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SharkByte
2007-May-29, 09:00 PM
I almost posted this in questions and answers because its not really a theory or anything like that but just something I was wondering about. It just seems more appropriate here because there is always the chance someone else actually believes it... lol

I was thinking about general relativity, the speed of light and all that and I got to wondering what if the laws of physics as we know them were different in different galaxies? If the laws of physics were directly effected by the nearest supermassive black hole, for example the one at the center of the milky way, how would we know? We *know* that the speed of light in a vaccum is 186,000 miles/second but if it veried as it traveled through the massive distances in the "void of space" where any number of unknown forces could be at work on it how would we recognize this and how would it effect our understanding of the universe?

zenbudda
2007-May-29, 09:57 PM
something i'd like to add to this in the form of an additional question to supplement this discussion: is there a formula that can predict how far a "certain amount of light" (ie. light from a flashlight, light from a searchlight, light from a laser) will go inside a pure vaccuum, not passing through any space dust or anything, before the itensity would disappate from the visible spectrum?

i'll try to lay it out another way. lets say i was orbiting earth about as far away as you can orbit. lets say i took a very powerful search light, and pointed it in a direction that was away from any significant source of obstruction and gravity. and let's say we had the ability to set up a detector light years away. how far away could we detect the light? i'm thinking there are many other variables here: the entensity of the light, the sensitivity of the detector etc.

nauthiz
2007-May-29, 10:05 PM
At the extreme end, if the detector is sensitive enough to detect a single photon and it were possible to filter out all other sources of light, then there would be no limit to the distance at which it would be at least theoretically possible to detect light from the source.

Peter Wilson
2007-May-30, 12:10 AM
What if the speed of light wasn't constant?

Then it would change :)

There can be no change, without something constant that the change changes with respect to; there can be no thing that is constant without things that change.

In other words, we cannot have a universe without some things that are constant, and the speed-o-light happens to be one of them :whistle:

Jerry
2007-May-30, 02:23 AM
Then it would change :)

There can be no change, without something constant that the change changes with respect to; there can be no thing that is constant without things that change.

In other words, we cannot have a universe without some things that are constant, and the speed-o-light happens to be one of them :whistle:
Perhaps.

We have very good reasons to believe the speed of light is very close to the same in every system we have studied - not only would the spectral lines be different, but fundamental chemical properties are based upon the way light - electromagnetic systems - behave.

But this does not mean that there cannot be subtle variations in the speed of light that are a function of environment, and this is one of the possibilities that is constantly being tested for. It still blows me away that we have found chemicals with a negative defractive index.

We do not know with certainty that the path of light through nearly empty space does not require an energy budget...or allow slight variations in velocity. (We do see lensing especially in the most distant galaxies - a tattle tail sign of speed variation, and this lensing is sometimes attributed to dark matter. But the existance of dark matter is not a fact, either.)

Peter Wilson
2007-May-30, 10:28 PM
Perhaps...

It still blows me away that we have found chemicals with a negative defractive index...

Is that the same as a positive refractive index?

:razz:

Chunky
2007-May-30, 10:31 PM
i was thinking..what if you can travel faster than the speed of light only when no light is present...i dont have any scientific formulas to back this claim up...but it makes sence to me...

just a thought.

Grey
2007-May-31, 05:08 PM
i was thinking..what if you can travel faster than the speed of light only when no light is present...i dont have any scientific formulas to back this claim up...but it makes sence to me...

just a thought.I can't think of any situation in which there is no light present, assuming you count any electromagnetic radiation as light. At any temperature above absolute zero, you'll have at least blackbody radiation.

John Mendenhall
2007-May-31, 05:51 PM
I can't think of any situation in which there is no light present, assuming you count any electromagnetic radiation as light. At any temperature above absolute zero, you'll have at least blackbody radiation.

Yes, the problem is not just visible light, it is the sea of photons at all wavelengths that we live in. Nereid has occasionally posted about this in ATM threads. And there are also neutrinos and (maybe) DM neutralinos. And gravity may yet prove to be electromagnetic.

Remember, the universe is not something we only observe thru telescopes. We are part of it. The universe makes galaxies, black holes, supernovas, stars. It also makes comic strips, ATM threads, hurricanes, primates, etc.

Fazor
2007-May-31, 05:58 PM
Did I miss it, or has no one pointed out that c is the speed-of-light constant in a vaccume, and is the maximum speed. From some things I read, the speed of light can be slowed, which would make it variable just never faster than c. Although the science discussed in the articles was above my knowlege, so I don't know if the speed actually is slowed, if just the energy is changed, or what the full story is. [edit: the one I can recal most from memory talked about using bose-einstein condensate to slow the speed of light passing through it. again, way past my level of education, so don't know the details].

stutefish
2007-May-31, 09:16 PM
Isn't c a constant, that expresses the relationship between mass and energy such that it is the maximum speed that anything can attain in any frame of reference (and even then only photons can actually achieve that speed, on account of only photons have the unique mass-energy relationship necessary)?

I mean, doesn't c actually have nothing at all to do with the presence or absence of light, but rather everything to do with how fast things can travel (including light, which happens to be the fastest)?

SharkByte
2007-May-31, 09:21 PM
Did I miss it, or has no one pointed out that c is the speed-of-light constant in a vaccume, and is the maximum speed. From some things I read, the speed of light can be slowed, which would make it variable just never faster than c. Although the science discussed in the articles was above my knowlege, so I don't know if the speed actually is slowed, if just the energy is changed, or what the full story is. [edit: the one I can recal most from memory talked about using bose-einstein condensate to slow the speed of light passing through it. again, way past my level of education, so don't know the details].

You are correct that C is the speed of light in a vaccume and it can be slowed by any material it passes through. I remember reading a few years ago that someone had actually succeeded in making light stop in a lab. I have no clue how they did it though.

What I was really thinking though is that if the speed of light was somehow being set by circumstances inside the milky way galaxy how would we recognize it as such? Wouldn't all of our observations be tainted by the fact that our galaxy limited light to 186Kmps? If light traveled at 517Kmps out in the void between galaxies but slowed to 186kmps when it entered the galaxy wouldn't our measurment scale be limited to 186kpms? It seems like it would be similar to putting a 1000lbs on a scale with a max reading of 500lbs. No matter how fast or heavy something really is, your always limited in your measurments by the scale with which you measure.

SharkByte
2007-May-31, 09:42 PM
Isn't c a constant, that expresses the relationship between mass and energy such that it is the maximum speed that anything can attain in any frame of reference (and even then only photons can actually achieve that speed, on account of only photons have the unique mass-energy relationship necessary)?

I mean, doesn't c actually have nothing at all to do with the presence or absence of light, but rather everything to do with how fast things can travel (including light, which happens to be the fastest)?

That actually makes sense to me.

Someone once explained this to me:

We live in a universe with 3 visible dimensions; length, width and height and the 4th dimension: time. His theory was that all objects in the universe are moving at the speed of light at all times. We are sitting on a planet which is rotating as it travels around a star which is traveling through the galaxy which is traveling through inter-galactic space which very well could be moving itself. When you add all of that up, we are moving at the speed of light. Since the speed of light is the universal constant, any change in our velocity requires an adjustment to be made somewhere else to keep the balance. Since we can't break the speed of light as we go faster the forth dimension time, slows down.

I think he was trying to explain the pardox about one twin leaving on a space ship and traveling for a year at .75c while the other twin stayed stationary on earth. I can't remember how exactly he tied it in but it was an interesting way to look at it anyways... lol

Thanatos
2007-Jun-01, 06:01 AM
A non constant speed of light would change everything. It would also be useless. I think it is a bad approach.

Mr. Peabody
2007-Jun-02, 10:46 PM
Speed of light changes based only on the density of the media it traverses.
Does the "space" between galaxies always have the same density? If a Higgs field exists between galaxies (and throughout all space) a variation in it's density would alter the measurement of c in that context. As the local galaxies, including the Milky Way approach, we move closer to the center of gravity of the local group. The density of the Higgs field will be greater, and the measure of c thru "space' will decrease. This will be very slight and hard to measure. See "the speed of light may have changed through time" to see observed evidence of this.

Michael Noonan
2007-Jun-02, 11:26 PM
The speed of light is based in distance per unit time. So if you vary distance or time then the speed of light is variable but travels at the speed of light relative to the media it is travelling in.

Here on earth in the gravitation of our galaxy and solar system it is 186,000 miles per second. Space and time is curved from Einstein's work so any variation of that causes light to act as if travelling in a medium.

Take a look at the dark matter density map found by the Hubble telescope link (http://imgsrc.hubblesite.org/hu/db/2007/01/images/a/formats/web_print.jpg).

To me it looks like a river flow look with lots of little eddies and vortecies. Light would travel through these at the speed of light relative to the density of the medium. To what effect this density has on the matter in the vortecies, now that is interesting, cheers.

It would still be travelling at light speed just at

north
2007-Jun-03, 04:22 AM
The speed of light is based in distance per unit time. So if you vary distance or time then the speed of light is variable but travels at the speed of light relative to the media it is travelling in.

Here on earth in the gravitation of our galaxy and solar system it is 186,000 miles per second. Space and time is curved from Einstein's work so any variation of that causes light to act as if travelling in a medium.

Take a look at the dark matter density map found by the Hubble telescope link (http://imgsrc.hubblesite.org/hu/db/2007/01/images/a/formats/web_print.jpg).

To me it looks like a river flow look with lots of little eddies and vortecies. Light would travel through these at the speed of light relative to the density of the medium. To what effect this density has on the matter in the vortecies, now that is interesting, cheers.

It would still be travelling at light speed just at

think refraction though.

as in light through water bends , BECAUSE the speed of light SLOWS down.

Sticks
2007-Jun-03, 05:58 AM
I read somewhere that measurements of the speed of light had shown that over a long period of time it was decreasing.

jamini
2007-Jun-03, 01:51 PM
think refraction though.

as in light through water bends , BECAUSE the speed of light SLOWS down.

What's your point? Water is hardly a vacuum.

jamini
2007-Jun-03, 03:34 PM
The speed of light is based in distance per unit time. So if you vary distance or time then the speed of light is variable but travels at the speed of light relative to the media it is traveling in. [sic][emphasis added]
This is what Newton thought he accomplished with his famous bucket experiment. However Einstein demonstrated that an ether was not only unnecessary for light propagation but also superfluous as an absolute reference frame. Indeed, there are no absolute frames of reference in SR; just as there are no preferred accelerated reference frames in GR. The speed of light is relative only to the observers' frames of reference.

Am I misunderstanding your statement or are you prepared to argue an ATM theory in favor of an ether and contrary to GR?

ZaphodBeeblebrox
2007-Jun-03, 06:49 PM
That actually makes sense to me.

Someone once explained this to me:

We live in a universe with 3 visible dimensions; length, width and height and the 4th dimension: time. His theory was that all objects in the universe are moving at the speed of light at all times. We are sitting on a planet which is rotating as it travels around a star which is traveling through the galaxy which is traveling through inter-galactic space which very well could be moving itself. When you add all of that up, we are moving at the speed of light. Since the speed of light is the universal constant, any change in our velocity requires an adjustment to be made somewhere else to keep the balance. Since we can't break the speed of light as we go faster the forth dimension time, slows down.

I think he was trying to explain the pardox about one twin leaving on a space ship and traveling for a year at .75c while the other twin stayed stationary on earth. I can't remember how exactly he tied it in but it was an interesting way to look at it anyways... lol

Not Exactly ...

What it ALL Boils Down to, Is The Speed of Liight is The Pythagorean Sum of your Speed through Space and your Speed through Tiime, As Suuch it Becomes a Geometric Expression!

The Way it Works, Is All of The Four Dimensions Exist at Mutual Riight-Angles, Hard to Visualize in Four but Three is Easier and Two Wiill Suffice, Picture your Speed of Travel through Space, as The Short Leg of a Very Long Riight Triangle, Said Leg is your Speed of Passage through Tiime, And The Speed of Liight itself Is Represented By The Triangle's Hypotenuse, So Long as The Length of The Short Leg is a Tiiny Fraction of The Length of The Long Leg, The Speed of Liight and The Speed of Tiime are Relatiively Identical; However, as The Length of The Short Leg Increases, i.e. you Speed Up, The Length of The Long Leg Decreases to Compensate, i.e. Tiime Slows Down, As The Hypotenuse Remains The Same Length, i.e. Speed of Liight is Constant, wiith The Special Case of Liight in a Vacuum, Whose Speed through Tiime Equals Zero, Ergo, Tiime Appears to Stop ...

Thus, The Defiined Speed of Liight, Not to Be Confused wiith The Actual Speed of Any Giiven Photon, Can No More Change wiith Respect to The Universe as a Whole, as The Length of The Hypotenuse of a Riight Triangle Can Change wiith Respect to its Other Two Siides; Furthermore, Any Attempt to Intimate that it Has Ever Done So, Is Mere Creationist Propaganda (http://www.talkorigins.org/faqs/c-decay.html)!

Grey
2007-Jun-03, 07:14 PM
I read somewhere that measurements of the speed of light had shown that over a long period of time it was decreasing.I've only seen that claim by creationists, who are hoping that a decreasing speed of light could explain how we can see galaxies millions of light years away in a universe only 6,000 years old. And they generally try to support that claim by carefully picking which data they include. Have a look at the discussion here (http://www.bautforum.com/showthread.php?p=947303#post947303).

Mr. Peabody
2007-Jun-04, 08:12 AM
The accurate way to measure change in c is to use the same method of measuring it over a period of months/years.

If these accurate measurements show fluctuation, then the Higgs field is less homogenous than I expected, fluctating up and down in the short time frames, moving eventually higher or lower in the long range (like the stock market).

We are a very long way from the local galaxies, and a long way from the center of gravity we should all be approaching....

Nereid
2007-Jun-04, 01:43 PM
Why is this thread in the ATM section?

jamini
2007-Jun-04, 04:41 PM
Why is this thread in the ATM section?

If for no other reason, I would suggest that this opinion is ATM although it would appear to be off topic:

The accurate way to measure change in c is to use the same method of measuring it over a period of months/years.

If these accurate measurements show fluctuation, then the Higgs field is less homogenous than I expected, fluctating up and down in the short time frames, moving eventually higher or lower in the long range (like the stock market).

We are a very long way from the local galaxies, and a long way from the center of gravity we should all be approaching....

The hypothetical Higgs particle has not yet been detected and there is certainly no evidence to demonstrate any universal “center of gravity that we should all be approaching.”

Mr. Peabody: Is this an ATM theory of yours that you are prepared to defend?

.

Harry Palmer
2007-Jun-04, 07:24 PM
Setterfield's and others observational evidence for a falling c is weak.

But WI a definite drop had been observed over the last 150 years, say from 300,500 kms to 299,500 kms: what would be the (ignoring Creationist claims) implications for cosmology and physics (a falling c is said to be not incompatible with Relativity)?

ZaphodBeeblebrox
2007-Jun-04, 09:48 PM
Setterfield's and others observational evidence for a falling c is weak.

But WI a definite drop had been observed over the last 150 years, say from 300,500 kms to 299,500 kms: what would be the (ignoring Creationist claims) implications for cosmology and physics (a falling c is said to be not incompatible with Relativity)?
UGH, Not Setterfield Again ...

As Noted in The Previously Posted Liink (http://www.talkorigins.org/faqs/c-decay.html), to Call his Scholarshiip Disingenuous, Is to Insult Used-Car Salesmen Everywhere ...

As I Pointed Out Above, The Speed of Liight Being a Constant is THE Foundation of Modern Cosmological Thought; If it Were Proven to Not Be Constant, The Entirety of Known Physics, Would Become as Useful as Alchemy, an Interesting Footnote in The Hiistory of Scientific Thought, But Nothiing Moore!

Grey
2007-Jun-05, 01:10 PM
As I Pointed Out Above, The Speed of Liight Being a Constant is THE Foundation of Modern Cosmological Thought; If it Were Proven to Not Be Constant, The Entirety of Known Physics, Would Become as Useful as Alchemy, an Interesting Footnote in The Hiistory of Scientific Thought, But Nothiing Moore!I disagree. Really, the value of the speed of light tells us something about the nature of spacetime. If it were changing over time, that would tell us that something about space is likewise changing. But current physics could probably be modified to allow for it. It would certainly have some interesting implications, but would not make us throw out everything we've put together. The foundation of physics and astronomy is not a single postulate; it's the experimental data that agree well with our theory.

John Mendenhall
2007-Jun-05, 05:40 PM
Isn't c a constant, that expresses the relationship between mass and energy such that it is the maximum speed that anything can attain in any frame of reference (and even then only photons can actually achieve that speed, on account of only photons have the unique mass-energy relationship necessary)?

I mean, doesn't c actually have nothing at all to do with the presence or absence of light, but rather everything to do with how fast things can travel (including light, which happens to be the fastest)?

Oh, would that everyone did their homework like stutefish.

Fix these ideas firmly in your head: the speed of light in a vacuum is measured as the same by any observer, and the laws of physics are the same throughout the universe. If this is not true (my apologies, long term members, but I haven't beat on this point for 6 weeks), then GPS and airplane radios and airborne radar don't work. Neither do particle accelerators and gravitational lensing. The current theories describe the universe to a phenomenal degree of accuracy (see Wiki article). If you want go against the mainstream, you have to account for everything that the mainstream has been able to describe since Tycho Brahe et al.

Jerry
2007-Jun-06, 10:33 PM
We know that when we measure the speed of light near the sun, it appears to be slower. What we do not know with certainty is if the space is curved as Einstein theorized, or if the light is actually moving through space near the sun more slowly. If Einstein is correct, we should be able to detect gravity waves about...........now.

Extrapolating, we do not know with certainty that the speed of light in an absolute vacuum near the earth moves at the same speed that light would move in a vacuum at a greater distance from a massive body. This is one of the possible explanations for the Pioneer anomalllly.

ZaphodBeeblebrox
2007-Jun-07, 02:19 AM
We know that when we measure the speed of light near the sun, it appears to be slower. What we do not know with certainty is if the space is curved as Einstein theorized, or if the light is actually moving through space near the sun more slowly. If Einstein is correct, we should be able to detect gravity waves about...........now.

Extrapolating, we do not know with certainty that the speed of light in an absolute vacuum near the earth moves at the same speed that light would move in a vacuum at a greater distance from a massive body. This is one of the possible explanations for the Pioneer anomalllly.
Jerry, thiis is your Own, ATM Theory ...

Would Be The Better Place to Discuss that, No?

Mr. Peabody
2007-Jun-07, 04:29 AM
the laws of physics are the same throughout the universe. If this is not true (my apologies, long term members, but I haven't beat on this point for 6 weeks), then GPS and airplane radios and airborne radar don't work

BB theory depends on the laws of physics changing throughout time and space.

The fluctuation in c would only be enough to sway GPS measurable in units smaller than microns. You do the math...

Typically, every generation of mankind believes science has all the answers. I don't believe so now, or ages ago.

Most cosmologists believe in dark matter, but can't say what it is.

Most BB theorists believe in in dark matter in an attempt to salvage bad galaxy theory,i,e, the fact that galaxies spin at the same rate from inner to outer rim (observation), unlike any observed vortex of collapsing matter that they believe it is.

Bad galaxy theory is spawned by bad big bang theory, dismissed by Steven Hawking, Einstein, Newton, and every country that has the metric system ( all of them but US). Can you say crisis in cosmology conference three times fast?

The BB theorists used three methods to prove the universe 13.7 billion years old, correct?

Hubble took pictures 15 billion years into the distance(15 billions years in the past) to observe a field of galaxies that look like galaxies in our time/area.There were even elliptical galaxies, which take many billions of years to form.

The picture of a universe 12 billion years ago should be exponentially hotter, more dense, and moving very rapidly (which observation disproves).

"Hubble deep field":

http://antwrp.gsfc.nasa.gov/apod/ap980607.html
http://antwrp.gsfc.nasa.gov/apod/ap981012.html

Unfortunately when I called NASA on this, they disconnected the link that places the age at 15 billion years.
Ask yourself, if we have Hubble, which can look much further back in time than 15 billion years, why is Nasa and BB theorists afraid to use it?

According to NASA and BB theorists- "These Galaxies should not exist":

http://antwrp.gsfc.nasa.gov/apod/ap980607.html

30 problems w/BB
http://www.metaresearch.org/cosmology/BB-top-30.asp

If dark matter exists, why can it only form itself (?!) between arms of galaxies, which would only temporarily result in motion that we observe (in violation of conservation, and laws of thermodynamics and motion)? Why can't it be Higg's which is accepted by the science community and who's existence has been proven neccessary?

To progress, we need to use observations, the scientific method, and logic, and sometimes go beyond our "best guess" answers which are molded around unproven theories (like BB theory).

STATUS QUO SITS FOR A SERVING OF SLICED SCIENCE

In a plush back room the status quo met
Compared the size of their government checks
They then settled down in self-righteous excitement
Were served fine wine to add to the delight
Now comes the time for the purposeful meeting
To each in turn give new insights a beating
With mindless arguements and political ploys
Each voice gives fallacy to the deafening noise
To mire in stagnation will pacify the group
As progress diverts funding and spoils the mood
Many more drinks were poured that hour
In celebration of smugness purchased by power
Using position as barrier or lever
Assuring that science could never advance ever

Jerry
2007-Jun-17, 11:26 PM
Jerry, thiis is your Own, ATM Theory ...

Would Be The Better Place to Discuss that, No?
The fundamental question posed on this thread, is whether or not the speed of light is variable. There have been a number of posts stating that it is an absolute constant, without any qualifications. We know the speed of light through a medium is slower than it is in a vacuum. We also know great masses can 'bend space', which is analogous to 'slowing the speed of light' near very dense objects. But 'bending space' is only a valid explanation if gravity waves passing thorugh space also exist, and to date, we have zero evidence supporting this hypothesis. This has little to do with the fact that opposing theories of light exist: General Relativity should not be treated like an absolute truth.

Mr. Peabody
2007-Jun-19, 06:55 AM
We also know great masses can 'bend space', which is analogous to 'slowing the speed of light' near very dense objects. But 'bending space' is only a valid explanation if gravity waves passing thorugh space also exist, and to date, we have zero evidence supporting this hypothesis.

The "bending of space" is not "known" or proven.

The only accurate way to predict the position of heavenly bodies is to assume the force of gravity is perpetuated instantly. A "wave" would have to take some time to traverse from body to body.

The more advanced the method of measuring the speed of gravity, the closer we get to instant perpetuation, the most advanced measurment shows a speed no less than many, many times the speed of light.(See Meta Research).

Dense objects, per my theory, attract more Higgs, creating a more dense Higgs field, a more dense media resulting in light traversing slower.

The bending of space and the dilation of time are creating variables out of constants, tantamount to the laws of physics fluxuating. These variations would make light travel at different speeds ( as c is a function of space travelled divided by time). This is not observed or necessary for proven theory.

If time were not a constant, objects moving slower in time would not exist as of yet in our time.....

Space is defined as a given area, it is not a physical object which has properties, it cannot bend or change size.

Jerry
2007-Jun-19, 02:33 PM
...like the gravity wave, the Higgs boson has been a no show. Otherwise, I agree with your definition of space, and I like your explanation for why time is a necessary constant in real space! Let me embellish: ...otherwise objects moving slower in time would cease to exist.

Grey
2007-Jun-19, 03:01 PM
The only accurate way to predict the position of heavenly bodies is to assume the force of gravity is perpetuated instantly. A "wave" would have to take some time to traverse from body to body.

The more advanced the method of measuring the speed of gravity, the closer we get to instant perpetuation, the most advanced measurment shows a speed no less than many, many times the speed of light.(See Meta Research).No, actually, Van Flandern is mistaken here. Relativity correctly predicts the motion of objects with a gravitational influence that travels at the speed of light, and no more. What he fails to realize is that the gravitational effect is based not just on the position of the object, but also on its velocity and acceleration. That's similar to electromagnetic effects, which also propagate at the speed of light, but in that case, only the velocity is involved.

Also Jerry, it's not true to say that we have "zero evidence" of gravitational radiation. It is true that they have not been observed directly. However, there is some pretty good indirect evidence. For example, general relativity predicts a certain loss of energy due to gravitational radiation from systems such as binary pulsars. When compared (http://arxiv.org/PS_cache/astro-ph/pdf/0407/0407149v1.pdf) with the observations, the agreement is excellent.

Jerry
2007-Jun-19, 08:23 PM
Also Jerry, it's not true to say that we have "zero evidence" of gravitational radiation. It is true that they have not been observed directly. However, there is some pretty good indirect evidence. For example, general relativity predicts a certain loss of energy due to gravitational radiation from systems such as binary pulsars. When compared (http://arxiv.org/PS_cache/astro-ph/pdf/0407/0407149v1.pdf) with the observations, the agreement is excellent.

Even with 30 years of observations, only a small portion of the north-south extent of the emission beam has been observed. As a consequence, our model is neither unique nor particularly robust. The north-south symmetry of the model is assumed, not observed, since the line of sight has fallen on the same side of the beam axis throughout these observations. Nevertheless, accumulating data continue to support the principal features noted above.

Impressive, however, it is this same set of parametric assumptions which convinced scientists that when LIGO reached the current level of sensitivity, there would be a high probability of the detection of gravity waves. (This probability has been revised downward to about 50%/yr. In part, due to earlier LIGO and other GW null observation constraints.)

If the energy is being transmitted away as gravity waves as W&T have calculated, we should detect the waves with LIGO antenna/telescopes. It is quite ironic that the 'proof of gravity waves' provided by W&T become a locally verifiable constraint upon the same transmissions.

baric
2007-Jun-19, 09:06 PM
I never understand questions like these... The speed of light is a defined constant. Asking what would happen if it varied would be like asking "what if the length of a meter varied" or "what if the mass of electrons was different"

People need to also realize that the original source of the "speed of light is variable" questions were from Young Earth Creationists who were intent on explaining why galaxies appear to be millions of years old (based on light distance) when they KNEW that the universe was only 6000 years old.

Thanatos
2007-Jun-24, 08:47 AM
Jerry, you are contradicting yourself, IMO.

astrocat
2007-Jun-24, 04:56 PM
I almost posted this in questions and answers because its not really a theory or anything like that but just something I was wondering about. It just seems more appropriate here because there is always the chance someone else actually believes it... lol

I was thinking about general relativity, the speed of light and all that and I got to wondering what if the laws of physics as we know them were different in different galaxies? If the laws of physics were directly effected by the nearest supermassive black hole, for example the one at the center of the milky way, how would we know? We *know* that the speed of light in a vaccum is 186,000 miles/second but if it veried as it traveled through the massive distances in the "void of space" where any number of unknown forces could be at work on it how would we recognize this and how would it effect our understanding of the universe? What an excellent field to choose. Speed, even the Speed of Light, is a factor of Time (and Distance) and Time, according to GR (General Relativity) slows down near a Black Hole. When a Black Hole eats another Black Hole, it takes forever for them to get togetherr, they just kind of 'melt' into each other's embrace - that's extrapolating on this particular tennet of GR.

Philip Janes
2007-Jun-25, 02:34 AM
I think it is well established that physical processes governed by electromagnetic forces, such as emission spectra of ionic transitions in atoms, obey general relativity within the bounds of conditions that can be tested. That is consistent with our belief that electromagnetic forces propagate at the speed of light. Since our definitive time standards are slaved to those processes, we have, in effect defined the speed of light to be constant.

It remains to be seen whether the nuclear forces also propagate at light speed. If not, then we might detect changes in the half-lives of radio isotopes relative to atomic clocks. Such variations, if they exist could be dependent on time, motion, gravity fields or electromagnetic fields. Decay of subatomic particles conceivably might also vary independently of the speed of light.

The question that started this thread might have been more properly stated as, "What if we defined the relationship between time and distance according to some standard other than the speed of light?" The beauty of special relativity is the symmetrical relationship between time dialation and length shortening. If the speed of light were permitted to vary in deference to some other standard of constancy, I believe a different kind of relativity would emerge; it could be equally valid, but probably not as elegant in its symmetry. :cry:

John Mendenhall
2007-Jun-28, 01:51 PM
No, actually, Van Flandern is mistaken here.

Agreed, Van Flandern is really mistaken. See the Wiki article on the speed of gravity. Newtonian mechanics does assume that the speed of gravity is instantaneous. Newton recognized that this could not be correct, but could not find the reason that it worked; so he used it. Yet another tribute to Newton's genius, and to Einstein's genius 300 years later when general relativity showed that the direction of the perceived force lies along the line to the current position of the gravitating object, while limiting the propagation velocity of gravity to the speed of light.

Research before you post. Guys like us will make mincemeat of you if you don't, and eat doughnuts at the same time. Check out the toroid thread, also.