Slashdot Mirror
Testing Relativity
MGDruss writes "NASA are proposing an empirical measurement on the ISS which would test general relativity to a precision within the bounds of superstring (and other) theories to predict deviation." We mentioned the Cassini experiment last year.
Which theory do you think will win? Seriouslly, this is really exciting. As an avid Physics buff I am really looking forward to the outcome.
What ever happened to the concept that the simplest explaination is probably the best?
Can I bum a sig?
Now all of the Trekkies will realize that Warp 10 isn't possible.
Relativity has already been put to the test. I mean, if time wasn't flexible, how else would Arthur Dent be able to witness the end of the universe every evening at Milliways?
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
This is probably going to be marked flamebait or offtopic but this experiment could have been unmanned. If anyone claims this is a good reason to have a manned space station, I defy them to specify how having humans aboard is needed in this case.
Now geology, that's a different story.
Blaze a trail to the New World
The article implies that Einstein's relativity is incorrect, in the opinions of most scientists. I'm no physicist, but I would say that most scientists are trying to build onto Einstein's relativity and show that it agrees with Quantum Mechanics: Therefore, they think it is correct.
Simon's Rock College
http://jamesphogan.com/bb/archives/relativity.shtm l#081797
SUGGESTED NASA EXPERIMENT Posted on August 17, 1997 contents
RELATIVITY EXPERIMENT
A couple of weeks ago, a friend of mine at NASA invited me to submit any suggestions I might have for possible experiments to be carried out by future mission, involving advance physics. Since a few people have been in touch regarding the skepticism I've expressed in the past about the basis of Relativity, I thought my response might be of general interest, and so reproduce it below.
[To give credit where due, a virtually identical proposal was submitted to NASA some years ago by the late engineer and metallurgical consultant, Carl Zapffe. Nothing came of it. If anyone thinks I'm way off the mark, I'd be happy to hear from them.]
Dear Les,
Herewith the following, offered in response to your invitation.
INTERFEROMETRY BEYOND THE TERRESTRIAL MAGNETOPAUSE
The Einstein Special Relativity Theory (SRT), we all "know," forms one of the cornerstones of modern physics. Its predictions are utilized on a routine basis, and it has withstood every experimental test.
These predictions boil down, essentially, to applications of the principles of (i) mass-energy equivalence (E=mc*2), (ii) mass dependence on velocity, and (iii) time dilation. Experiments verifying these relationships have been performed with increasing precision in the course of the past century. These are the proofs that the textbooks cite in support of SRT, and which its defenders point to when questions are raised concerning Relativity basics.
But it turns out that _all_ of them can be derived by purely classical procedures, independently of any Relativistic considerations. They don't say anything unique about SRT at all. (i) follows from the principle of conservation of momentum and Maxwell's equations. Carl Zapffe gives three derivations in his book "A Reminder on E+mc*2," with numerous references that show how it was implicit in the physics known at the end of the nineteenth century. Regarding (ii), Petr Beckmann, in his "Einstein Plus Two" (1987), shows how the increase of "mass" with velocity arises as a manifestation of the electrical inertia of charges moving through fields--analogous to aerodynamic drag.
Essentially, these are effects arising from the energy differences of relatively moving systems. The question they lead to is whether the results observed regarding (iii) (e.g. the extended lives of cosmic-ray muons) are in fact confirmation of "time" being dilated, as per SRT, or result from the physical slowing-down of clocklike processes in motion through a field. The only way to test this empirically would be to sit on an incoming muon and observe whether the laboratory clocks (at rest in the field) also slow down (as the observer-referred SRT holds) or speed up (as a field-referred theory would predict). This has never been done. (A whole literature exists on all this, but I don't think that here would be the place to elaborate further.)
So, the standard proofs turn out not to be proofs at all. All that's left, then, is the interpretation of the 1881 Michelson-Morley attempt to measure an "ether wind," and its many variations performed since.
The null results returned by these experiments have two possible interpretations: (1) There is no ether; (2) the ether local to the Earth is entrained in its orbit around the Sun. (1), of course, is the orthodox line. The constancy of the speed of light for all observers is a _postulate_ that follows from accepting this interpretation. Contrary to common belief, it has never been verified experimentally. (The claimed verifications all involve round-trip measurements that average out the c+/-v velocities that arise in field-referred theories.) Having thus conferred constancy on a velocity, it then becomes necessary to distort space and time in order to preserve it. This, in effect, is what the transformation equations of SRT do.
Treating th
That is often true but... what is that simplest solution? People compare string/M-Theory to how the geocentric view of the universe was justified. People had supposed a heliocentric view of the world, but people believed that there were epicycles and such instead of that.
Where is the simpler solution here? General Relativity and Quantum Mechanics are NOT compatible in many cases (for example extremely small but extremely heavy objects like black holes cause things like infinite probabilities which does NOT make sense). We have no simpler solution. String theory is about all we have now.
The "Evicting Einstein" title of the article is misleading. IMHO, the Theory of Relativity cannot be proven incorrect...it can only be proven *incomplete*. Far too much evidence/data exists to prove the interaction of light and gravity and space-time as predicted by the GTR.
Even if the Quantum theory is proven correct, the Theory of Relativity will live on as an effect of the quantum theory - since it explains the effects of Quantum behavior on the macro-level...something that Quantum physics is not very good at. Just like the General Theory of Relativity proved that Newtonian physics was not incorrect, just incomplete, the Quantum theory will prove to be a superset of the GTR.
An Indian-American Hindu committed to non-violent thought/speech/action alarmed by the global explosion of radical Islam
Is it no surprise then that the EU wants to cancel the ISS? Even with the faults the station has, it's still the best way to conduct low gravity experiments. It's intolerable that the Europeans want it over and done with.
If you read the article, you will see this is not a "low gravity experiment". They are placing an interferometer aboard the ISS, above atmospheric distortion. An unmanned rocket would probably do the job more cheaply. But, as long as governemnts are already wasting billions of dollars sending people up to the ISS, we might as well give the interferometer to them and tell them to turn it on, thus sparing a separate rocket launch.
This still doesn't mean the ISS is anything other than a giant orbiting multibillion dollar turkey.
The dude who invented this principle phrased it this way (translated from the Latin): "Entities should not be multiplied more than necessary." But what entities are "necessary"? To Ockham, God was a necessary entity, yet you hear Ockham's Razor used to deny the existence of God.
Bottom line: OR is a highly subjective tool that should be applied with great care. And even then, it can mislead you -- the simplest plausible theory can still be wrong, due to evidence you haven't seen. OR is a strategy for coming up with good theories, not a law of nature!
You're probably referring to Occam's Razor. One way of expressing that principle is that if two theories completely and correctly explain a phenomenon, the simpler one is preferred. If you think the simplest explanation is always correct, you're liable to believe that me when I say "apples fall towards the Earth because that's where you plant them" or "the Earth was created 5000 years ago". There's more to truth than simplicity.
Gates' Law: Every 18 months, the speed of software halves.
M-Theory & Supersymmetry attempt to unify the efforts of those scientists studying string theory by making a self-consistent, simple, and elegant explanation for the why of everything. It attempts to resolve the basic, fundamental issues that quantum theory and general/special relativity have failed to answer. If this experiment happens, we may be able to determine whether we need to look for another contender, or whether the strange world of M-Theory is the path to follow. Hurrah!
Check The Official String Theory site if you're confused about all these concepts. When you've done that, you will have gained some answers, but will of course get even more questions. :-)
Beware: In C++, your friends can see your privates!
Loop quantum gravity predicts that space comes in discrete lumps, the smallest of which is about a cubic Plank length, or 10^-99 cubic centimeter. Time proceeds in discrete ticks of about a Plank time, or 10^-43 second. The effects of this discrete structure (non-continuous) might be seen in experiments in the near future. One of these will be measuring radiation from distant gamma-ray bursts. These occur billions of light-years away and emit a huge amount of gamma rays within a short span. According to loop quantum gravity, each photon occupies a region of lines at each instant as it moves through the spin network that is space. The discrete nature of space causes higher-energy gamma rays to travel slightly faster than lower-energy ones. The difference is tiny, but its effect steadily accumulates during the rays' billion-year voyage. If a burst's gamma rays arrive at Earth at slightly different times according to their energy, that would be evidence for loop quantum gravity. The GLAST satellite, which is scheduled to be launched in 2006, will have the required sensitivity for the experiment. Recommend the cover story of this past January's Scientific American. Also an online pdf giving more technical details is available at http://arxiv.org/ftp/physics/papers/0108/0108026.p df
I cannot easily envisage a picorad - but an accuracy of 1cm in 300 million km !!! I'm more use to working with plus or minus half a brick, it's close enough for government work.
Semper ubi sub ubi
1000 years from now, they prove that the theory of relativity is true and then travel back in time and tell Einstein who explains the principals to us and through the act of putting it in textbooks makes us 'take their word for it' since noone can understand it.
To me, this is a very simple explanation and since the simplest explanation must be true, I think we have a winner.
I call it the 'Spears theory of enlightened time-travelers'.
Slight sidebar perhaps...
In the article it says that GPS would not be possible without the use of Relativity Theory.
Why is this? Is it due to time dilation effects at the speed of the satellites?
Or something else I'm not thinking of?
String theory predicts deviations from General Relativity at very high energies and very small distances. I would be very surprised to read of a string theory model -- or class of models -- that predicted solar system scale effects in their basic framework. The importance of string theory effects is suppressed by a huge factor depending on the local energy density in the experiment you are testing. The string energy scale is so far away that it would be a great coincidence if it just barely showed up in the solar system but did not, e.g. rip it all apart. Sort of like crashing your car through the window of a bookstore and having the resultant mess just precisely turn one page of one book.
This is not a bad experiment to do, because there are theories -- mostly cosmological ones -- that predict differences in gravity that would show up in this theory, but they are definitely non-standard modifications to particular theories. I have done work on these kinds of theories, and let me tell you, it is a certain amount of work to actually generate theories that even care about such low energies and large distances that you can test them even with an "ultimate" measurement.
I am disappointed by the rather slipshod understanding of science and the issues that this article represents. "Evicting Einstein" is a sensationalistic headline, and it's just not true -- as anyone will tell you, Newton was not "impeached." A much better angle that this article could have taken was that of exploration of gravity, as opposed to "putting the chalk scribblers in place."
Protect your liberties. Donate to the ACLU
if you are testing GR in the framework of GR, then you are not learning anything new.
I am the Alpha and the Omega-3
Oh wait, I've confused Science with religion, again.
This issue is a bit more complicated than you think.
as IIS and wondered why, if they're doing something as advanced as this, they don't have the intelligence to use apache?
Karma: Negative (Mostly affected by dorm trolling)
TOS: the warp scale was in multiples of the speed of light. Warp 1 speed of light, warp 2 twice the speed of light.(Enterprise should follow this scale though I haven't paid that close of attention.)
NG: Warp scale got rewritten. warp 8 is roughly warp 14 on the old scale. warp 5 is warp 8 on the old scale. So when the NCC-1701-D hit warp 8 in episode 1, they traveled the same speed that ncc-1701 hit in the TOS.
Warp 10 in NG is equal to being all places in the universe at the same instance.
Now what kind of geeks are you.
i thought once I was found, but it was only a dream.
James P. Hogan believes that special relativity is wrong. I don't care what he believes about it. But my enjoyment of fiction is severely hampered when he begins having fictional characters take the soapbox and deliver lectures that I disagree with.
On his claims that SR has not been verified, I've followed detailed discussion of the issue before on sci.physics, and the sad reality is that SR has been tested to incredible accuracy. In fact it has been tested to such accuracy that deviations to it have been detected. For a commercial example, GPS did not work correctly until they added a general relativistic correction term to the clocks to account for the fact that, being farther from the Earth, they suffered less of a dilation from the Earth's gravity field.
I have yet to see any proponent of throwing out special relativity manage to explain that level of accuracy, or come up with a decent alternative to general relativity for GPS systems.
Heh. The reason (1) is the "orthodox line" is because (2) is ruled out by stellar aberration. Michelson-Morley says that if the ether exists, it must be dragged along with the earth. Stellar aberration says that if the ether exists, it must be stationary.
I imagine that this is the cause of NASA's perplexing refusal to take up Mr. Hogan's proposal.
Actually, there are science-based satellites launched on a regular basis. I attended a meeting of a NASA hydrology working group this weekend in which we discussed a bunch of satellite mssions including GRACE, Hydros, Aquarius, ICEsat, CryoSat, and others that have either gone up in the last ~2 years or are going up soon. And those are just missions with relevance to hydrology. In more general terrestrial remote sensing, both Aqua and Terra are big platforms that have gone up in the last few years. So in actuality, there are quite a lot of satellite missions being launched all the time. Something like this, with an important purpose relevant to a lot of scientists, probably stands a pretty good chance. I don't actually know how much it would cost, but I would bet on the order of a few hundred million dollars, if its similar in cost to the other platforms mentioned.
Jokes get ruined when you splain them. But I won't let that stop me. Woman says the world is supported by a turtle. Physicist says "what's holding up the turtle?" Woman says another turtle. Physicist asks "and what's holding up that turtle?" And she says "I see. You're very clever. But you can't fool me, it's turtles all the way down!"
or something like that.
First of all, I suggest you do go to the trouble to read the article. It is interesting and, amazingly enough, it answers your question. We know that GR doesn't work for really tiny things. We know that it works for really big things. We want to know more about how it works in the in-between area. Therefore we are doing this experiment.
You are implying that theories are either right or wrong and if they are wrong they are not right at all. For starters, this is wrong. Just because you know something is not totally right, doesn't help you know what way to go to fix it. Think of it like this: your computer is broken. Any of the following could be the cause:
1. The CRT in your monitor stopped working.
2. Your hard drive won't spin up.
3. The RAM fell out.
4. The BIOS doesn't work.
5. The CPU died on you.
6. You have a non-system disk inserted.
7. There's a blackout.
We are in effect testing the pieces one at a time here rather than going to the store and buying a new black-box computer.
Scott
So, how do the astronauts on ISS feel about attempts to measure their deviation? And what type of scientists have come up with deviation theories?
I'm waiting for the creation of mini-holes at the new Large Hadron Super Collider over in Europe around 2006-7. If that type of energy could be harnessed, who needs "Mr. Fusion", gasoline, H2, or any other energy substance? Just take unbiodegradible trash and run a city on 1 ton of it.
;-) (and a 1100 lbs heavier black hole)
-- As a note, one gram of pure U235, if converted to pure energy (100% efficency, e=MCC) would power New York city for 1 day. A black hole with top spin is theorised that you could extract 45% of it's mass as inertial energy. 1 ton of crap means you have 900 Lbs of "energy".
Past that, if he was a fraud... he was a damned clever one at that.
--
Greg Egan's latest novel, Schild's Ladder is highly recommended for anyone interested in seeing what might go wrong if you test the fermament of reality a little too much. Seismic-shocks-in-the-aether is a pretty impressive feat for the author! A lot more is packed into the 327 pages than is taken in at first reading, and, frankly, it is not for anyone who didn't enjoy True Names by Vernor Vinge. Though the testing of physical theories to their theoretical limits is the very basis of Schild's Ladder, for a proper build up to this novel, his other novels and short story collections are an excellent preparation - probably best read in order, except with Teranesia set aside for the 'come down period' after everything else has been read (perhaps a few times). Schild's ladder is very much a synthesis of all the journey's Egan's stories have taken, and an exploration of the ultimate perils and pitfalls of unit testing the universe!
p.s. if you only read one Greg Egan, try Axiomatic; reading all 18 short stories in one sitting is like eating an entire box of chocolates at once -- your mind feels sickly sweet and luciously overloaded with Egan's amazing ideas. Here's the list of titles to whet the appetite:
Oliver's Law: Experience is something you don't get until just after you need it.
Actually, Occam's Razor is not "the simpler theory is usually the right one," it is "create no unnecessary hypotheses." That may sound the same, but it's not. For example, many religions posit a soul or other non-corporeal entity that persists after the death of the body. Modern science doesn't claim to have a firm grip on sentience and awareness, but it appears to be a highly complex system of nervous reactions. (I imagine most of the Slashdot crowd knows that a complex system of conditionals, like a computer, can seem very life-like.) The point is, the mechanistic understanding of awareness explains it without recourse to a soul. Consider the natural chemicals in our bodies that contribute to mood, or artificial chemicals (like drugs or alcohol) that can alter one's personality, or even cases of trauma to the head, and "soul" is left as nothing but a non-explanation -- an unnecessary hypothesis.
p ri nciples.asp
Another non-explanation is the idea that "warped space" explains gravity. All it does is push the explanation back one step from "what is gravity?" to "why do masses warp space?" So which is the correct theory? I don't think there is one, and our ideas or "understanding" of the universe will continue to evolve with everything else around us. The Pythagoreans believed that math was truth, and that reality was merely an imperfect shadow of the real world hidden beyond the veil of our senses. Well, this isn't the Matrix, an no amount of passion for "perfect" answers (like "elegant" equations or crystal spheres in the sky) will make it so.
You want an alternative theory? Give Tom Van Flandern's Meta Model a try. It may be no better than the orthodoxy of Einsteinian Relativity and quantum mechanics, but at least it won't resort to mathematical trickery and the comforting reassurance of what we'd LIKE to believe. A good introductory article may be found at:
http://metaresearch.org/cosmology/physicshasits
The only way to test this empirically would be to sit on an incoming muon and observe whether the laboratory clocks (at rest in the field) also slow down (as the observer-referred SRT holds) or speed up (as a field-referred theory would predict). This has never been done. (A whole literature exists on all this, but I don't think that here would be the place to elaborate further.)
This has been done, many times. Parent post is a crackpot.
Coming from the guy who off the top of his head knew that "In the last episode of STTNG there is reference to Warp 13 (in the future Enterprise). This future time was only about 25-30 years from the TNG "present" which means it was in the same time period as the Voyager episodes"