Violations of Relativity

[admiral_ju00]

Since it seems that this month(well, September anyway) is dedicated to Einstein by at least several of the Pop Sci magazines, I've just picked up a copy of SciAm and Discover as they talk about him quite extensively.

 

One thing I came to pretty quick was a mention of Violation(s) to Relativity, and something that I'd like to get more examples.

 

What can be considered a Violation of either the Special Theory of Relativity as well as the possible violations to the General Theory of Relativity?

 

I'm looking for examples really, like traveling faster than C, etc, but any further elaboration is welcome.

[fermions]

oh.. is there any violations of relativity? I'm not sure about that... even exceeding the speed of light means nothing if no information is transferred...

anyway I've heard we're able to stop a light for some time...

[Thales]

Any out an out violations of relativity, that exist in the real world would have been headline news, so the answer would be, other than hypotheticals, that there aren't any that we know of.

 

Thats the beauty of Einstein's theories, written nearly 100 years ago and yet to be disproved...

[K. B. Robertson]

Any out an out violations of relativity' date=' that exist in the real world would have been headline news, so the answer would be, other than hypotheticals, that there aren't any that we know of.

 

Thats the beauty of Einstein's theories, written nearly 100 years ago and yet to be disproved...[/quote']

 

 

Dear Thales Baryon...

(Here's hoping Upper doesn't condemn this as 'off topic'?):

 

Thank you beyond measure for inadvertently or deliberately 'stealing' one of my favorite - cross-cut, over & under, ripcurling - saws... Somehow, I think you authored that observation in distilled, independent innocence and inspiration. May the Buddha smile upon you and yours. (Sir <Or Madam?>)

- Equus

 

And now, this:

 

 

 

From: "David Sicks"

To: kraziequus@yahoo.com,

Subject: RE: Science Forums Post

Date: Tue, 24 Aug 2004 02:35:19 -0600

 

 

Unhuh, Gulliver in Lilliput, and so on....

 

Nevermind, have a look at this:

 

http://zebu.uoregon.edu/~imamura/123/lecture-5/olbers.html

Olbers's Paradox

 

(for a similar picture for galaxies)

 

 

There is a simple, seemingly trivial question one can ask -- Why is the night sky dark?

 

 

This question was originally posed many years ago by a series of people (Kepler, Halley ===> Jean de Cheseaux ===> Heinrich Olbers [1823]). The answer to this seemingly simple question is not trivial and tells us profound things about the Universe.

 

 

Assumptions:

 the Universe is finite in size

 the stars fill the Universe uniformly

 each star has a luminosity L

 the inverse square law holds, i.e., the flux of energy from a star (energy flow per second per unit area) is given by f = L / (4 pi D2 ). Here L is the intrinsic luminosity of the star and D is its distance from us.

 

 

Consider a shell of stars of thickness T and radius R.

 

How much light do we receive from this shell of stars?

 Well, the flux of energy from one star is f = L / ( 4 pi R2 )

 By inspection of the figure, if there are n stars per unit volume of the shell, then the total number of stars per shell is N = n x volume = n x 4 pi R2 x T

 The total amount of flux we receive from the shell is then F = f x N = L x n x T ===> a pretty simple and interesting result.

 

The key point is that the amount of light we receive from the shell does not depend upon how far away the shell is. We receive the same amount of light from distant shells as we do from nearby shells.

 

Hmmmmmm.

 

So, if there are million such shells in the Universe, then we simply multiply the contribution of 1 shell by million to get the total amount of energy we receive from the Universe. Further, we should see this light at all times, even at night, since the shells completely surround us. This type of reasoning gave rise to Olbers's Paradox

 

Another View:

 

Another way to think about the problem is to compare the brightness of the night sky to the brightness of the surface of the Sun. Just as obviously, we know that the surface of the Sun blazes away at a temperature of 5,800 Kelvin. The night sky is substantially less bright. To see why this is a paradox consider the following:

 

 A star (like the Sun) of radius R covers an area of size, A = pi R2. This is straightforward. The fraction of the surface area of a sphere of radius r covered by such a star is then fraction = f = pi R2 / (4 pi r2 ) = [R/2r]2.

 The total fraction of the shell covered by all of the stars in the shell ===> fraction due to one star x total number of stars = [R/2r]2 x [ n x 4 pi r2 x T ] ===> fraction of the shell covered is ~ 5 x 10-16 x n x T

 

Here, I measured the stellar density n as the number of stars per cubic parsec and the thickness of the shell in parsecs. Recall that 1 parsec = 3.26 light years. These are convenient units because in our Galaxy, there is roughly 1 star per cubic parsec and the average separation between stars is on the order of 1 parsec.

 

The fraction of the shell blocked out by the stars in the shell does not depend upon the radius of the shell (how far away the shell lives) ===> Olbers's Paradox if the Universe is big enough.

Resolution of Olbers's Paradox

 

Okay, so what's the way out? Something must be wrong with one (or more) of the original assumptions, or some physics has not been considered. Possibilities:

 

 obscuration by dust ===> distant stars are blocked out and appear fainter. Turns out this won't work because dust, if it absorbs energy will heat up and re-radiate the energy. This means that the Universe will still be filled with the same amount of radiation, the dust acts simply as a go-between so to speak.

 

 Expansion of the Universe 1 ===> redshift of photons ===> W(observed) is larger than W(emitted) ===> we absorb lower energy photons than are produced by the distant stars.

 

Expansion of the Universe 2 ===> Imagine that the star (galaxy) produces 1 photon every second. If there is no relative motion between the star and us, then we will also see photons (energy) fly by at the same rate (===>same luminosity). However, if the star is moving away from us then we will see the photons fly by a slower rate than 1 per second. This means that the energy will arrive at the Earth at a slower rate ===> a lower luminosity.

 

The preceding effects conspire to make distant objects in an expanding universe have apparent brightnesses which fall off faster than the inverse square law. This decreases the contributions from distant shells. The expanding universe effects partially explain Olbers's Paradox.

 

 One shell of stars covers a fraction = 5 x 10-16 x n x T of the sky. So, to make the night sky as bright as a star, we would like to make the stars cover most of the observable sky. This means that 5 x 10-16 x n x T x number of shells ~ 1.

 

To calculate the number of shells, we note that there is roughly 1 star per cubic parsec in our galaxy ===> average distance between stars in our Galaxy (shell thickness, T) is ~ 1 parsec (explain why).

 

===> number of shells ~ 1 / [ 5 x 10-16 ] ~ 2 x 1015

 

Because each shell is ~ 1 parsec thick ===> Universe needs to be at least 2 x 1015 parsecs in radius. Recall that 1 parsec = 3.3 light years and so the Universe must be at least 6.6 x 1015 light years in size in order to make the night sky as bright as the surface of the Sun.

 

 The current Universe is only 8 - 12 billion years old and so has an observable size of only 8 - 12 billion light years. This is much less than needed to produce Olbers's Paradox.

 The fact that the Universe has a finite age is the principal explanation of Olbers's Paradox.

 

My note: Is this a faulty fact/assumption? (See below.)

 

It is interesting that in asking and answering the seemingly trivial question, "Why is the night sky dark?" one could have inferred that the Universe was expanding and that the Universe had a finite age (or at the least the stars and galaxies had finite ages).

 

My note: Distant primordial quasars (their light originates near the far distant boundaries of the seemingly 13.7 billion year old universe) observed by the Hubble Space Telescope have been found to be receding from Earth at .93 C. Stars closer to us appear to be receding at a lesser fraction of the speed of light.

 

If a shell of stars exists at a somewhat greater distance such that its stars are receding from Earth at exactly 1.0 C, then those stars and any more distant stars cannot be seen. Their recession relative to Earth is so fast that their light can never reach us. This supposed 1.0 C recession shell marks the "event horizon" of the theoretically observable universe (so far as Earth folk are concerned). If this recession event horizon exists, (again, I believe the most distant celestial objects observed to date are receding at speeds a bit less than 1.0 C) than the Universe could be much "older" than 13.7 billion years. In so, we could never know the true "age" of the Universe; it could be infinitely old and infinitely extensive.

 

This would appear to be consonant with Kent Benjamin Robertson's (also, to some extent, Thomas Gold's) Steady State view of the Universe; it has no beginning and no end, either in time or space. It's just constantly, proportionally expanding.

 

Thus, Newton rises to impact the apple.

 

Thus, dabbling in these various theories and technical observations, I'm struck by the fact that human sensibilities are fit to human scales and dimensions, ie, not to microscopic scales or astronomic scales / dimensions. We can observe and think about these extrasensory things, but we're mostly fooled insofar as we think of nature only in the realm of human nature.

 

 

 

 

http://zebu.uoregon.edu/~imamura/123/lecture-5/lecture-5.htmlhttp://zebu.uoregon.edu/~imamura/123/lecture-5/lecture-5.html

 

...............................................................................................

[Martin]

Since it seems that this month(well' date=' September anyway) is dedicated to Einstein by at least several of the Pop Sci magazines, I've just picked up a copy of SciAm and Discover as they talk about him quite extensively.

 

One thing I came to pretty quick was a mention of Violation(s) to Relativity, and something that I'd like to get more examples.

 

...[/quote']

 

with calm deliberation, you have let down the floodgates of silliness

 

actually it is sort of interesting as a topic of conversation. I havent seen the September Sigh Ham. do they mention superluminal recession speeds?

 

If they gave a list of (apparent) violations of SR, they would probably mention that GR predicts that distant-enough galaxies have to be receding faster than c.

 

there is something else that is potentially more interesting than superluminal recession (which is pretty much a fact of life, fitting with the observations and based on Hubble law)

 

they may or may not have mentioned this---it comes up in Quantum Gravity Phenomenology and there was a conference about it this year in February.

 

remember that Galilean relativity was almost but not quite right and it had to be bent or tweaked just slightly in 1905---to get SR----in a way that only showed up in very special circumstances such as something traveling very fast.

 

suppose that SR itself is not quite right and that IT needs further tweaking to make it fit nature better. but suppose the discrepancy is unmeasurably small EXCEPT where a photon has very high energy and has traveled a long ways like for a billion years.

 

Picture two photons emitted at the same instant in a Gammaray burst (where some individual photons can have really awesome energies like TeV.) Suppose one is much more energetic than the other and that they travel for a billion years.

 

Suppose that after a billion years the more energetic photon has pulled out ahead, just enough to detect.

 

An instrument called GLAST, scheduled for orbit in 2007 or so, is designed so it can detect this kind of thing.

 

It is something people will be looking for.

 

there is no theoretical reason 1905 SR should be absolutely correct. It might be only approximately correct for the kind of much lower energy light we can make in laboratories and for the very short time periods we can watch it. There might, in theory, be a very slight (planck scale) effect where higher energy photons go a tiny bit faster

 

and c is just the low energy limit----something which the great mass of everyday photons obey to the accuracy we can measure.

 

It doesnt pay to believe in Dogmas. So some of your tax dollars go to people who are able to imagine that the speed c might be a prevalent low energy limit and that GLAST might observe that the law needs a bit of tweaking to fit nature better. So maybe SciAm pointed this out?

 

Anyway they had this Quant Grav Phenomenology conference where they talked about a number of these projects (GLAST is not the only one) planned and ongoing. It was Feb 4-14 in Poland and the lectures are mostly available on line

 

http://ws2004.ift.uni.wroc.pl/html.html

(just click on "lectures" to see what can be downloaded)

 

nice topic Admiral, wish Id seen the SciAm, may have to look at it just to see what violations they listed