)
>>, and its predicted non-observable spacetime riples, with the
>> gravitational waves (*both* spin-0 and spin-2) predicted by field
>> theory of gravity worked by Feynman and others.
>
> GR is a classical theory.
I am pretty sure that every reader of spf knows that!
The relation between the spin of an underlying quantum theory and the
number of (tensor) indices of the classical limit is *so* close, that it
is usual for scientists to refer to the number of indices on the classical
wave equation with a (quantum) spin degree.
If you read Wald textbook, he writtes:
The full theory of general relativity thus may be viewed as that of a
massless spin-2 'field' which undergoes a nonlinear self-interaction.
Of course, by refering to spin, Wald is *not* saying that general
relativity was a quantum theory. When I referred to spin I was not saying
that general relativity was a quantum theory.
> Gravitational waves can't be spin-0, by the way.
Another totally wrong comment.
The spacetime ripples on general relativity are spin-2, but gravitational
waves in nonlinear field theory are *both* spin-2 and spin-0.
I emphasized the word *both* in my previous message, but you decided to
answer anyway... just repeating the confusion between both concepts that I
had *noticed* in my message.
If you study a nonlinear field theory of gravity, you will see that spin-0
equations describe scalar gravitational waves.
There is enough literature in the topic of "scalar gravitational waves"
associated to generalizations of general relativity, including their
possible observation. Even a simple search by Google reports links
http://www.google.es/search?q=scalar+gravitational+waves
Moreover, In the draft about Newtonian limits of different theories of
gravity, I devote part of the section "Confrontation between theories,
experiment, and observations" to revise the possibility that scalar
gravitational waves have been (indirectly) detected in high precision
binary pulsar data.
Eric Gisse
<juanREM...@canonicalscience.com> wrote:
> Eric Gisse wrote on Mon, 20 Apr 2009 02:14:28 -0600:
>
> (...)
>
> > The mechanism LIGO uses is extensively discussed in MTW, as well as on
> > their web page.
>
> >http://www.ligo.caltech.edu/LIGO_web/about/brochure.html
>
> Except that nothing of this addresses the questions I raised. Questions
> you just *ignored* in this response.
You sure? From the page:
"The space-time ripples cause the distance measured by a light beam to
change as the gravitational wave passes by, causing the amount of
light falling on the photodetector to vary. The photodetector then
produces a signal telling how the light falling on it changes over
time. "
Slight differences in path length induced by a traversing wave are
seen by the interferometer. Does this settle the question of what is
being observed?
>
> >> Sometimes it seems to
> >> me they wait to observe gravitational waves that transport energy in
> >> the usual (field theoretic) sense. Sometimes it seems they wait to
> >> detect spacetime riples, which do not transport energy according to a
> >> strict interpretation of general relativity formalism.
>
> > Yes, some light reading is definitely in order. LIGO's detector does not
> > work on the basis of absorbing the waves.
>
> I don't remember writting something about "absorbing the waves", but
> merely emphasizing the different physical nature of both concepts.
"Sometimes it seems to me they wait to observe gravitational waves
that transport energy in the
usual (field theoretic) sense."
I am curious to know how you would determine that they transport
energy without absorbing them.
>
> But you can provide a quotation from mine, if you think the contrary.
>
> > Chapter 37 in MTW would be worth reading. Carroll goes into significant
> > detail about LIGO specifically but you don't seem to respect him....
>
> MTW, Carroll, Weinberg, and even Will review I cited in a previous
> message, in another thread, also deal with the topic, but all those are
> instances of the literature confusion noticed in the message which you are
> replying now.
>
> For instance Carroll confounds the "conventional relativistic wave
> equation" with the Relaxed Einstein equations at first order in the
> harmonic gauge.
What's the difference? A gauge has been picked in both instances, and
in both instances it is a proper wave equation.
I'm always more inclined to give active, published, researchers the
benefit of the doubt.
>
> (...)
>
> >>, and its predicted non-observable spacetime riples, with the
> >> gravitational waves (*both* spin-0 and spin-2) predicted by field
> >> theory of gravity worked by Feynman and others.
>
> > GR is a classical theory.
>
> I am pretty sure that every reader of spf knows that!
One would hope.
>
> The relation between the spin of an underlying quantum theory and the
> number of (tensor) indices of the classical limit is *so* close, that it
> is usual for scientists to refer to the number of indices on the classical
> wave equation with a (quantum) spin degree.
I always thought it was the number of polarization modes. There's
probably an equivalence given spin has units of angular momentum.
>
> If you read Wald textbook, he writtes:
>
> The full theory of general relativity thus may be viewed as that of a
> massless spin-2 'field' which undergoes a nonlinear self-interaction.
>
> Of course, by refering to spin, Wald is *not* saying that general
> relativity was a quantum theory. When I referred to spin I was not saying
> that general relativity was a quantum theory.
>
> > Gravitational waves can't be spin-0, by the way.
>
> Another totally wrong comment.
>
> The spacetime ripples on general relativity are spin-2, but gravitational
> waves in nonlinear field theory are *both* spin-2 and spin-0.
They could be spin-32 in another theory. My context is always general
relativity unless otherwise noted.
>
> I emphasized the word *both* in my previous message, but you decided to
> answer anyway... just repeating the confusion between both concepts that I
> had *noticed* in my message.
What confusion? Different theories predict different things. The
answer is very specific within a context of general relativity.
Scalar-tensor theories have scalar and tensor waves.
>
> If you study a nonlinear field theory of gravity, you will see that spin-0
> equations describe scalar gravitational waves.
Only when there's a scalar coupling to the action. Which not every
theory has.
>
> There is enough literature in the topic of "scalar gravitational waves"
> associated to generalizations of general relativity, including their
> possible observation. Even a simple search by Google reports links
>
> http://www.google.es/search?q=scalar+gravitational+waves
Yes, there is any number of alternate theories with odd couplings.
>
> Moreover, In the draft about Newtonian limits of different theories of
> gravity, I devote part of the section "Confrontation between theories,
> experiment, and observations" to revise the possibility that scalar
> gravitational waves have been (indirectly) detected in high precision
> binary pulsar data.
Doubt it. We have been over this before. The primary source for your
claims are dubious.
http://groups.google.com/group/sci.math/msg/18d9da152e336aa2?dmode=source
First off, the very first sentence is incorrect.
{BLOCKQUOTE
The most accurate observations of PSR1913 + 16 (Taylor et al.,1992)
revealed the existence of about 1% excess in energy losses which
could be interpreted as a scalar gravitational radiation with spin0.
Different forms of EMT give different values of the expected excess:
3% Baryshev (1982); 2.2% Sokolov (1992a); 0.735% Baryshev (1995a).
For the final decision there are required improvement of
measurements accuracy and account for possible non-gravity eects.
}
There is no such 1% excess. I can't tell from the original article as
I can't find a copy of it, but not one article that references it
mentions a 1% excess nor is any such excess shown in followup articles
by Taylor.
Furthermore, that was NOT the most accurate observation. Not by a long
shot.
arXiv:astro-ph/0407149v1
Given that the pulsar orbits are decaying within 0.13 +/- 0.21 %
according to Taylor, it sort-of puts the claim into a little bit of
doubt.
>
> --http://www.canonicalscience.org/
>
> Usenet Guidelines:http://www.canonicalscience.org/en/miscellaneouszone/guidelines.html
Juan R.
> On Apr 20, 6:18 am, "Juan R." González-
àlvarez
> <juanREM...@canonicalscience.com> wrote:
>> Eric Gisse wrote on Mon, 20 Apr 2009 02:14:28 -0600:
>>
>> (...)
>>
>> > The mechanism LIGO uses is extensively discussed in MTW, as well as
>> > on their web page.
>>
>> >http://www.ligo.caltech.edu/LIGO_web/about/brochure.html
>>
>> Except that nothing of this addresses the questions I raised. Questions
>> you just *ignored* in this response.
>
> You sure? From the page:
>
> "The space-time ripples cause the distance measured by a light beam to
> change as the gravitational wave passes by, causing the amount of light
> falling on the photodetector to vary. The photodetector then produces a
> signal telling how the light falling on it changes over time. "
>
> Slight differences in path length induced by a traversing wave are seen
> by the interferometer. Does this settle the question of what is being
> observed?
I already reported *that* in my response of Monday:
"At the one hand, they say me about their desire to detect gravitational
waves. Then I infer that they want test field equations for weak waves.
At the other hand, they say me that gravitational waves would alter the
interferometer space-time area. But then they are talking about
spacetime riples not about gravitational waves [...]
Your repetition, without answering the objections raised, is of no help.
(...)
>> I don't remember writting something about "absorbing the waves", but
>> merely emphasizing the different physical nature of both concepts.
>
> "Sometimes it seems to me they wait to observe gravitational waves that
> transport energy in the
> usual (field theoretic) sense."
>
> I am curious to know how you would determine that they transport energy
> without absorbing them.
Exactly, I did not wrote "absorbing the waves"...
>> But you can provide a quotation from mine, if you think the contrary.
and you could not provide any quotation from mine.
(...)
> I'm always more inclined to give active, published, researchers the
> benefit of the doubt.
I know you often argue by authority arguments, but authority is not a
valid argument in science.
(...)
>> > Gravitational waves can't be spin-0, by the way.
>>
>> Another totally wrong comment.
>>
>> The spacetime ripples on general relativity are spin-2, but
>> gravitational waves in nonlinear field theory are *both* spin-2 and
>> spin-0.
>
> They could be spin-32 in another theory. My context is always general
> relativity unless otherwise noted.
And again you confound spacetime ripples on general relativity with
gravitational waves in nonlinear field theory!
>> I emphasized the word *both* in my previous message, but you decided to
>> answer anyway... just repeating the confusion between both concepts
>> that I had *noticed* in my message.
>
> What confusion? (...) Scalar-tensor theories have scalar and tensor
> waves.
The confusion you repeat once again now. Scalar-tensor theories are metric
theories, they do not predict the scalar gravitational waves in field
theory of gravity.
>> If you study a nonlinear field theory of gravity, you will see that
>> spin-0 equations describe scalar gravitational waves.
>
> Only when there's a scalar coupling to the action.
This is another wrong assertion. If you study a nonlinear field theory of
gravity, you will see that scalar waves are not associated to "scalar
couplings to the action".
(...)
>> Moreover, In the draft about Newtonian limits of different theories of
>> gravity, I devote part of the section "Confrontation between theories,
>> experiment, and observations" to revise the possibility that scalar
>> gravitational waves have been (indirectly) detected in high precision
>> binary pulsar data.
>
> Doubt it. We have been over this before. The primary source for your
> claims are dubious.
>
> http://groups.google.com/group/sci.math/msg/18d9da152e336aa2?
dmode=source
This is pretty ridiculous. The primary source for my claims is not one
USENET old message in a noisy non-moderated group.
(...)
> Furthermore, that was NOT the most accurate observation. Not by a long
> shot.
>
> arXiv:astro-ph/0407149v1
>
> Given that the pulsar orbits are decaying within 0.13 +/- 0.21 %
> according to Taylor, it sort-of puts the claim into a little bit of
> doubt.
It is ironic that you cite above reference by Taylor and Weisberg, when it
is the reference number *17* in my draft.
Moreover, their recent work is basic for my discussion, of the
uncertainties in binary pulsar parameters and the link with the recent
claims by other authors of possible detection of scalar waves.
Above you write about 0.2% of error and you claim it is a most accurate
observation "by a long shot".
But in the draft I discuss radiation models -by other authors- to within
a 0.1% of error with available data.
--