Interstellar Propulsion idea using an Asteroid and a few comets!

Hi John,

I'm sorry I was speaking from ignorance, about the energy of a graviton.
Clearly I was wrong on that.

Still, now again I am utterly confused about gravitons, and gravity.
If gravitons dont occur very often, they could not cause the space-time
curvature which is responsible for gravity. So, what is ?

Rob

"John Thingstad" wrote in message
news
On Wed, 01 Sep 2004 08:58:17 GMT, Rob Dekker wrote:


But hard proof either way is still is not there...we have not observed
gravitons as particles (in some quantum effect), because their energy
is so
absurtly small, so we cant measure their speed directly...


Actually you got it exactly wrong. The particles move throgh a Higgs
field.
The mass of the particle is inversely proportional to the strength of the
force. So a graviton is in fact the most massive particle there is.
To accelerate a particle to get enough energy to produce graviton's
you would need a 1 light year long accelerator.
So their energy is positively huge.
The idea behind this is that in any energy field virtual particles are
continuously
produced due to the fact that space contains energy. Since the amount of
energy needed to create a graviton is very high the chance of one being
produced is very small.

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On Wed, 08 Sep 2004 09:38:55 GMT, Rob Dekker wrote:


Still, now again I am utterly confused about gravitons, and gravity.
If gravitons dont occur very often, they could not cause the space-time
curvature which is responsible for gravity. So, what is ?


Sigh. Join the club!
If you can find a scientist who isn't let me know..
Many, like me, doubt the existence of the graviton all together. (Penrose
et al)
Obviously, assuming gravitons exist, the curvature notion only exists on
the macro scale.
It will break down at plank scale.
It get's worse. In special relativity mass will increase rapidly when you
get
very close to the speed of light (top percent).
If you get close enough the gravity becomes so great that the ship would
collape
and become a star. (The number of gravitons created increases rapidly too.)
What gives me the trouble with it is that special relativity is integrated
into quantum physics
to become quantum field theory (Paul Dirac). Here it is the property of
the field.
Gravity however is produced by the exchange of gravitons which happens to
produce a force of
exactly the same proportion. (I have trouble with coincedences.)

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"John Thingstad" wrote:

It get's worse. In special relativity mass will increase rapidly when you
get
very close to the speed of light (top percent).
If you get close enough the gravity becomes so great that the ship would
collape
and become a star.

No. Mass does not depend on speed; it is the same no matter which
reference frame you measure in. If it were otherwise, you could have odd
situations where an object is a black hole for some observers and not for
others.

Traveling near the speed of light will not cause a spaceship to collapse
under its own gravity.

"Rob Dekker" wrote in message
. com...
Hi John,

I'm sorry I was speaking from ignorance, about the energy of a graviton.
Clearly I was wrong on that.

Still, now again I am utterly confused about gravitons, and gravity.
If gravitons dont occur very often, they could not cause the space-time
curvature which is responsible for gravity. So, what is ?

Mass causes the curvature of space ... the degree of bending (of distortion)
is proportional to the mass of the object ...

It generally takes huge changes in/of mass to cause gravitational waves.
Siesmic activity on the surface of a neutron star or pulsar can cause
gravitational waves to be emitted. Close binary neutron stars will also emit
gravitational waves. There are scientific projects right now searching for
signs of gravity waves. See:
http://arxiv.org/PS_cache/physics/pdf/9908/9908041.pdf
Al



Rob

"John Thingstad" wrote in message
news
On Wed, 01 Sep 2004 08:58:17 GMT, Rob Dekker wrote:


But hard proof either way is still is not there...we have not observed
gravitons as particles (in some quantum effect), because their energy
is so
absurtly small, so we cant measure their speed directly...


Actually you got it exactly wrong. The particles move throgh a Higgs
field.
The mass of the particle is inversely proportional to the strength of
the
force. So a graviton is in fact the most massive particle there is.
To accelerate a particle to get enough energy to produce graviton's
you would need a 1 light year long accelerator.
So their energy is positively huge.
The idea behind this is that in any energy field virtual particles are
continuously
produced due to the fact that space contains energy. Since the amount of
energy needed to create a graviton is very high the chance of one being
produced is very small.

--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

Look at the LIGO experiment web site too:
http://www.ligo.caltech.edu/LIGO_web...pts/facts.html
Al


"Rob Dekker" wrote in message
. com...
Hi John,

I'm sorry I was speaking from ignorance, about the energy of a graviton.
Clearly I was wrong on that.

Still, now again I am utterly confused about gravitons, and gravity.
If gravitons dont occur very often, they could not cause the space-time
curvature which is responsible for gravity. So, what is ?

Rob

"John Thingstad" wrote in message
news
On Wed, 01 Sep 2004 08:58:17 GMT, Rob Dekker wrote:


But hard proof either way is still is not there...we have not observed
gravitons as particles (in some quantum effect), because their energy
is so
absurtly small, so we cant measure their speed directly...


Actually you got it exactly wrong. The particles move throgh a Higgs
field.
The mass of the particle is inversely proportional to the strength of
the
force. So a graviton is in fact the most massive particle there is.
To accelerate a particle to get enough energy to produce graviton's
you would need a 1 light year long accelerator.
So their energy is positively huge.
The idea behind this is that in any energy field virtual particles are
continuously
produced due to the fact that space contains energy. Since the amount of
energy needed to create a graviton is very high the chance of one being
produced is very small.

--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

Rob,

At Wednesday 08 September 2004 02:38 in sci.astro.seti Rob Dekker wrote:

Hi John,

I'm sorry I was speaking from ignorance, about the energy of a graviton.
Clearly I was wrong on that.

Still, now again I am utterly confused about gravitons, and gravity.
If gravitons dont occur very often, they could not cause the space-time
curvature which is responsible for gravity. So, what is ?

The universe is drenched with gravitons. From the very moment the diameter
of the universe became non-zero, their number has been increasing. They
are exchanged between all pairs of massive particles that are within each
other's mutual light horizon. They have no rest mass, of course, and
travel at the speed of light.

At least that's how I understand them.

By the way, I find the transactional interpretation of QM put forth by
John G. Cramer to be a helpful and intriguing way to think about photons
and gravitons. See
http://www.npl.washington.edu/npl/int_rep/tiqm/TI_toc.html for
starters. Or maybe this one for starters:
http://www.npl.washington.edu/AV/altvw16.html

Randall Schulz

After some more reading, I'm still not convinced that gravitons are so massive
as you suggest... Here is an interesting observation :
http://www.iop.org/EJ/abstract/0264-9381/19/7/318/

In summary : "..mass of the graviton to be less than 7.6 × 10-20 eV/c2 at 90% confidence"

And I was not talking about mass. I was talking about energy.

Rob

"John Thingstad" wrote in message news
On Wed, 01 Sep 2004 08:58:17 GMT, Rob Dekker wrote:


But hard proof either way is still is not there...we have not observed
gravitons as particles (in some quantum effect), because their energy
is so
absurtly small, so we cant measure their speed directly...


Actually you got it exactly wrong. The particles move throgh a Higgs field.
The mass of the particle is inversely proportional to the strength of the
force. So a graviton is in fact the most massive particle there is.
To accelerate a particle to get enough energy to produce graviton's
you would need a 1 light year long accelerator.
So their energy is positively huge.
The idea behind this is that in any energy field virtual particles are
continuously
produced due to the fact that space contains energy. Since the amount of
energy needed to create a graviton is very high the chance of one being
produced is very small.

--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

"RD" == Rob Dekker writes:

RD "John Thingstad" wrote in message
RD news
On Wed, 01 Sep 2004 08:58:17 GMT, Rob Dekker wrote:

we have not observed gravitons as particles (...), because their
energy is so absurtly small, so we cant measure their speed
directly...

Actually you got it exactly wrong. The particles move throgh a
Higgs field. The mass of the particle is inversely proportional to
the strength of the force. So a graviton is in fact the most
massive particle there is. To accelerate a particle to get enough
energy to produce graviton's you would need a 1 light year long
accelerator. So their energy is positively huge. The idea behind
this is that in any energy field virtual particles are continuously
produced due to the fact that space contains energy. Since the
amount of energy needed to create a graviton is very high the
chance of one being produced is very small.

RD After some more reading, I'm still not convinced that gravitons
RD are so massive as you suggest... Here is an interesting
RD observation :
RD http://www.iop.org/EJ/abstract/0264-9381/19/7/318/

RD In summary : "..mass of the graviton to be less than 7.6 x 10^-20
RD eV/c2 at 90% confidence"

There's another good reason to expect the graviton to be massless:
That's the only way to get a 1/r^2 law. The W and Z bosons, which
mediate the weak force, are massive and the weak force is consequently
quite short range.

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