speed of gravity

[PolymerTim]

That's interesting to hear about the pi orbital effect; I hadn't heard about that. I had heard that refractive index is based, in part, on density as well, but I never knew what any other "chemical" factors were. In fact the density effect is the principle behind a detector I use that measures change in refractive index and correlates this linearly with solution concentration in a liquid chromatography setup.

The detail I was trying to figure out based on my last response was if the speed of light in a medium is slower on all length scales. My guess was that the "effective" speed I have seen referred to the apparent speed over lengths larger than, say, a micrometer (I imagine we can't actually measure it over that small a distance any way). But I was wondering if maybe the photons, on a sub angstrom level, kind of skip from one atom to the next at c_o, but then get caught for some time at an atom before moving on to the next one. I now see that's probably wrong though since, if it is actually the electron cloud that is interacting with photons, then I imagine the photons are practically travelling through a sea of them and are probably going a near constant speed even on the sub-angstrom length scale, subject primarily to density fluctuations.

 

[silverpig]

Originally posted by: PolymerTim
That's interesting to hear about the pi orbital effect; I hadn't heard about that. I had heard that refractive index is based, in part, on density as well, but I never knew what any other "chemical" factors were. In fact the density effect is the principle behind a detector I use that measures change in refractive index and correlates this linearly with solution concentration in a liquid chromatography setup.

The detail I was trying to figure out based on my last response was if the speed of light in a medium is slower on all length scales. My guess was that the "effective" speed I have seen referred to the apparent speed over lengths larger than, say, a micrometer (I imagine we can't actually measure it over that small a distance any way). But I was wondering if maybe the photons, on a sub angstrom level, kind of skip from one atom to the next at c_o, but then get caught for some time at an atom before moving on to the next one. I now see that's probably wrong though since, if it is actually the electron cloud that is interacting with photons, then I imagine the photons are practically travelling through a sea of them and are probably going a near constant speed even on the sub-angstrom length scale, subject primarily to density fluctuations.

I routinely see the change of optical path length over .34 nm (single atomic sheets). It can be calculated, measured, and seen.

 

[hellokeith]

Update March 1, 2008

Space.com - "Pioneer anomaly" reers its ugly head again, defies current gravity models

NASA Baffled by Unexplained Force Acting on Space Probes
By Charles Q. Choi
Special to SPACE.com
posted: 29 February 2008

Mysteriously, five spacecraft that flew past the Earth have each displayed unexpected anomalies in their motions.

These newfound enigmas join the so-called "Pioneer anomaly" as hints that unexplained forces may appear to act on spacecraft.

A decade ago, after rigorous analyses, anomalies were seen with the identical Pioneer 10 and 11 spacecraft as they hurtled out of the solar system. Both seemed to experience a tiny but unexplained constant acceleration toward the sun.

A host of explanations have been bandied about for the Pioneer anomaly. At times these are rooted in conventional science ? perhaps leaks from the spacecraft have affected their trajectories. At times these are rooted in more speculative physics ? maybe the law of gravity itself needs to be modified.

Now Jet Propulsion Laboratory astronomer John Anderson and his colleagues ? who originally helped uncover the Pioneer anomaly ? have discovered that five spacecraft each raced either a tiny bit faster or slower than expected when they flew past the Earth en route to other parts of the solar system.

A constant unaccounted-for acceleration towards the sun or other massive body could easily be explained by gravity having a propogation speed > c. I'm not saying it's necessarily instantaneous, but entirely possible gravity attracts at many times faster than light speed.

 

[PlasmaBomb]

Since we are back on to gravity, and all like computers -
http://www.reghardware.co.uk/2...simulating_blackholes/
http://gravity.phy.umassd.edu/ps3.html

 

[DrPizza]

Originally posted by: Born2bwire
However, c is still the speed limit in this case. That is, irregardless (that's right, I said that wrong) of the environment, information cannot propagate faster than c, though this does not mean that light can only travel at c.

I'm not entirely sure that's true either. I recall reading about ultra dense states of matter where sound could travel faster than light. (I'm not sure if it was only theoretical though)

However, google Cerenkov radiation. That's a case where particles are traveling faster than the speed of light through a medium.

 

[f95toli]

Originally posted by: DrPizza

I'm not entirely sure that's true either. I recall reading about ultra dense states of matter where sound could travel faster than light. (I'm not sure if it was only theoretical though)

Well, there is nothing preventing us from creating a material where sounds travels faster than the speed of light in that medium. But it is NOT possible to create a material where the speed of sound is greated than the speed of light in vacuum.

 

[Nathelion]

Originally posted by: Gannon

Originally posted by: firewolfsm
I think the easiest way to explain that is that light may be slowed down in water, glass, air or whatever, but other things, like gravity, nuetrinos, etc. will still travel at c, as we know it in a vacuum.

What I'm curious about is if you stretch space-time/fold it technically you should be able to make light get to places technically faster in the sense that you'd have space-time stretched in certain places but not others, even though no law was violated.

Imagine you have a series of 'c travel dots' (just to make this easy) on a rubber band of space time, and say this rubber band is capable of being significantly stretched without breaking, etc, each of 'c those travel dots' would would be stretched so technically light would travel at c along the surface but the 'legal' travel positions where light exists would technically be spaced farther apart.

According to einstein reality is one continuous field, there are no 'objects' as such

"Since the theory of general relatively implies the representation of physical reality by a continuous field, the concept of particles or material points cannot play a fundamental part, ... and can only appear as a limited region in space where the field strength / energy density are particularly high. (Albert Einstein, 1950) "

This would mean that particles are not truly 'fundamental'. since they are artifacts of strong fields, of some deeper non particle reality.

Perceiving propagation at 'speeds' may be a little strange even when we think about it since we are really refering to space-time relationships, and interactions of light with matter would not be interactions 'with matter' but with a field that is significantly strong and whos field effects space-time in such a way as to cause light to 'slow down'.

Look at the wikipedia entry for Alcubierre space drive. It is based on this exact idea.
Supposedly, it would require all the energy in the universe to make it happen And there is, as far as we know, no way to actually stop once youve got it working. So the usefulness of that particular construct may be somewhat... limited

While you are at it, google "inflation theory"

 

[PolymerTim]

Originally posted by: silverpig
I routinely see the change of optical path length over .34 nm (single atomic sheets). It can be calculated, measured, and seen.

That's awesome, I didn't know that! What is the technique called? I'm guessing some kind of light scattering? I'd like to read up on that.

 

[silverpig]

Originally posted by: PolymerTim

Originally posted by: silverpig
I routinely see the change of optical path length over .34 nm (single atomic sheets). It can be calculated, measured, and seen.

That's awesome, I didn't know that! What is the technique called? I'm guessing some kind of light scattering? I'd like to read up on that.

Uh, looking through an optical microscope? Google for some papers about graphene and the technique should be explained. Basically you put a piece of graphite on a piece of scotch tape, fold it sticky side to sticky side an pull it apart. You've roughly cleaved the graphite chunk in half. Repeat several times (~30 or so), then stick the graphite covered tape to a silicon wafer with a 300 nm SiO2 layer grown on top. The SiO2 makes the wafer look purple at that thickness and some interference condition is set up whereby the optical path length of a green photon travelling through the graphene, SiO2, reflecting off the Si, then making the return trip is N+1/2 times longer than just reflecting off the graphene (I'm not 100% sure this is correct, but it's the gist of it). The upshot is you can see the difference in colour between the bare SiO2 and the graphene covered SiO2 just using a white light optical microscope.

This is now a huge area of research

Here's a picture.

 

[RideFree]

Originally posted by: silverpig
This is now a huge area of research

Here's a picture.

There's a lot left to be discovered in this{sic} universe.

We're all probably searching for the truth in one way or another.

 

[Born2bwire]

Originally posted by: silverpig

Originally posted by: PolymerTim

Originally posted by: silverpig
I routinely see the change of optical path length over .34 nm (single atomic sheets). It can be calculated, measured, and seen.

That's awesome, I didn't know that! What is the technique called? I'm guessing some kind of light scattering? I'd like to read up on that.

Uh, looking through an optical microscope? Google for some papers about graphene and the technique should be explained. Basically you put a piece of graphite on a piece of scotch tape, fold it sticky side to sticky side an pull it apart. You've roughly cleaved the graphite chunk in half. Repeat several times (~30 or so), then stick the graphite covered tape to a silicon wafer with a 300 nm SiO2 layer grown on top. The SiO2 makes the wafer look purple at that thickness and some interference condition is set up whereby the optical path length of a green photon travelling through the graphene, SiO2, reflecting off the Si, then making the return trip is N+1/2 times longer than just reflecting off the graphene (I'm not 100% sure this is correct, but it's the gist of it). The upshot is you can see the difference in colour between the bare SiO2 and the graphene covered SiO2 just using a white light optical microscope.

This is now a huge area of research

Here's a picture.

What really interests me is that I sat in on a presentation about how a single graphene sheet can support a traveling EM wave. Would be very interesting to see if they could create graphene transmission lines.

 

[silverpig]

Originally posted by: Born2bwire

Originally posted by: silverpig

Originally posted by: PolymerTim

Originally posted by: silverpig
I routinely see the change of optical path length over .34 nm (single atomic sheets). It can be calculated, measured, and seen.

That's awesome, I didn't know that! What is the technique called? I'm guessing some kind of light scattering? I'd like to read up on that.

Uh, looking through an optical microscope? Google for some papers about graphene and the technique should be explained. Basically you put a piece of graphite on a piece of scotch tape, fold it sticky side to sticky side an pull it apart. You've roughly cleaved the graphite chunk in half. Repeat several times (~30 or so), then stick the graphite covered tape to a silicon wafer with a 300 nm SiO2 layer grown on top. The SiO2 makes the wafer look purple at that thickness and some interference condition is set up whereby the optical path length of a green photon travelling through the graphene, SiO2, reflecting off the Si, then making the return trip is N+1/2 times longer than just reflecting off the graphene (I'm not 100% sure this is correct, but it's the gist of it). The upshot is you can see the difference in colour between the bare SiO2 and the graphene covered SiO2 just using a white light optical microscope.

This is now a huge area of research

Here's a picture.

What really interests me is that I sat in on a presentation about how a single graphene sheet can support a traveling EM wave. Would be very interesting to see if they could create graphene transmission lines.

Well we can attach leads to graphene and it has all sorts of wonderful properties. The first is that it's a 0-gap semiconductor with a relativistic dispersion relation. That basically means the charge carriers act like massless dirac fermions (ie like photons but with spin 1/2) with an intrinsic "speed of light" of about c/300. This gives it a peculiar quantum hall effect, it's an excellent conductor, offers much higher mobility than other semiconductors... If only we could figure out a way of growing a full contiguous monolayer on a wafer.

 

[RideFree]

Alex Mayer, "A testable solution to the problem of quantum gravity"


Latest from Dr. Mayer.

Also, don't dare miss the enthralling controversy at Dr Mayer's on-line site.
Good place to start is papers and make sure you follow links at the bottom.
Google is even involved! I've also had my own share of dealings with Google...

(Alex received the following via e-mail on 2 Feb. ?08)

[ Alex, ]

Considering the amount of money, the magnitude of people?s programs, status and security plus the political budgets and connections invested in the structure you are threatening to dismantle, I expect you to be ignored so long as possible and when that becomes difficult, attacked in some very unpleasant ways. Being correct about your subject will remain irrelevant, perhaps for most or even all of your lifetime unless you are either lucky or able to line up some fully committed support strong enough that it can?t be pushed around. Your best ally will probably be the internet and its bloggers. Like all rapacious beasts though, they will require careful and continuing feeding and management. I suspect you have figured this out but it may be tougher than expected. I trust that you have tenure or at least, a good lawyer...Vaya con Dios and be not dismayed regardless! ? ?The only truly unforgivable sin...is having been right!?

 

[RideFree]

Interesting blurb in SAM

Did Researchers Cook Data from the First Test of General Relativity?

 

[Pheran]

Originally posted by: RideFree
Alex Mayer, "A testable solution to the problem of quantum gravity"


Latest from Dr. Mayer.

Also, don't dare miss the enthralling controversy at Dr Mayer's on-line site.
Good place to start is papers and make sure you follow links at the bottom.
Google is even involved! I've also had my own share of dealings with Google...

(Alex received the following via e-mail on 2 Feb. ?08)

[ Alex, ]

Considering the amount of money, the magnitude of people?s programs, status and security plus the political budgets and connections invested in the structure you are threatening to dismantle, I expect you to be ignored so long as possible and when that becomes difficult, attacked in some very unpleasant ways. Being correct about your subject will remain irrelevant, perhaps for most or even all of your lifetime unless you are either lucky or able to line up some fully committed support strong enough that it can?t be pushed around. Your best ally will probably be the internet and its bloggers. Like all rapacious beasts though, they will require careful and continuing feeding and management. I suspect you have figured this out but it may be tougher than expected. I trust that you have tenure or at least, a good lawyer...Vaya con Dios and be not dismayed regardless! ? ?The only truly unforgivable sin...is having been right!?

Nice to see I'm not the only one following Mayer's work - I really want to see his theories tested (and they are all testable!). Unfortunately his online book that had a full explanation for the Pioneer anomaly has been taken down for the time being. Where did you find this Google email?

 

[RideFree]

Originally posted by: Pheran

Where did you find this Google email?

I had downloaded it from his page but see he has taken the link down as of today or maybe earlier....

 

[RideFree]

FYI, more cosmology BS, apparently.

 

[Born2bwire]

Originally posted by: RideFree

FYI, more cosmology BS, apparently.

BS huh?

 

[RideFree]

It's all based on Edwin Hubble's Law stating that the redshift in light coming from distant galaxies is proportional to their distance.

If I understand anything from Dr. Mayer's work, it is that Ed Hubble's meat house is waiting to be torn down...along with many others. I've known that Hubble was wrong since 1977.

 

[silverpig]

Originally posted by: RideFree
It's all based on Edwin Hubble's Law stating that the redshift in light coming from distant galaxies is proportional to their distance.

If I understand anything from Dr. Mayer's work, it is that Ed Hubble's meat house is waiting to be torn down...along with many others. I've known that Hubble was wrong since 1977.

:roll:

 

[RideFree]

Originally posted by: RideFree

Originally posted by: Pheran

Where did you find this Google email?

I had downloaded it from his page but see he has taken the link down as of today or maybe earlier....

I think this link will work...it is the one i downloaded from and saved it.
at least it should work till he disconnects it.

 

[RideFree]

Originally posted by: silverpig

Originally posted by: RideFree
It's all based on Edwin Hubble's Law stating that the redshift in light coming from distant galaxies is proportional to their distance.

If I understand anything from Dr. Mayer's work, it is that Ed Hubble's meat house is waiting to be torn down...along with many others. I've known that Hubble was wrong since 1977.

:roll:

Obviously, time will tell...

 

[Born2bwire]

Originally posted by: RideFree

Originally posted by: silverpig

Originally posted by: RideFree
It's all based on Edwin Hubble's Law stating that the redshift in light coming from distant galaxies is proportional to their distance.

If I understand anything from Dr. Mayer's work, it is that Ed Hubble's meat house is waiting to be torn down...along with many others. I've known that Hubble was wrong since 1977.

:roll:

Obviously, time will tell...

30 years wasn't enough?

 

[hellokeith]

Originally posted by: RideFree
It's all based on Edwin Hubble's Law stating that the redshift in light coming from distant galaxies is proportional to their distance.

If I understand anything from Dr. Mayer's work, it is that Ed Hubble's meat house is waiting to be torn down...along with many others. I've known that Hubble was wrong since 1977.

Indeed there is some theoretical research which suggests that lightspeed has slowed down over the course of time, due to the "soup" or zero-point activity becoming more dense. This would be game-changing if ever demonstrated.

Edit: Perhaps gravity still travels at that original higher speed, while EMR is at the current value of c.

 

[RideFree]

|E| = mc²