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Wiley
2002-Jan-09, 11:47 PM
Besides GPS, does anyone have any examples of practical applications of relativity?

Chip
2002-Jan-10, 12:17 AM
On 2002-01-09 18:47, Wiley wrote:
Besides GPS, does anyone have any examples of practical applications of relativity?


I don't know how "practical" this is, but probably the next direct "application" for general relativity could be within the Laser Interferometer Gravitational Wave Observatory (http://www.ligo-wa.caltech.edu/).

DStahl
2002-Jan-10, 01:29 AM
I don't really expect this will pass muster as "practical," but I once read a patent for a method of "reducing the mass of objects relativistically for ease of transport." I think I saved the patent number; I'll just have a look-see...be right back...
-------------
OK, here's the actual abstract:

"This invention is a method for producing transient fluctuations in the inertial masses of material objects employing an effect that is a consequence of relativistic theories of gravitation. An extension of this method wherein pulsed thrust is applied sychronously with the mass fluctuations produced by the method to an object makes it possible to cause stationary changes in the object's apparent mass and weight and also to facilitate the transport of massive objects."

Hey, what do I know? Check the patent yourself: US Patent 5280864 (http://164.195.100.11/netacgi/nph-Parser?TERM1=5280864+&Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2Fsrchnum.htm&r=0&f=S&l=50)

--Don

<font size=-1>[ This Message was edited by: DStahl on 2002-01-09 20:35 ]</font>

GrapesOfWrath
2002-Jan-10, 02:05 AM
On 2002-01-09 18:47, Wiley wrote:
Besides GPS, does anyone have any examples of practical applications of relativity?

Are you aware of the Dirac equation, important in quantum mechanics? That equation incorporated special relativity.

Chip
2002-Jan-10, 06:22 AM
On 2002-01-09 20:29, DStahl wrote:
I don't really expect this will pass muster as "practical," but I once read a patent for a method of "reducing the mass of objects relativistically for ease of transport." I think I saved the patent number; I'll just have a look-see...be right back...
-------------
OK, here's the actual abstract:

"This invention is a method for producing transient fluctuations in the inertial masses of material objects employing an effect that is a consequence of relativistic theories of gravitation. An extension of this method wherein pulsed thrust is applied sychronously with the mass fluctuations produced by the method to an object makes it possible to cause stationary changes in the object's apparent mass and weight and also to facilitate the transport of massive objects."

Hey, what do I know? Check the patent yourself: US Patent 5280864 (http://164.195.100.11/netacgi/nph-Parser?TERM1=5280864+&Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2Fsrchnum.htm&r=0&f=S&l=50)
--Don


---------------------------------------------
Hi DStahl ,

Could this be the first unintended, tentative step toward the transporter as depicted on Star Trek?

P.S. The engineer in me also sees the old fashioned arc welder (rather than a gun) as the first tentative step toward the Star Trek phaser. Just imagine an arc welder with tremendous energy, and the "rods" melting out the front rapidly in a focused beam. Well...on second thought, I don't think the world needs that right now. /phpBB/images/smiles/icon_frown.gif

Chip

John Kierein
2002-Jan-10, 12:31 PM
E=Mc^2. Atomic energy. Nuclear power plants. etc.

Wiley
2002-Jan-10, 11:09 PM
On 2002-01-09 21:05, GrapesOfWrath wrote:
Are you aware of the Dirac equation, important in quantum mechanics? That equation incorporated special relativity.


Doh! Of course. I should've thought of that.

I was looking for applications that effect most people's daily life. Quantum field theory is at the heart of the semiconductor industry, and this fits the bill quite nicely.

Thanks y'all!

odysseus0101
2002-Jan-11, 03:12 AM
Hi DStahl ,

Could this be the first unintended, tentative step toward the transporter as depicted on Star Trek?

P.S. The engineer in me also sees the old fashioned arc welder (rather than a gun) as the first tentative step toward the Star Trek phaser. Just imagine an arc welder with tremendous energy, and the "rods" melting out the front rapidly in a focused beam. Well...on second thought, I don't think the world needs that right now. /phpBB/images/smiles/icon_frown.gif

Chip



Chip,

It has always seemed to me that a transporter would work best if it only transmitted data, rather than an actual substance. This device would make a complete map of every atom in the object, and that data would be transmitted to the other end, at which point another device would reconstruct the object atom by atom. So rather than physically move me (this body), the data on this body would be sent, and when the new one was constructed this one would be destroyed. Sure, it opens all sorts of cans of worms, caterpillars, and other assorted squiggly things, but I think it's more efficient than actually transporting objects.

DStahl
2002-Jan-11, 06:02 AM
Chip--

I don't think this is a Star Trek transporter sort of thing, though I'm not Trekkie enough to know for sure. It seems more like some sort of platform you put a caterpillar tractor on which then makes the tractor weigh only 10 lbs so it can be carried around easily. As the chatroom kids say, ROFL!

--Don

Chip
2002-Jan-11, 06:08 AM
On 2002-01-10 22:12, odysseus0101 wrote:
Chip,

It has always seemed to me that a transporter would work best if it only transmitted data, rather than an actual substance. This device would make a complete map of every atom in the object, and that data would be transmitted to the other end, at which point another device would reconstruct the object atom by atom. So rather than physically move me (this body), the data on this body would be sent, and when the new one was constructed this one would be destroyed. Sure, it opens all sorts of cans of worms, caterpillars, and other assorted squiggly things, but I think it's more efficient than actually transporting objects.


=====

Yes, there was an article in Scientific American early last year about what you described. (The "no clone" method of teleportation.) Also, if an object (or person) could be more or less painlessly "scanned" rather than destroyed, you'd have the cloned teleportation method. At the receiving platform you'd have all the raw materials on hand to recreate the teleported traveler. (The worms and caterpillars you mentioned also involve such sticky items as personality, memory, etc..) What happens to all that?

What intrigued me in this thread was the implication of lowering mass for conventional transport. What if there was a way to greatly reduce mass? (Not size or shape - just mass.) Within a shell of negative energy, one perhaps could have no mass relative to the outside universe. The speed of light might be possible without violating nature's laws.

I think another type of virtual teleportation could involve projection. The subject never really leaves, but is partially projected through space to a reassembly chamber, there they are reprocessed holographically or recreated out of available raw material. They (or their computer memory) stays on Earth and conducts exploration (or diplomacy) on Alpha Centauri over a four-year time lag via a transmited beam! (Might replace TV in the future!) /phpBB/images/smiles/icon_wink.gif

Chip

Chip
2002-Jan-12, 08:10 PM
On 2002-01-11 01:02, DStahl wrote:
Chip--

I don't think this is a Star Trek transporter sort of thing, though I'm not Trekkie enough to know for sure. It seems more like some sort of platform you put a caterpillar tractor on which then makes the tractor weigh only 10 lbs so it can be carried around easily. As the chatroom kids say, ROFL!

--Don


OK - yes. (See second paragraph in my previous sloppily written post to odysseus0101.) I was thinking that if mass were lowered (how I don't know,) a material object could perhaps be better prepared for transport, or transmission, (or teleportation?)

Anyway - I'm drifting away from the subject at hand. Interesting stuff though! /phpBB/images/smiles/icon_biggrin.gif

Chuck
2002-Jan-13, 12:20 AM
Put the tractor in a huge, rigid, sealed box with enough helium to make it register as one ounce when placed on a scale. Then put a 34 cent stamp on it and mail it.

Well, it's more likely to work than the patented method.

<font size=-1>[ This Message was edited by: Chuck on 2002-01-12 19:21 ]</font>

Donnie B.
2002-Jan-13, 12:36 AM
Wouldn't work. The box would exceed the maximum dimensions for parcel post...

/phpBB/images/smiles/icon_biggrin.gif

Now, maybe if you could fold that box into a few of those 10 curled-up extra dimensions, you could get it under the limit...

David Simmons
2002-Jan-13, 05:51 AM
On 2002-01-09 18:47, Wiley wrote:
Besides GPS, does anyone have any examples of practical applications of relativity?


I believe that the design of large color-television picture tubes requires that account be taken of relativistic mass increase in order to make the electron beam land on the right color spot on the tube face.

Chip
2002-Jan-14, 06:17 AM
On 2002-01-09 18:47, Wiley wrote:
Besides GPS, does anyone have any examples of practical applications of relativity?



On 2002-01-13 00:51, David Simmons wrote:

I believe that the design of large color-television picture tubes requires that account be taken of relativistic mass increase in order to make the electron beam land on the right color spot on the tube face.

============================================
Hey that's interesting. Do you know of a source for this information? Magazine article or (probably very technical) book? (I like to collect examples of relativity too.)
Chip



<font size=-1>[ This Message was edited by: Chip on 2002-01-14 01:21 ]</font>

Bob
2002-Jan-14, 04:20 PM
I believe that the design of large color-television picture tubes requires that account be taken of relativistic mass increase in order to make the electron beam land on the right color spot on the tube face.
[/quote]

I'm skeptical about that statement. The non-relativistic equation for the velocity of a charged particle accelerated from rest through an electrical potential Vis:
v = sqrt(2 * q* V / m)

For an electron this is 592,674 * sqrt V

For 1000 volts, v is 6 % of the speed of light with a mass increase of a small fraction of 1 percent. Sounds negligible to me.

Karl
2002-Jan-14, 06:07 PM
I'm skeptical about that statement. The non-relativistic equation for the velocity of a charged particle accelerated from rest through an electrical potential Vis:
v = sqrt(2 * q* V / m)

For an electron this is 592,674 * sqrt V

For 1000 volts, v is 6 % of the speed of light with a mass increase of a small fraction of 1 percent. Sounds negligible to me.


TV CRT voltage is more typically 25-30kV for ~30% light speed.

Silas
2002-Jan-15, 11:25 PM
Alas, the light-speed "speed limit" is a terribly *impractical* thing, and that aspect of relativity is a doggone nuisance!

(Then again, perhaps our closest interstellar neighbors are content with us at a distance... You know, watching all our old tv shows... What must they think of us?)

(The speed-of-light limit is apparently becoming an obstacle in microprocessor design...)

re the Star Trek transporter, gasp! Has none of you read "Spock Must Die" by James Blish? (The first "Star Trek Novel.") Matter isn't destroyed and re-created; it is persuaded to make a "Dirac Jump" to its new location. (Great book, with absolutely the highest quality Trek-Science-Babble: Blish knew enough *real* science to make it worthwhile.)

Silas

David Simmons
2002-Jan-16, 04:45 AM
On 2002-01-14 01:17, Chip wrote:


On 2002-01-09 18:47, Wiley wrote:
Besides GPS, does anyone have any examples of practical applications of relativity?



On 2002-01-13 00:51, David Simmons wrote:

I believe that the design of large color-television picture tubes requires that account be taken of relativistic mass increase in order to make the electron beam land on the right color spot on the tube face.

============================================
Hey that's interesting. Do you know of a source for this information? Magazine article or (probably very technical) book? (I like to collect examples of relativity too.)
Chip



I can't find any articles on the design of such cathode ray tubes. Further reading on the subject convinces me that the relativistic mass change would be used only in sizing of bias magnetic fields on the color guns.

The amount of deflection in a magnetic deflection system depends, among other things like the velocity of the electron, on the ratio sqrt(e/m); e is electron charge and m its mass (inertia).

When a TV is adjusted, one such adjustment is "color convergence" which is making sure that each color gun hits the correct place on the color mask in the CRT. This is done by positioning or changing the magnetic field of fixed electromagnets associated with the gun, and each set has to be individually adjusted. That electromagnetic field would have to be sized so that it accounted for the change in inertia of the electrons as a result of their high velocity. So the account taken of relativity in the design would be in the coarse sizing of the adjustment magnets and not any "fine tuning."

At least that's what I get out of my reading.

odysseus0101
2002-Jan-16, 06:17 AM
(The speed-of-light limit is apparently becoming an obstacle in microprocessor design...)


I'm sorry to get things a bit more off the subject of astronomy, but I'm going to anyway. The above-quoted statement has reminded me of a few things that hopefully some of you can shed some light on (with apologies for the heliocentric metaphor).

I recall reading that some scientists had slow light down to only a few mph using the Bose-Einstein condensate (of course I have no idea what that is), and I also remember reading a German(?) researcher (maybe using a similar method) recently claimed to make light travel faster than light because the end of the signal came out of a chamber before the beginning. If anyone could point me in some directions on this I would be most appreciative. I would try to look this stuff up on my own, but because this is nowhere near my area of expertise I have no way of evaluating the quality/accuracy of the writing.

On a related note, I heard something recently about quantum mechanics being useful in a new generation of computers. Using individual atoms as transistors and taking advantage of quantum mechanics, such that each atom can be both binary values simultaneously, this computer would be extraordinarily small and fast.

DStahl
2002-Jan-16, 06:37 AM
The last or last-but-one issue of Science News mentioned that some guys have built a very tiny LED that pops out one and only one photon at at time. That may be very useful in quantum computing.

As far as super-fast light goes, I think it's a quantum effect that isn't very useful for something like computing because it takes advantage of the uncertainty in a photon's position and cannot (for reasons I can't give you) be used to transmit any information. Grr, that's not a very good response. I'll post back after I've rummaged about for a better answer.

--Don (the other, newer one)

<font size=-1>[ This Message was edited by: DStahl on 2002-01-16 01:38 ]</font>

Donnie B.
2002-Jan-16, 09:03 PM
On 2002-01-16 01:17, odysseus0101 wrote:

I recall reading that some scientists had slow light down to only a few mph using the Bose-Einstein condensate (of course I have no idea what that is), and I also remember reading a German(?) researcher (maybe using a similar method) recently claimed to make light travel faster than light because the end of the signal came out of a chamber before the beginning. If anyone could point me in some directions on this I would be most appreciative. I would try to look this stuff up on my own, but because this is nowhere near my area of expertise I have no way of evaluating the quality/accuracy of the writing.

On a related note, I heard something recently about quantum mechanics being useful in a new generation of computers. Using individual atoms as transistors and taking advantage of quantum mechanics, such that each atom can be both binary values simultaneously, this computer would be extraordinarily small and fast.


[being lazy and not reorganizing the quotes]

In the case of the B-E condensate, it's probably not light, but the atoms that need to be slowed way down. A B-E condensate is a small (so far) ball of atoms that are so cold and close together that they act (quantum-mechanically) as a single entity. This means all the atoms have to move very, very slowly, both kinetically and vibrationally. I believe B-E condensates have been formed of groups of up to a few hundred atoms, and have been kept in that state for fairly long periods (minutes?)

The "faster-than-light-light" is still controversial. It involves passing pulses of light through crystals with specific properties. The crystal tends to "spread out" the light pulse, and the leading edge of the pulse seems to come out "too soon"... that is, seems to get through the crystal faster than light travels in a vacuum. It has not yet been demonstrated that this technique can really carry information superluminally.

Quantum computing is indeed a hot topic of research. There is some indication that it could be used to solve problems that take a lot of processing time with traditional computers, such as pattern recognition, code breaking, and certain kinds of minimization problems. However, they are still in the very earliest stages of development, and it's not certain if they'll be useful for general-purpose computing.

Wiley
2002-Jan-16, 10:26 PM
On 2002-01-15 18:25, Silas wrote:
Alas, the light-speed "speed limit" is a terribly *impractical* thing, and that aspect of relativity is a doggone nuisance!

(The speed-of-light limit is apparently becoming an obstacle in microprocessor design...)



Yep, the speed of light is becoming an obstacle in microprocessor design. But we use field theory (i.e. classical EM) to model these circuits; hence, relativity is not used. Unlike astronomy, I get paid to do this modeling. /phpBB/images/smiles/icon_smile.gif

I need more examples!

DStahl
2002-Jan-17, 06:43 AM
Wiley: "Yep, the speed of light is becoming an obstacle in microprocessor design. But we use field theory (i.e. classical EM) to model these circuits; hence, relativity is not used."

Interesting line of work. As I understand it you guys aren't bumping up against relativity so much as hitting the point where classical EM yeilds to quantum electrodynamics, right?

Wiley: "Unlike astronomy, I get paid to do this modeling."

Wow, an engineer, and a model too! /phpBB/images/smiles/icon_wink.gif

--Don [the west-coast one]

Karl
2002-Jan-17, 05:02 PM
On 2002-01-09 18:47, Wiley wrote:
Besides GPS, does anyone have any examples of practical applications of relativity?


Here is some text regarding a class of microwave vacuum tubes.

http://crppwww.epfl.ch/crpp_theo.htm

The quasi-optical gyrotron is a device in which an annular relativistic electron beam creates high-frequency (>100 GHz) and high-power (>100KW) electromagnetic radiation used for plasma heating at the electron cyclotron frequency (ECRF). The efforts of the theory group are focussed on the development of numerical codes for the design (DAPHNE) and the physics (G2DP) of the gyrotron. The DAPHNE code is used for the gun designs in collaboration with other laboratories as well as industrial partners (ABB, Thomson-TTE). The physics codes G2DP permit to simulate both the electrostatic and the electromagnetic instabilities which can develop in gyrotron beams.

And free-electron lasers:

http://sbfel3.ucsb.edu/www/vl_fel.html

A Free Electron Laser generates tunable, coherent, high power radiation, currently spanning wavelengths from millimeter to visible and potentially ultraviolet to x-ray. It can have the optical properties characteristic of conventional lasers such as high spatial coherence and a near diffraction limited radiation beam. It differs from conventional lasers in using a relativistic electron beam as its lasing medium, as opposed to bound atomic or molecular states, hence the term free-electron.

http://books.nap.edu/books/NI000099/html/16.html#pagetop

(Added FEL info)

<font size=-1>[ This Message was edited by: Karl on 2002-01-17 12:34 ]</font>

Added NAP link to FEL



<font size=-1>[ This Message was edited by: Karl on 2002-01-17 14:19 ]</font>

EckJerome
2002-Jan-18, 05:28 PM
On 2002-01-09 18:47, Wiley wrote:
Besides GPS, does anyone have any examples of practical applications of relativity?


Okay, color me confused...how is GPS (global positioning system, I presume) a "practical application of relativity?"

Eric


<font size=-1>[ This Message was edited by: EckJerome on 2002-01-18 12:29 ]</font>

Donnie B.
2002-Jan-18, 05:56 PM
Because of the high accuracy required in GPS computations, relativistic corrections are applied. Or so I'm told; I've never seen the details.

ToSeek
2002-Jan-18, 06:41 PM
On 2002-01-18 12:56, Donnie B. wrote:
Because of the high accuracy required in GPS computations, relativistic corrections are applied. Or so I'm told; I've never seen the details.



Some of the details (http://www.phys.lsu.edu/mog/mog9/node9.html)

Wiley
2002-Jan-18, 07:17 PM
On 2002-01-17 01:43, DStahl wrote:
Wiley: "Yep, the speed of light is becoming an obstacle in microprocessor design. But we use field theory (i.e. classical EM) to model these circuits; hence, relativity is not used."

Interesting line of work. As I understand it you guys aren't bumping up against relativity so much as hitting the point where classical EM yeilds to quantum electrodynamics, right?


There are essentially two types of modeling:
1.) Interconnect modeling - does the signal get from point A to point B intact?
2.) Device modeling - What do you do with signal at point B?

Device modeling is almost entirely based in quantum theory. And the smaller the device, the nastier the theory. Interconnect modeling is all classical EM (or circuit theory approximations to EM) and this is the slowdown. When you halve the size of a device, you halve the response time. When you halve the size of the interconnect, you also double the resistance and consequently no you get no gain in speed.

Wiley
2002-Jan-18, 07:28 PM
On 2002-01-18 12:56, Donnie B. wrote:
Because of the high accuracy required in GPS computations, relativistic corrections are applied. Or so I'm told; I've never seen the details.


In addition to the website ToSeek mentioned, try Taylor & Wheeler, "Exploring Black Holes: Introduction to General Relativity". It's very low level, so if you have had college physics (with calculus), you'll easily be to understand it. If I offended anyone who has taken more math and physics courses than Taylor and Wheeler combined by underestimating their mathematical prowess, feel free to go directly to Wald's book.

Gsquare
2002-Jan-21, 11:38 PM
... does anyone have any examples of practical applications of relativity?


Good question.
How about a cesium clock whose resonant frequency of oscillation varies with altitude (due to diffences in gravitational potential) and with relative velocity? Thus the clock rate is altered by differences in g and by relative velocity changes.
There are others:

The doppler shift in spectral lines of receeding objects with low velocity is usually linear:
z = [lambda - lambda(0)] = v/c

But with large values of z the special relativistic relation must be used; as with large z quasars and the like.
-------------------------------------------
Likewise, gravitational redshift can be thought of as due to general relativistic effects.

Other possibilities depend upon what you may consider as a practical relativistic effect:
The existence of a magnetic field can be shown to be simply a special relativistic effect of motion through an electric field.

G^2


<font size=-1>[ This Message was edited by: Gsquare on 2002-01-21 21:35 ]</font>

Gsquare
2002-Jan-22, 02:54 AM
"This invention is a method for producing transient fluctuations in the inertial masses of material objects employing an effect that is a consequence of relativistic theories of gravitation.


Thanks Don for this patent.
Woodward is somewhat famous in this regard; I believe he actually constructed the device and took measurements ...Correct?

It seems to be based on sound theory; I think problems arise due to the transient (rather, oscillatory) nature of the phenomena, making it difficult to obtain accurate data.
It is quite interesting and seems to point, again, in my opinion, to the fundamental nature of inertia mass as arising from the vacuum (as per Puthoff & Haisch, et al).

G^2

NottyImp
2002-Jan-23, 12:19 PM
Since there's a lot of talk on this thread about Trek, here's a link to a book that looks at all the "developments" in Trek from a physicist's perpspective, including the transporter, and in some detail. I enjoyed it...

http://www.amazon.com/exec/obidos/ASIN/0465005594/qid=1011793675/sr=1-2/ref=sr_1_10_2/002-5872690-5568835

DStahl
2002-Jan-24, 12:01 AM
G^2: "Woodward is somewhat famous in this regard; I believe he actually constructed the device and took measurements ...Correct?"

I haven't researched the fellow one bit. I ran across his patent when I was trolling patent databases for oddities. I don't know for a fact that he uses GR correctly, nor do I know that anyone has confirmed his experimental results. I have noticed that there are a fair number of unconventional researchers who report things that other scientists cannot duplicate. I'll see what I can find out about Woodward.

Don Stahl

[Later] Well, the gentleman is no John Newman, but there has been difficulty reproducing his results (see these notes from David Cyganski (http://www.inetarena.com/~noetic/pls/Papers/cyganski.html)) and apparently Woodward has uncovered an instrument problem which may have amplified his positive results by a factor of 10 to 100. A technical analysis and report on preliminary attempts at reproduction of Woodward's results by David Cramer is from Nasa (http://www.lerc.nasa.gov/WWW/bpp/pdf/Cramer-JPC.pdf) in PDF format.

None of this means Woodward's work is mistaken, merely that it's a more or less controversial result.

Don, Again

<font size=-1>[ This Message was edited by: DStahl on 2002-01-23 20:14 ]</font>

Gsquare
2002-Jan-24, 05:11 AM
Thanks again Don for the links; Very interesting. I'll read up on it when I get some time.
G^2