| Topic: |
Science > Physics |
| User: |
"William J. Beaty" |
| Date: |
02 Nov 2004 11:31:15 PM |
| Object: |
Mr. Tompkins spreads viagra on his laser |
Gravity field of a photon.
1.
Suppose we launch a light pulse with a ridiculously powerful
laser. The pulse is a few cm across, a nS long, and has enough
energy that by E=MC^2 it weighs as much as a large asteroid. Will
this travelling light-pulse have its own gravity field? And, since
it's moving at C, won't it create a cone-shaped shock wave of
gravity (so we'd feel a big "thud" as the pulse flew past?)
2.
Instead let's put some extremely bright light into a small box with
100% reflecting walls. If the light is so bright that, as before,
it weighs as much as a large asteroid, won't the box have its own
gravity field? (Can a box full of energy NOT have mass?!!) Won't
the light within the box significantly attract the light in a nearby
similar box, so the two boxes fall together? And if we keep adding
more light, won't it eventually condense gravitationally, forming an
event horizon that scavenges up all the light in the box, so we can
safely open the lid and look inside without singing our eyebrows?
3.
Do individual photons have very weak gravitational shock waves?
Suppose we had a high frequency light source where the photon
energy was so large that individual photons could have measurable
gravity effects. Does a flying photon have a gravity field?
And what happens if this photon enters our 100% reflective box and
starts bouncing around inside? Does the box wiggle? Or does it
start emitting gravity waves?
((((((((((((((((((((((( ( ( (o) ) ) )))))))))))))))))))))))
William J. Beaty Research Engineer
beaty@chem.washington.edu UW Chem Dept, Bagley Hall RM74
billb@eskimo.com Box 351700, Seattle, WA 98195-1700
ph206-543-6195 http//staff.washington.edu/wbeaty/
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| User: "Ken S. Tucker" |
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| Title: Re: Mr. Tompkins spreads viagra on his laser |
09 Nov 2004 06:06:00 PM |
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(William J. Beaty) wrote in message news:<2251b4e6.0411022131.397e3733@posting.google.com>...
Gravity field of a photon.
You'd be taken a bit more serious if you
posted topically. How much GR do you know,
or want to?
Ken
1.
Suppose we launch a light pulse with a ridiculously powerful
laser. The pulse is a few cm across, a nS long, and has enough
energy that by E=MC^2 it weighs as much as a large asteroid. Will
this travelling light-pulse have its own gravity field? And, since
it's moving at C, won't it create a cone-shaped shock wave of
gravity (so we'd feel a big "thud" as the pulse flew past?)
2.
Instead let's put some extremely bright light into a small box with
100% reflecting walls. If the light is so bright that, as before,
it weighs as much as a large asteroid, won't the box have its own
gravity field? (Can a box full of energy NOT have mass?!!) Won't
the light within the box significantly attract the light in a nearby
similar box, so the two boxes fall together? And if we keep adding
more light, won't it eventually condense gravitationally, forming an
event horizon that scavenges up all the light in the box, so we can
safely open the lid and look inside without singing our eyebrows?
3.
Do individual photons have very weak gravitational shock waves?
Suppose we had a high frequency light source where the photon
energy was so large that individual photons could have measurable
gravity effects. Does a flying photon have a gravity field?
And what happens if this photon enters our 100% reflective box and
starts bouncing around inside? Does the box wiggle? Or does it
start emitting gravity waves?
((((((((((((((((((((((( ( ( (o) ) ) )))))))))))))))))))))))
William J. Beaty Research Engineer
beaty@chem.washington.edu UW Chem Dept, Bagley Hall RM74
Box 351700, Seattle, WA 98195-1700
ph206-543-6195 http//staff.washington.edu/wbeaty/
.
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| User: "William J. Beaty" |
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| Title: Re: Mr. Tompkins spreads viagra on his laser |
12 Nov 2004 08:07:51 PM |
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(Ken S. Tucker) wrote in message news:<2202379a.0411091606.7bf8ab01@posting.google.com>...
billb@eskimo.com (William J. Beaty) wrote in message news:<2251b4e6.0411022131.397e3733@posting.google.com>...
Gravity field of a photon.
You'd be taken a bit more serious if you
posted topically.
Ken
The thought-experiment was somewhat ridiculous, therefore it needed
an appropriate subject line!
(But do users have usenet spamblocking which will render this entire
thread invisible? The nine billion names of veeeeaaaagrra.)
How much GR do you know, or want to?
I operate at the popular-book, Michio-Kaku Paul-Davies level. I came up
with the gedanken experiments below in order to clarify a few interlocking
issues about which I've been wondering.
So, photons DON'T follow E=MC^2? I thought photons were supposed
to have zero REST MASS, rather than no mass whatsoever. And I was
under the impression that mass-energy equivalence applied always, i.e.
any volume which contains energy must also contain mass, and therefore
must exert a force or bend the trajectories of distant masses. In
other words, if a star can alter the trajectory of a light beam, then
a light beam can (slightly) alter the trajectory of a star. To
highlight the issue, I chose to use an optical pulse which is intense
enough that it would create easily measurable gravity attraction, if
it had any.
1.
Suppose we launch a light pulse with a ridiculously powerful
laser. The pulse is a few cm across, a nS long, and has enough
energy that by E=MC^2 it weighs as much as a large asteroid. Will
this travelling light-pulse have its own gravity field? And, since
it's moving at C, won't it create a cone-shaped shock wave of
gravity (so we'd feel a big "thud" as the pulse flew past?)
2.
Instead let's put some extremely bright light into a small box with
100% reflecting walls. If the light is so bright that, as before,
it weighs as much as a large asteroid, won't the box have its own
gravity field? (Can a box full of energy NOT have mass?!!) Won't
the light within the box significantly attract the light in a nearby
similar box, so the two boxes fall together? And if we keep adding
more light, won't it eventually condense gravitationally, forming an
event horizon that scavenges up all the light in the box, so we can
safely open the lid and look inside without singing our eyebrows?
3.
Do individual photons have very weak gravitational shock waves?
Suppose we had a high frequency light source where the photon
energy was so large that individual photons could have measurable
gravity effects. Does a flying photon have a gravity field?
And what happens if this photon enters our 100% reflective box and
starts bouncing around inside? Does the box wiggle? Or does it
start emitting gravity waves?
((((((((((((((((((((((( ( ( (o) ) ) )))))))))))))))))))))))
William J. Beaty Research Engineer
beaty@chem.washington.edu UW Chem Dept, Bagley Hall RM74
billb@eskimo.com Box 351700, Seattle, WA 98195-1700
ph206-543-6195 http//staff.washington.edu/wbeaty/
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| User: "Mark Fergerson" |
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| Title: Re: Mr. Tompkins spreads viagra on his laser |
10 Nov 2004 08:43:13 AM |
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Ken S. Tucker wrote:
billb@eskimo.com (William J. Beaty) wrote in message news:<2251b4e6.0411022131.397e3733@posting.google.com>...
Gravity field of a photon.
You'd be taken a bit more serious if you
posted topically. How much GR do you know,
or want to?
Look through his site. Mr. Beaty is my favorite kind of
raving lunatic; the kind that comes up with actual physical
examples of his ravings, proving physics can be fun.
Mark L. Fergerson
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| User: "Ken S. Tucker" |
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| Title: Re: Mr. Tompkins spreads viagra on his laser |
11 Nov 2004 12:00:32 AM |
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Mark Fergerson <nunya@biz.ness> wrote in message news:<qMpkd.51594$G15.50212@fed1read03>...
Ken S. Tucker wrote:
billb@eskimo.com (William J. Beaty) wrote in message news:<2251b4e6.0411022131.397e3733@posting.google.com>...
Gravity field of a photon.
You'd be taken a bit more serious if you
posted topically. How much GR do you know,
or want to?
Look through his site. Mr. Beaty is my favorite kind of
raving lunatic; the kind that comes up with actual physical
examples of his ravings, proving physics can be fun.
Mark L. Fergerson
Thanks Mark,
His questions are good, but the answer is difficult.
For example it involves why light is deflected at
twice the rate that Newton theory predicts.
So I'd need to get the OP up to speed on space warps
(g11...g33) prior to even beginning to answer.
That's a worthwhile engagemant provided the OP
is serious, that's what I mean.
Ken
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| User: "William J. Beaty" |
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| Title: Re: Mr. Tompkins spreads viagra on his laser |
12 Nov 2004 09:20:19 PM |
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(Ken S. Tucker) wrote in message news:<2202379a.0411102200.5486587f@posting.google.com>...
His questions are good, but the answer is difficult.
For example it involves why light is deflected at
twice the rate that Newton theory predicts.
That's not an answer, that's a full explanation. Initially I'm not
asking for the details of *why* GR would give particular answers, I'm
asking questions along the lines of "what would happen if..."
Well, what WOULD happen?
But I reserve the right to ask further simple questions to remove any
distractions from the core concepts. For example, with light in a box,
if the box acts as a spring, it possibly gains mass when storing
potential energy. So let's remove the box: let's confine the light by
letting a dense object bend the light into a closed path. In detail:
Is it possible to make mass appear and vanish? If I convert the
star Betelguese into a beam of light, has mass vanished from the
universe? If I then force that light-beam to bend into a circle
(use a small black hole) will the original mass of Betelguese have
added to the black hole mass?
((((((((((((((((((((((( ( ( (o) ) ) )))))))))))))))))))))))
William J. Beaty Research Engineer
beaty@chem.washington.edu UW Chem Dept, Bagley Hall RM74
billb@eskimo.com Box 351700, Seattle, WA 98195-1700
ph206-543-6195 http//staff.washington.edu/wbeaty/
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| User: "Mark Fergerson" |
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| Title: Re: Mr. Tompkins spreads viagra on his laser |
11 Nov 2004 12:17:02 AM |
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Ken S. Tucker wrote:
Mark Fergerson <nunya@biz.ness> wrote in message news:<qMpkd.51594$G15.50212@fed1read03>...
Ken S. Tucker wrote:
billb@eskimo.com (William J. Beaty) wrote in message news:<2251b4e6.0411022131.397e3733@posting.google.com>...
Gravity field of a photon.
You'd be taken a bit more serious if you
posted topically. How much GR do you know,
or want to?
Look through his site. Mr. Beaty is my favorite kind of
raving lunatic; the kind that comes up with actual physical
examples of his ravings, proving physics can be fun.
Thanks Mark,
His questions are good, but the answer is difficult.
For example it involves why light is deflected at
twice the rate that Newton theory predicts.
So I'd need to get the OP up to speed on space warps
(g11...g33) prior to even beginning to answer.
That's a worthwhile engagemant provided the OP
is serious, that's what I mean.
He's just looking for encouragement fooling with
overpowered lasers etc. Give him half an excuse and he'll
try to detect the "mass" of a laser beam. Hell, he might
succeed. ;>)
Mark L. Fergerson
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| User: "William J. Beaty" |
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| Title: Re: Mr. Tompkins spreads viagra on his laser |
12 Nov 2004 09:23:00 PM |
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Mark Fergerson <nunya@biz.ness> wrote in message news:<SrDkd.53276$G15.19433@fed1read03>...
He's just looking for encouragement fooling with
overpowered lasers etc. Give him half an excuse and he'll
try to detect the "mass" of a laser beam. Hell, he might
succeed. ;>)
I was thinking along the lines of a microwave oven with a really
really really powerful magnetron.
:)
It could melt beer bottles even if the beer bottles were made
out of white dwarf matter.
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| User: "Wayne Shanks" |
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| Title: Re: Mr. Tompkins spreads viagra on his laser |
09 Nov 2004 02:02:40 AM |
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Hey Bill
William J. Beaty wrote:
Gravity field of a photon.
1.
Suppose we launch a light pulse with a ridiculously powerful
laser. The pulse is a few cm across, a nS long, and has enough
energy that by E=MC^2 it weighs as much as a large asteroid. Will
this travelling light-pulse have its own gravity field? And, since
it's moving at C, won't it create a cone-shaped shock wave of
gravity (so we'd feel a big "thud" as the pulse flew past?)
Photons have no mass, thus no gravity shock.... if they did, then the
energy of the photon would be radiated away as gravitons... as you put
in, in the gravitational shock.... but all this is academic, and photons
do not warp space time
2.
Instead let's put some extremely bright light into a small box with
100% reflecting walls. If the light is so bright that, as before,
it weighs as much as a large asteroid, won't the box have its own
gravity field? (Can a box full of energy NOT have mass?!!)
Hmmmmm, the box will experience a far greater outward pressure caused by
the photon gas within the box. Can the box have mass associated
with the stored energy within?... light trapped within the box must
exist in some collection of boson stationary "particle in a box" states.
Does an excited electromagnetic cavity have mass associated with
the stored energy? I do not know... I bet not.... the box is like a
compressed spring..... the mass defect in nuclear reactions is actually
just electrostatic potential energy ( also like a compressed spring)....
Won't
the light within the box significantly attract the light in a nearby
similar box, so the two boxes fall together? And if we keep adding
more light, won't it eventually condense gravitationally, forming an
event horizon that scavenges up all the light in the box, so we can
safely open the lid and look inside without singing our eyebrows?
I have never heard of graviton mediated photon-photon scattering.
Note that for high enough photon energy you can get electron positron
pair production, which would have mass. I have heard of high energy
photon photon scattering where scattering is mediated by virtual pair
production and scattering. The probability of this form of scattering
drops quickly as photon energy drops below pair production energies, but
a google of low energy photons may have a non trivial self
interaction. I remember some other photon - photon interactions, but
they are smalllllllllllllllllllllllll.
3.
Do individual photons have very weak gravitational shock waves?
Suppose we had a high frequency light source where the photon
energy was so large that individual photons could have measurable
gravity effects. Does a flying photon have a gravity field?
And what happens if this photon enters our 100% reflective box and
starts bouncing around inside? Does the box wiggle? Or does it
start emitting gravity waves?
We can see some very old photons, so that tells us there is no
gravitational shock for photons... or is is VERY VERY VERY VERY (lots
more VERYs) small
Wayne S
((((((((((((((((((((((( ( ( (o) ) ) )))))))))))))))))))))))
William J. Beaty Research Engineer
beaty@chem.washington.edu UW Chem Dept, Bagley Hall RM74
billb@eskimo.com Box 351700, Seattle, WA 98195-1700
ph206-543-6195 http//staff.washington.edu/wbeaty/
--
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| User: "William J. Beaty" |
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| Title: Re: Mr. Tompkins spreads viagra on his laser |
12 Nov 2004 08:42:03 PM |
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Wayne Shanks <wshanks@charm.net.nospam> wrote in message news:<JJ_jd.12$iv2.6142@news.abs.net>...
2.
Instead let's put some extremely bright light into a small box with
100% reflecting walls. If the light is so bright that, as before,
it weighs as much as a large asteroid, won't the box have its own
gravity field? (Can a box full of energy NOT have mass?!!)
Hmmmmm, the box will experience a far greater outward pressure caused by
the photon gas within the box. Can the box have mass associated
with the stored energy within?... light trapped within the box must
exist in some collection of boson stationary "particle in a box" states.
That might be the explanation: unconstrained light doesn't attract
distant masses, but at the instant that the lid is closed on the
box, will the system comprised of light+box suddenly begin to warp
space? (So, in theory, we could produce gravity waves rather than by
shaking a boson around, instead by suddenly placing constraints on an
optical pulse, then suddenly removing them?
Does an excited electromagnetic cavity have mass associated with
the stored energy? I do not know... I bet not.... the box is like a
compressed spring..... the mass defect in nuclear reactions is actually
just electrostatic potential energy ( also like a compressed spring)....
Hmmm, the compressed spring might offer the explanation. But then I'm forced
to ask about the time-course of the spring. Suppose I SUDDENLY shatter the
box. For a few nanoseconds the photon cloud will remain fairly small.
Does the box-light system suddenly stop attracting distant masses? Oh,
but the change in gravity would propagate outwards along with the expanding
sphere of light. Um... OK, let the photons propagate away from the
suddenly-opened box as a pair of collimated beams going in opposite
directions. When all is said and done, won't it appear that a large mass
has suddenly winked out of existence? And as before, doesn't having
"E" without "M" violate the equivalence principle? Or can there be a
special kind of mass which satisfies E=MC^2 but without attracting
distant masses?
Exploring a similar idea: suppose we have some tera-KG worth of electrons
and positrons. Imagine them to be cold positronium atoms, if you wish.
They'll attract distant masses, right? Gravity-wise, what happens when
they decay? When converted into gammas, do they stop attracting distant
masses? Or in other words, whenever an electron and positron
anihilate, does the mass of the system change?
I have never heard of graviton mediated photon-photon scattering.
Note that for high enough photon energy you can get electron positron
pair production, which would have mass.
But I'm wondering about the E-MC^2 mass of a light-pulse. If that
light pulse is supposed to have zero mass, then the mass arising from
electrons/positrons would be a separate issue. Or is there a solid
link between the concepts? If light is required to have mass because
of E=MC^2, is that mass contained in the low-probability electrons/
positrons that are appearing?
I have heard of high energy
photon photon scattering where scattering is mediated by virtual pair
production and scattering. The probability of this form of scattering
drops quickly as photon energy drops below pair production energies, but
a google of low energy photons may have a non trivial self
interaction. I remember some other photon - photon interactions, but
they are smalllllllllllllllllllllllll.
Don't forget that I'm talking about taking a gigaton asteroid and
converting it into an optical pulse. The energy density is fairly
high.
((((((((((((((((((((((( ( ( (o) ) ) )))))))))))))))))))))))
William J. Beaty Research Engineer
beaty@chem.washington.edu UW Chem Dept, Bagley Hall RM74
billb@eskimo.com Box 351700, Seattle, WA 98195-1700
ph206-543-6195 http//staff.washington.edu/wbeaty/
.
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| User: "FrediFizzx" |
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| Title: Re: Mr. Tompkins spreads viagra on his laser |
13 Nov 2004 12:56:54 PM |
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"William J. Beaty" <billb@eskimo.com> wrote in message
news:2251b4e6.0411121842.5f8b78b1@posting.google.com...
| Wayne Shanks <wshanks@charm.net.nospam> wrote in message
news:<JJ_jd.12$iv2.6142@news.abs.net>...
|
| > > 2.
| > > Instead let's put some extremely bright light into a small box with
| > > 100% reflecting walls. If the light is so bright that, as before,
| > > it weighs as much as a large asteroid, won't the box have its own
| > > gravity field? (Can a box full of energy NOT have mass?!!)
| >
| > Hmmmmm, the box will experience a far greater outward pressure caused by
| > the photon gas within the box. Can the box have mass associated
| > with the stored energy within?... light trapped within the box must
| > exist in some collection of boson stationary "particle in a box" states.
|
| That might be the explanation: unconstrained light doesn't attract
| distant masses, but at the instant that the lid is closed on the
| box, will the system comprised of light+box suddenly begin to warp
| space? (So, in theory, we could produce gravity waves rather than by
| shaking a boson around, instead by suddenly placing constraints on an
| optical pulse, then suddenly removing them?
|
|
| > Does an excited electromagnetic cavity have mass associated with
| > the stored energy? I do not know... I bet not.... the box is like a
| > compressed spring..... the mass defect in nuclear reactions is actually
| > just electrostatic potential energy ( also like a compressed spring)....
|
|
| Hmmm, the compressed spring might offer the explanation. But then I'm
forced
| to ask about the time-course of the spring. Suppose I SUDDENLY shatter
the
| box. For a few nanoseconds the photon cloud will remain fairly small.
| Does the box-light system suddenly stop attracting distant masses? Oh,
| but the change in gravity would propagate outwards along with the
expanding
| sphere of light. Um... OK, let the photons propagate away from the
| suddenly-opened box as a pair of collimated beams going in opposite
| directions. When all is said and done, won't it appear that a large mass
| has suddenly winked out of existence? And as before, doesn't having
| "E" without "M" violate the equivalence principle? Or can there be a
| special kind of mass which satisfies E=MC^2 but without attracting
| distant masses?
Since the strength of gravity is about 40 orders of magnitude less than EM,
the gravity wave would be masked by the EM wave.
| Exploring a similar idea: suppose we have some tera-KG worth of electrons
| and positrons. Imagine them to be cold positronium atoms, if you wish.
| They'll attract distant masses, right? Gravity-wise, what happens when
| they decay? When converted into gammas, do they stop attracting distant
| masses? Or in other words, whenever an electron and positron
| anihilate, does the mass of the system change?
The mass of the "system" does not change other than being converted to what
I would call impractical mass. If the annihilation produces two photons,
then as a system, those two photons have mass equal to 2*m_e plus any
kinetic energy the electron and positron had. Destroy one of the photons,
then the system is broken so to speak. A single photon does not have mass
but a system of photons can.
| > I have never heard of graviton mediated photon-photon scattering.
| >
| > Note that for high enough photon energy you can get electron positron
| > pair production, which would have mass.
|
| But I'm wondering about the E-MC^2 mass of a light-pulse. If that
| light pulse is supposed to have zero mass, then the mass arising from
| electrons/positrons would be a separate issue. Or is there a solid
| link between the concepts? If light is required to have mass because
| of E=MC^2, is that mass contained in the low-probability electrons/
| positrons that are appearing?
A light pulse follows E = pc, not E = mc^2.
| > I have heard of high energy
| > photon photon scattering where scattering is mediated by virtual pair
| > production and scattering. The probability of this form of scattering
| > drops quickly as photon energy drops below pair production energies, but
| > a google of low energy photons may have a non trivial self
| > interaction. I remember some other photon - photon interactions, but
| > they are smalllllllllllllllllllllllll.
|
| Don't forget that I'm talking about taking a gigaton asteroid and
| converting it into an optical pulse. The energy density is fairly
| high.
I hardly think it would be "optical".
FrediFizzx
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