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Stellar Trio Could Put Einstein's Theory of Gravity To the Test

samzenpus posted about 9 months ago | from the there's-a-first-time-for-everything dept.

Space 106

sciencehabit writes "In a cosmic coup, astronomers have found a celestial beacon known as a pulsar in orbit with not one, but two other stars. The first-of-its-kind trio could soon be used to put Einstein's theory of gravity, or general relativity, to an unprecedented test. 'It's a wonderful laboratory that nature has given us,' says Paulo Freire, a radio astronomer at the Max Planck Institute for Radio Astronomy in Bonn, Germany, who was not involved in the work. 'It's almost made to order.'"

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Happy Sunday from The Golden Girls! (-1)

Anonymous Coward | about 9 months ago | (#45875667)

Thank you for being a friend
Traveled down the road and back again
Your heart is true, you're a pal and a cosmonaut.

And if you threw a party
Invited everyone you knew
You would see the biggest gift would be from me
And the card attached would say, thank you for being a friend.

Re:Happy Sunday from The Golden Girls! (0)

Anonymous Coward | about 9 months ago | (#45875851)

Preach!

Re:Happy Sunday from The Golden Girls! (5, Funny)

Anonymous Coward | about 9 months ago | (#45876039)

Your heart is true, you're a pal and a cosmonaut.

God dammit I keep seeing this posted here over and over with the same error every time. Every time!

It's "you're a GAL" you dipshits!

Re:Happy Sunday from The Golden Girls! (1)

LordLimecat (1103839) | about 9 months ago | (#45876665)

What the heck do exchange address lists have to do with anything?

Re:Happy Sunday from The Golden Girls! (0)

Anonymous Coward | about 9 months ago | (#45881687)

I thought he was referring to the Spanish counterterrorism corps.

If only /. beta was tested as much as Einstein is. (0, Offtopic)

Anonymous Coward | about 9 months ago | (#45875723)

I'm very happy to see that Einstein's theories are being tested. I only hope that the Slashdot beta site underwent even a minimal level of testing before it was unleashed upon us. But given its many, many flaws, I have doubts that any testing was performed. Come on, Slashdot. The new design is atrocious. There is so much wasted space. The stories are harder to read. The story pictures are too damn large. The discussions are difficult to read and participate in. The site feels like it loads a lot slower for me.

Please, get rid of the beta. I would be very disappointed it if ever went live, especially if the existing site (which itself is a big step backward from its predecessors) becomes unavailable at that time. The beta site is clearly a failure. The comments I've seen about it indicate near-universal hatred for it. Since it's so unwanted and so despised by everyone, it'd be best just to scrap the entire project.

Re:If only /. beta was tested as much as Einstein (4, Insightful)

Virtucon (127420) | about 9 months ago | (#45875775)

Isn't that the point of a Beta release? To obtain feedback and to fix what isn't right with something?

Re:If only /. beta was tested as much as Einstein (3, Insightful)

DMUTPeregrine (612791) | about 9 months ago | (#45876015)

Some problems shouldn't make it past the design phase, let alone through alpha and into beta.

Re:If only /. beta was tested as much as Einstein (2, Insightful)

Anonymous Coward | about 9 months ago | (#45876087)

True. That should never have made it to the beta stage.

More importantly, a beta should be to get feedback, and aside from writing comments in articles that have nothing to do with it, I see no obvious feedback forum.

beta feedback (3, Informative)

Pastis (145655) | about 9 months ago | (#45876407)

on top left of the main site there's a link to http://www.surveymonkey.com/s/sdredesign [surveymonkey.com]

Re:beta feedback (1)

isorox (205688) | about 9 months ago | (#45877125)

on top left of the main site there's a link to

http://www.surveymonkey.com/s/sdredesign [surveymonkey.com]

Oh yes, with such unbiased options as:

How do you like the look and feel of Slashdot Redesign compared with the classic Slashdot site (www.slashdot.org)?
Significantly better
Better
About the same
Not as good.

Which leads to "Well many [2] of our readers thought the site was significantly better, but the worst response was it wasn't quite as good as the old one"

Re:beta feedback (1)

Virtucon (127420) | about 9 months ago | (#45878027)

It's an imperfect system but it's still a system.

Re:If only /. beta was tested as much as Einstein (0)

Anonymous Coward | about 9 months ago | (#45877421)

Don't confuse beta with alpha please.

I quite like it (1)

dominux (731134) | about 9 months ago | (#45877041)

much more modern looking, it works fine for me. I can reply to stuff, understand the threading and generally it works just great.

Will be interesting ... (4, Interesting)

TrollstonButterbeans (2914995) | about 9 months ago | (#45875801)

n-body calculations are hard enough with Newtonian physics. The "Einsteinian physics" calculations must be a bit maddening, but at least they have found a star system to test it out.

Re:Will be interesting ... (0)

Anonymous Coward | about 9 months ago | (#45875863)

n-body calculations are hard enough with Newtonian physics. The "Einsteinian physics" calculations must be a bit maddening, but at least they have found a star system to test it out.

Meh, just simulate it. No need to solve the equations, and simulating it isn't very hard. We have computers now, they are good at this.

Re:Will be interesting ... (4, Insightful)

Anonymous Coward | about 9 months ago | (#45875915)

Meh, just simulate it. No need to solve the equations, and simulating it isn't very hard. We have computers now, they are good at this.

But how do you know if your simulation is correct?

Anyone could easily write a sim that has three stars and they all coexist, happily passing through each other or something ridiculous. The point here is that we can see if the Theory and any simulations match the real world.

Re:Will be interesting ... (1)

Anonymous Coward | about 9 months ago | (#45876095)

Yes, you compare the simulation to the observations. I suppose I didn't explicitly state that, but I assumed it was obvious. My point is theres no need for hard math, just see if a simulation matches reality. N-body simulation is trivial: I wrote one in middle school. A relativistic one is only slightly harder. This one is likley gonna need tidal forces and other tedium too, but thats another issue.

My main point was "n-body calculations are hard enough with Newtonian physics. The "Einsteinian physics" calculations must be a bit maddening" is a pretty stupid thing to say. Newtonian N-body simulation is trivial (only trying to solve it explicitly is hard.) "Einsteinian physics" isn't a thing, the term here is "General Relativity", and its not really very maddening. Its a few extra terms of beautiful math in the simulator. Computers make such simulations very easy, even childs play (I played with them as a child anyway...). The entire challenge here is in getting the observations (which are a fantastic btw), not the math.

Re:Will be interesting ... (0)

Anonymous Coward | about 9 months ago | (#45876153)

What observations of a three-body model do we have? The last time I checked the universe has more than three bodies in it, one of them being YOUR MOM!

Re:Will be interesting ... (1)

Anonymous Coward | about 9 months ago | (#45876695)

His point is that it is easy to write some n-body simulation, but it is much harder to write one that gives correct results, and to prove that it follows the theory. The one you wrote in middle school probably didn't give correct results, or could you reproduce for example constant orbits in a two body problem?
If you compare your simulation result to reality and you do not know if your simulation follows the theory you can not conclude anything.

Re:Will be interesting ... (0)

gnasher719 (869701) | about 9 months ago | (#45877191)

His point is that it is easy to write some n-body simulation, but it is much harder to write one that gives correct results, and to prove that it follows the theory. The one you wrote in middle school probably didn't give correct results, or could you reproduce for example constant orbits in a two body problem?

It's just a bloody simple system of differential equations. n bodies, each has a location (3 coordinates) and a speed vector (3 coordinates), so you have six equations. The speed is obviously the derivative of the location, and the theory gives you the equation to calculate the derivative of the speed. Look up Fehlberg or "Adaptive Runge-Kutta-Fehlberg" and you are there.

Re:Will be interesting ... (4, Insightful)

dotancohen (1015143) | about 9 months ago | (#45877353)

It's just a bloody simple system of differential equations. n bodies, each has a location (3 coordinates) and a speed vector (3 coordinates), so you have six equations. The speed is obviously the derivative of the location, and the theory gives you the equation to calculate the derivative of the speed. Look up Fehlberg or "Adaptive Runge-Kutta-Fehlberg" and you are there.

That's Newton.

With relativity things get hard, quick. Both time (thus, speed) and space (thus, speed and distance) dilate, mass changes (thus, the attractive forces between bodies and thus their acceleration, and thus their speed, and thus their location), and some other oddities.

Re:Will be interesting ... (0)

Anonymous Coward | about 9 months ago | (#45877515)

In boring situations, orbits in general relativity can be solved treating bodies as point particles. But in more interesting situations, whether involving precision measurements of satellites near Earth or involving compact massive bodies like neutron stars and black holes, the distribution of matter affects the results, and you can't take that approximation. There are already some problems and difficulties with solving just two bodies that are close enough or have strong enough interaction, because the full Einstein field equation is nonlinear, and it takes some effort to develop solvers that will actually converge. Try just writing a "one body" simulation of GR sometime, where you have a single large body with analytic solution and track the orbit of a small probe particle. It isn't that hard, and anyone who's had an intro to GR class could do it (if not find analytic solutions in some cases), but it is harder than just copy pasting a numeric integrator because the non-Euclidian geometry in GR can be a pain in the ass.

Re:Will be interesting ... (1)

HiThere (15173) | about 9 months ago | (#45881305)

That will give the wrong answer. The reason is step size. Remember the relative positions are constantly changing, except for certain special cases.

FWIW, professional astronomers can't do an accurate model of the solar sysstem. The can do one that's "almost correct", but that's not the same. And the solar system can be handled with Newtonian mechanics. Once you bring in pulsars emitting gravity waves...Yi!

P.S.: IIRC, the best models of the solar system can't predict on which side of the sun the earth will be located in exactly 100 million years from now. When you project further, the results get fuzzier.

OTOH, in this case we're only looking at three stars. We're ignoring minor dust like planets. So it's guaranteed that we won't be able to find really minor effects. But, IIRC, the expectation is that emission of gravity waves will cause the orbits to decay more rapidly. (And I seem to also recall that in a previous case that effect wasn't found, but they weren't sure their observations were sensitive enough to have found it.) So this could be really interesting.

Please note: I am not an astronomer of any variety. I just read populaarizations. So I can't point you to any original sources any better than Google could.

Re:Will be interesting ... (2)

fisted (2295862) | about 9 months ago | (#45876111)

And how do you know if your equations are correct?

Anyone could easily write an equation that equates the living hell out of the three bodies, putting them in some absurd relation to each other. Does it say anything about reality? Nah.

Re:Will be interesting ... (3, Informative)

mangu (126918) | about 9 months ago | (#45877013)

And how do you know if your equations are correct?

That's the whole point raised by TFA. You know your equations are correct if the results of the simulation agrees with the results of the observation.

This system offers an unprecedented way to check how much does model general relativity fit the actual universe.

It's all in TFA, but I suppose reading it breaks the slashdot rules. Since we have three stars that are much more massive than any other three body system observed before, we can make measurements of the effects of gravitation with more precision, because the effects of those three stars on each other are so much bigger than the perturbations from other masses.

Re:Will be interesting ... (1)

gstoddart (321705) | about 9 months ago | (#45877351)

Anyone could easily write an equation that equates the living hell out of the three bodies, putting them in some absurd relation to each other. Does it say anything about reality? Nah.

Doesn't it come down to "do your equations match reality?"

I'm pretty sure they're not just going to come up with an equation and say "see, done" -- they're going to make sure it matches up with what we observe.

You know, empirically either validate or refute the equations.

Re:Will be interesting ... (1)

fisted (2295862) | about 9 months ago | (#45878727)

How does that not apply to simulation? Or didn't you bother to read the thread?

Re:Will be interesting ... (1)

gstoddart (321705) | about 9 months ago | (#45878763)

I did, but it's one thing to have calculations, it's another thing to run a simulation, and it's yet another thing to be able to compare those to an actual system and see if your results stack up.

As I understood this, this is the first time someone will be able to actually validate the equations and simulations against something real.

Re:Will be interesting ... (0)

Anonymous Coward | about 9 months ago | (#45881801)

Why would you go to the effort of creating a simulation, when you could just run the equations on a couple of points?

Remember; the simulation will need to have the capability to run the equations - to feed the simulation.

What the fuck do you think a simulation is if it isn't calculating the equations?

Why would creating a simulation be easier; than running the equations a couple of times and comparing those numbers to reality?

CHRIST.

Your NBody problem for example.

Why would you create an N-Body simulator to test Newtons equations, when you could run the numbers, calculate that after 10 seconds the body should end up 10 meters in a specific direction.

Look at the body; wait ten seconds; look again.

Why is your stupid ass simulation idea any better than running the fucking numbers? Besides; you have to know the hldgajkl;dgahkl

I give up.

Re:Will be interesting ... (1)

Nemyst (1383049) | about 9 months ago | (#45876097)

I can't even begin to imagine the mathematics required, but I'm fairly sure that when you start talking about general relativity you need to drop Euclidean space. Then you can enjoy tensors. And geodesics (ie. the path that a free-moving object would follow, which no longer is necessarily a line). And so much more stuff I've forgotten and have no wish to remember.

I still have nightmares from my Electromagnetism III class.

Re:Will be interesting ... (1)

Anonymous Coward | about 9 months ago | (#45876377)

... and now we integrate over the surface of this piece of chicken...

Re:Will be interesting ... (0)

Anonymous Coward | about 9 months ago | (#45876639)

... and now we integrate over the surface of this piece of chicken...

Assuming that the chicken is point shaped; finding the surface of a partial point seems more like a philosophical problem than a math one. (Yes, XKCD is wrong, math is just applied philosophy.)

Re:Will be interesting ... (1)

el jocko del oeste (2450190) | about 9 months ago | (#45878803)

It's much easier if you just assume a spherical chicken...

Re:Will be interesting ... (1)

jabuzz (182671) | about 9 months ago | (#45877601)

n-body calculations where n>3 are all simulations. Anyone coming up with a mathematical solution to such a system is in line for a Nobel prize.

The trick is to remember there are no real three body systems in the entire universe...

Re:Will be interesting ... (1)

interkin3tic (1469267) | about 9 months ago | (#45880219)

n-body calculations where n>3 are all simulations.

I was going to say, I can solve plenty of N-body calculations where N = zero.

(I think anyway. I'm a biologist not a mathologist. Maybe N = zero is a real thing that isn't simply "zero." If so, I sincerely apologize and accept my punishment.)

Re:Will be interesting ... (0)

Anonymous Coward | about 9 months ago | (#45881661)

N >= 3.

Re:Will be interesting ... (0)

Anonymous Coward | about 9 months ago | (#45880301)

No, it's only hard because of border conditions. If we assume those stars never hit each other, which is fine in this case, the math becomes much more simple.

No text (0)

Anonymous Coward | about 9 months ago | (#45875829)

You're welcome, Earthlings...

Awesome (0)

Anonymous Coward | about 9 months ago | (#45875859)

Exploring space from our computer chairs and with our mathematical models! Awesome. Imagine if we had complete nutcases in charge of science who'd insist we have to send *people* to the pulsar to explore it?

"A violation would be a complete revolution." (4, Interesting)

VortexCortex (1117377) | about 9 months ago | (#45875893)

The summary is light on any details, so here:

The distinctive new system opens the way for testing a concept behind general relativity known as the equivalence principle, which relates two different conceptions of mass. An object's inertial mass quantifies how it resists pushing or pulling: It's easier to start a stroller rolling than a car because the stroller has less inertial mass. A thing's gravitational mass determines how much a gravitational field pulls on it: A barbell is heavier than a feather because it has more gravitational mass.

The simplest version of the equivalence principle says inertial mass and gravitational mass are equal. It explains why ordinary objects like baseballs and bricks fall to Earth at the same rate regardless of their mass—as legend claims Galileo showed by dropping heavier and lighter balls from the Leaning Tower of Pisa.

The strong equivalence principle takes things an important step further. According to Einstein's famous equation, E = mc2, energy equals mass. So an object or system's mass can be generated by the energy in the gravitational fields within the system itself. The strong equivalence principle states that even if one includes mass generated through such "self-gravitation," gravitational and inertial mass are still equal. ...
By tracking the system's evolution, Ransom and colleagues should be able to tell whether either the inner white dwarf or the pulsar falls faster toward the outer white dwarf and test strong equivalence about 100 times as precisely as before, Damour says.

"Gravitational Field"... space-time curvature "field"? Uhm, "gravitational mass" vs "inertial mass" equivalence... "explains why" o_O? Shh! The astrophysicists are over. Don't mention the Higgs!

In all seriousness, we know damn well Einstein's equations are simply better approximations / explanations than Newton's approximations are -- It's only a matter of time before we prove them "wrong" (but still damn good and useful approximations, like Newton's) -- We just need some elusive experimental evidence to prove it, and this could be it due to the large gravitational coefficients and a steady measurement scale provided in the pulsar. That is, unless Einstein's approximation turns out to be more accurate than our observations of this system. It shouldn't be any more of a "revolution", as TFA states, if the observations prove to be in violation of the equations: We should be trying to find better equations anyway thanks to that whole Standard Model thing, and we are. Physics seems to goes through these periods where a bunch of new theories explain various things to a precision, the precision is surpassed in observations, and then someone like Newton, Einstein, Feynman, Hawking, etc. comes along and presents elegant / unifying equations to explain the disparate pieces better. Looks like we're still in the middle of the very important prove old-theories "wrong" (read: inaccurate, conflicting with some observations) and scratch our head over tests for new hypotheses to fit more accurate measurements stage.

Re:"A violation would be a complete revolution." (0)

BringsApples (3418089) | about 9 months ago | (#45876061)

In all seriousness, I know nothing of this. You seem like maybe you have a handle on it, and that's great. What I have to ask is, what in the hell is vortexcortex.com?

Re: "A violation would be a complete revolution." (1)

Anonymous Coward | about 9 months ago | (#45876079)

vortexcortex.com is obviously a domain name. Duh.

Re: "A violation would be a complete revolution." (0)

Anonymous Coward | about 9 months ago | (#45876125)

+1 Informative

Re:"A violation would be a complete revolution." (5, Insightful)

dcollins (135727) | about 9 months ago | (#45876099)

Yeah, that sort of sounds like a bunch of late-night-I've-got-the-munchies BS.

FTA: "Paulo Freire, a radio astronomer at the Max Planck Institute for Radio Astronomy in Bonn, Germany... says a violation would be 'a complete revolution.'"

No offense, but I'm going to trust the astronomer at the world-renowned scientific institute over the indie-game artist on this one.

Re:"A violation would be a complete revolution." (0)

Anonymous Coward | about 9 months ago | (#45876353)

Yeah, that sort of sounds like a bunch of late-night-I've-got-the-munchies BS.

FTA: "Paulo Freire, a radio astronomer at the Max Planck Institute for Radio Astronomy in Bonn, Germany... says a violation would be 'a complete revolution.'"

No offense, but I'm going to trust the astronomer at the world-renowned scientific institute over the indie-game artist on this one.

Exactly. Anyone who have read some popular science books can sprout smart ass comments like "we know damn well theory X is just an approximation and will be proven wrong eventually..." etc etc.

The billion dollar question, of course, is HOW it could be wrong, and the trillion dollar question is WHAT is the (more) correct theory.

With GR putting gravity in terms of spacetime curvature, any difference between inertial mass and gravitational mass would mean the *entire* picture is wrong! That's the beauty of GR, you *cannot* just fiddle or fine-tune some constant to account any such difference. The entire theory is more or less self-contained with very little room for arbitrary changes (the only one left for fiddling, of course, is the famous cosmological constant). You want to change anything, you probably got to ditch the idea that gravity comes from spacetime curvation, or that "spacetime" really have a very different meaning on some very small scale. And THAT was what "a complete revolution" meant.

Re:"A violation would be a complete revolution." (0)

Anonymous Coward | about 9 months ago | (#45877005)

Bah, a complete revolution is nothing special. The earth does it every year around the sun!

Re:"A violation would be a complete revolution." (0)

Anonymous Coward | about 9 months ago | (#45877081)

and once a day about its own axis.

Re:"A violation would be a complete revolution." (0)

Anonymous Coward | about 9 months ago | (#45877199)

Almost. Note that the number of times the earth rotates on its axis in a year is not the same as the number of days in a year.

Re:"A violation would be a complete revolution." (1)

interkin3tic (1469267) | about 9 months ago | (#45880253)

VortexCortex wasn't appealing to his authority though. He provided reasoning beyond "listen to me, I know what I'm talking about."

I'd have to read TFA (shudder) to see if the astronomer backed up his statement, but an astronomer simply saying "This is revolutionary!" would be less convincing than what VortexCortex posted if that's all there was.

Re:"A violation would be a complete revolution." (2)

Nemyst (1383049) | about 9 months ago | (#45876123)

It would be a revolution in the sense that it would be, as far as I know, the first time general relativity is shown wrong factually. This is different from the quantum mechanics/relativity problem, which is that the two are not compatible (so we know something's missing, but we don't know where).

Re:"A violation would be a complete revolution." (2)

Guy Harris (3803) | about 9 months ago | (#45876149)

That is, unless Einstein's approximation turns out to be more accurate than our observations of this system.

Err, umm, "accurate", when it comes to predictions of scientific theories, means "closely matches the observations", so a theory can only be "more accurate than our observations of this system" if the observations in question are wrong and subsequent observations, determined to be (more) correct, are better matched by the predictions of the theory. Is that what you mean here?

Re:"A violation would be a complete revolution." (0)

Anonymous Coward | about 9 months ago | (#45876437)

The observations may have an error bar larger than the differences between predictions from competing theories.

Re:"A violation would be a complete revolution." (0)

Anonymous Coward | about 9 months ago | (#45876919)

Physics seems to goes through these periods where a bunch of new theories explain various things to a precision, the precision is surpassed in observations, and then someone like Newton, Einstein, Feynman, Hawking, etc. comes along and presents elegant / unifying equations to explain the disparate pieces better.

Sounds a bit naive to me. Einstein's equations are not "elegant". What he did was not finding "better equations", but rather a world view where time and space work without a central reference frame. He then tailored the equations to fit. Better mathematicians worked on making the equations more elegant later on.

The math was harder to him, but he knew where he wanted to take it.

Re:"A violation would be a complete revolution." (1)

Grey Geezer (2699315) | about 9 months ago | (#45877263)

Wait just a nanosecond. I'm just a self educated layman, but didn't Einstein come up with an explanation for how gravity works (mass distorts space-time)? Whereas Newton believed gravity worked because...what? Einstein did a lot more than just come up with a better equation didn't he? Heck, even the concept of space-time is very important concept, that, while illustrated through equations, took us far beyond the Newtonian understanding of the Cosmos. It's much more than just refining the math. Don't you think?

Re:"A violation would be a complete revolution." (1)

david_thornley (598059) | about 9 months ago | (#45881219)

Actually, AFAIK we don't know that Einstein's equations are wrong at all. That's a surmise. (Yes, there's something wrong somewhere, but it may not be GR.) It may well be true, and we won't know until we find discrepancies. That's what this astronomical research is for. Without discrepancies, about all we can say is that GR accounts for the observed facts and is mathematically elegant, and looking for new equations is speculative at best.

Delicious (4, Funny)

jones_supa (887896) | about 9 months ago | (#45876003)

In a cosmic coup, astronomers have found a celestial beacon

Mmm...cosmic soup with bacon!

Re:Delicious (0)

Anonymous Coward | about 9 months ago | (#45876129)

Is celestial bacon anything like Canadian bacon?

Re:Delicious (1)

Jason Levine (196982) | about 9 months ago | (#45877491)

Everything in celestial terms is much, much bigger. Therefore, I'd expect celestial bacon to be five light years across and twenty five light years long.

Re:Delicious (1)

Dareth (47614) | about 9 months ago | (#45877525)

You don't know what you are talking aboot eh!?!

Is (1)

Impy the Impiuos Imp (442658) | about 9 months ago | (#45876147)

Ok, help my layman ass out here. IIRC, according to Einstein, acceleration and gravity aren't just similar phenomena, but are the exact same phenomena, and, since you are always travelling at c through the combined spacetime continuum, which gravity warps, the gravitational pull is you actually accelerating through this warped spacetime.

That seems way too freaking cool to fail at some umpteenth decimal.

No (1)

Anonymous Coward | about 9 months ago | (#45876261)

... since you are always travelling at c ...

Light travels at c in a vacuum and anything with mass does not. Be wary of anyone who tells you otherwise.

(I'm a physicist)

Re:No (0)

Anonymous Coward | about 9 months ago | (#45877059)

He almost certainly was (still incorrectly) thinking that we are travelling with speed c through spacetime. That's a common error based on the fact that the tangent vector on the proper-time parameterised world line, known as four-velocity, has the unit of a velocity and the length c. The fact that the four-velocity is not a velocity in spacetime in the same way the three-velocity is a velocity in space is lost on them. Of course the length of the tangent vector just tells you about the relation of proper length (in the relativistic case, proper time times c) to the parameterisation chosen for the line (proper time). Indeed, the vector length only has the unit of time because of the inconsistency of using length units for coordinate time (c*t), but time units for proper time (tau, not c*tau).

Unfortunately it is rarely explicitly said that for the four-velocity, it is the direction that has the velocity information, not the length.

(I'm also a physicist)

Re:No (1)

Impy the Impiuos Imp (442658) | about 9 months ago | (#45879827)

So...are acceleration and gravity the same phenomenon under relativity?

Re:No (0)

Anonymous Coward | about 9 months ago | (#45880245)

Their effects are locally indistinguishable (e.g. if you are inside a space ship with no windows and the ship is much smaller than any variations in gravity, you can't tell if you are accelerating or hanging from a rope in a gravitational field), but they are in the end still different effects when you can look out at the universe and see where mass is located.

Re:Is (1)

hutsell (1228828) | about 9 months ago | (#45876285)

Ok, help my layman ass out here. IIRC, according to Einstein, acceleration and gravity aren't just similar phenomena, but are the exact same phenomena, and, since you are always travelling at c through the combined spacetime continuum, which gravity warps, the gravitational pull is you actually accelerating through this warped spacetime.

That seems way too freaking cool to fail at some umpteenth decimal.

I've always found the feeling associated with thinking about the Principle of Equivalence to be exquisite — wistfully thinking something beautiful would be lost if (or when) it was disproven.

Heilig Götterdämmerung! (-1)

Anonymous Coward | about 9 months ago | (#45876163)

Again with the Relativity. We have another chance to invalidate this Einstein's jewish Science.

Re:Heilig Götterdämmerung! (0)

Anonymous Coward | about 9 months ago | (#45876333)

Einstein's Italian science, you mean.

http://en.wikipedia.org/wiki/Olinto_De_Pretto [wikipedia.org]

Or (1)

justthinkit (954982) | about 9 months ago | (#45877845)

Einstein's French [wikipedia.org] science.

It's Ether time (1)

justthinkit (954982) | about 9 months ago | (#45878167)

Since De Pretto [wikipedia.org] and Preston [wikipedia.org] and Poincare [wikipedia.org] and Newton [wikipedia.org] all were ether advocates, isn't it about time we try some ether theories once again?

Einstein (0)

Anonymous Coward | about 9 months ago | (#45876225)

It's too bad Einstein isn't around to help out with this. I am certain he would be a great asset.

Re:Einstein (0)

Anonymous Coward | about 9 months ago | (#45876331)

After a point, neural plasticity dooms us mere mortals to being less-than-useful for making new discoveries. Even the best pass and make room for you young whippersnappers.

gravitational relativity (0)

Anonymous Coward | about 9 months ago | (#45876229)

I would like to point out that only gravitational relativity has been "proven", and only with atomic decay.

The standard model itself starts to have more in common with religion than real science once you dig into it. I suppose the LHC could be thought of as a billion dollar temple. Last I checked, math isn't a substitute for actual observations, yet the standard model is presented as fact.

Re:gravitational relativity (0)

Anonymous Coward | about 9 months ago | (#45876431)

Huh?

The standard model (quarks etc.) is based on observation. Sure, the Higgs particle was predicted by math and theory, but not accepted until they found & observed it.

Re:gravitational relativity (1)

HiThere (15173) | about 9 months ago | (#45881695)

He's probably insisting on a more direct form of observation, even though he actually knows this is impossible. (Well, perhaps not, if the new lens design that allows one to see things fractions of a wave length long can be built at the right wave length. I've got my doubts...and even then the wavelength would be too short to see directly.)

OTOH, I'm also not very pleases with the quality of the evidence that we need to deal with, and would like something a lot less indirect. But right now that's the best we can do. So we are only "statistically certain" that certain observations mean what we think they mean. The statistics are conseervative enough that we can place a great deal of reliance on them, but...

Yet again, even direct physical observation of things of the appropriate size and opacity can't really be trusted, as was proved by experiments where a guy was stabbed with a banana, or a guy wandered through a basket ball game wearing a gorilla suit. (The cameras saw him, but very few of the observers did. They were too busy counting baskets.)

So I understand people being dissatisfied by "statistical certainty", but really, it can be better than eye-witness observation...at least unless that "eye-witness observation" is backed up by a camera.

Re:gravitational relativity (1)

ubergeek2009 (1475007) | about 9 months ago | (#45876563)

The only difference between physics and religion though is the fact that the 'temple' built to it is there to test to see if predictions made by the standard model are in fact correct, or if the theory needs revision. You will not see anything along those lines in a religion.

Re:gravitational relativity (0)

Anonymous Coward | about 9 months ago | (#45877101)

The only difference between physics and religion

That and the weapons physicists create actually work. For better or worse.

Re:gravitational relativity (1)

mcgrew (92797) | about 9 months ago | (#45877307)

The only difference between physics and religion...

There is nothing whatever that physics and religion have in common. Physics is the study of the physical universe, religion is not about the physical universe at all.

Re:gravitational relativity (0)

Anonymous Coward | about 9 months ago | (#45880839)

To a laymen there is very little difference. Both make wild claims about the nature of existence and both offer little if any concrete proof... keeping in mind that esoteric mathematical models do not equate to concrete proof for most people... they don't understand them, can't relate to them, don't even know a single person who has a clue about them. So to the average person, much of physics is a mystery they have to take on faith, just as much of religion is a mystery they take on faith.

Re:gravitational relativity (0)

Anonymous Coward | about 9 months ago | (#45877541)

Well, not just atomic decay, but precision clock measurements directly observing time dilation from motion and gravitational potential.... and deviations of orbits of planets from Newtonian gravity that are accurately explained by GR... and accurate measurements of the bending of star light, space probe signals, and deep space light ... oh, and spin down measurements of pulsars and orbiting compact massive objects ... and gravity probe B... and the Shapiro delay... and not even getting into cosmological results.

Re:gravitational relativity (1)

HiThere (15173) | about 9 months ago | (#45881753)

Sorry, but though the claim was made General Relativity didn't predict the correct deviation of Mercury's orbit. The key turned out to be the flattening of the sun at the poles. (I think once that was taken into account, General Relativity gave a better answer than Newton, but the Newtonian answer was good enough that it wouldn't have been noticed originally.)

creation; no straight lines or right angles (0)

Anonymous Coward | about 9 months ago | (#45876541)

resistance is futile. free the innocent stem cells

Re:creation; no straight lines or right angles (0)

Anonymous Coward | about 9 months ago | (#45878211)

Crystal lattices provide perfectly straight lines. There are numerous examples of right angles in nature. You rarely see a 90 degree corner in nature as they are mechanically weaker than a curved transition, but they certainly do exist in nature.

I have no idea where this claim of no straight lines or right angles comes from, but it's certainly not from anyone who knows much about nature.

Re:creation; no straight lines or right angles (0)

Anonymous Coward | about 9 months ago | (#45881323)

Of course you can create a perfectly straight line with any given two points, or for a particle traveling without interaction with other fields and particles, but crystal lattices are far from perfect straight lines, unless you had a pure crystal at absolute zero without any external stresses applied upon it.

ether is the key (0)

pacija (2566467) | about 9 months ago | (#45876755)

Einstein's theory is completely incorrect. Famous equation E=mc2 is incorrect as well. "The proof" of formula's accuracy is based upon experimental fact that derrivative of energy released in atomic fusion (dE) equals derrivative of product of mass and speed of light squared (dmc2). However, _integral_ of this equation equals E=mc2+C, with C being a constant, so Einstein's formula would be correct only if mentioned constant equals zero. Contemporary theorethical physics is meeting a dead end mainly because of incorrect assumption that interstellar space is empty, meaning its energy equals absolute zero (constant C equals zero in Einstein's equation). In reality, interstellar space is filled with vast energy and matter of great density, whereas mass represents effect of local changes in basic density and basic energy. Much more about this, including calculated gravitational constant, can be read online in my book: http://www.vasiona.rs/ [vasiona.rs]

Re:ether is the key (1)

sjwt (161428) | about 9 months ago | (#45876831)

I'm sorry, I cant tell if your a targeted spambot or serious.

serious (1)

pacija (2566467) | about 9 months ago | (#45877089)

I am serious and open for discussion.

Re:serious (0)

Anonymous Coward | about 9 months ago | (#45877583)

Why so serious?

Re:serious (0)

Anonymous Coward | about 9 months ago | (#45877865)

Sounds like a spambot. Will your website try to sell us pills that don't work and that we don't need?

Besides, since C is a constant, why is the integral of m(C^2) not 0.5*(C^2)*(m^2) + c? (where c is a different constant)

Note that constant c has units of J*kg ( (velocity^2 * mass^2), i.e. (m/s)^2 * (kg^2) ), which is different than energy.
Also note that m is the rest mass.
This is using the basic formula y=mx+b, setting b to 0 and m to C^2.

You should also note that (completely incorrect) != (not completely correct). This may be a translation issue, but the way you phrased it is not accurate.

Re:ether is the key (1)

cusco (717999) | about 9 months ago | (#45881541)

It's the Electric Universe folderal again, I think. Better than arguing with the people who believe in 'morphic fields', but not much.

Re:ether is the key (0)

Anonymous Coward | about 9 months ago | (#45877569)

E=mc^2 comes from the original propose of special relativity that speed of light is constant in all frames, which yields the relativistic mass such that an accelerating object only approaches c in every frame, which then yields the concept of a rest energy that must be subtracted out to get the classical kinetic energy in low velocity approximations. No integration constant is required or even comes up. The idea that space can have an inherent energy does not contradict this or support this, and is an independent concept that actually works quite well with relativity. Special relativity wouldn't care, and general relativity can easily work with such a situation, and in fact is used as such in cosmology a lot.

Re:ether is the key (0)

Anonymous Coward | about 9 months ago | (#45877883)

You can derive E=mc^2 using just algebra and the Lorentz transformation, which itself is derived from Maxwell's equations. Experimental validation comes from a large variety of nuclear reactions (including fusion, but also fission and decay processes), matter-antimatter annihilation, pair production, and particle production in particle accelerators.

Re:ether is the key (1)

HiThere (15173) | about 9 months ago | (#45881879)

IIRC though (this is several decades ago) you only get the simplified form by dropping higher order terms. There was a good reason to do so (IIRC they were *extremely* small in value), but it does mean that it's an approximation. However, since even the deviation of Einsteinian theory from Newtonian is difficult to detect, I expect that the corrected version would differ from the Einsteinian version to such a slight degree that it would still be impossible to detect. And (again, IIRC) there was an infinite series of such terms, each (nearly) infinitesimally small when compared to the prior term. So you couldn't find the exact value no matter what you did. And the length of the calcularions would more than double for each term you added.

Re:ether is the key (1)

justthinkit (954982) | about 9 months ago | (#45878327)

Hello Sava,

I completely agree with you about the ether, and in fact I just posted such a comment [slashdot.org] before I read your comment.

I look forward to reading more about your theory and humbly offer my own [just-think-it.com] for your consideration.

Best,

Floyd

'It's almost made to order.'" (1)

bob_jordan (39836) | about 9 months ago | (#45877109)

Whose to say it wasn't? Maybe some advanced civilisation built it to test just this principal. Maybe we are simply looking over the shoulder of someone else's work. How do they correctly reference that in the eventual paper? :-)

Bob.

Re:'It's almost made to order.'" (0)

Anonymous Coward | about 9 months ago | (#45879317)

Maybe the belt is made of your atrocious grammar and terrible spelling?

Re:'It's almost made to order.'" (0)

Anonymous Coward | about 9 months ago | (#45880099)

Except the belt is an attractive force, not a repulsive one.

can someone explain this? (1)

slashmydots (2189826) | about 9 months ago | (#45879459)

The article suggests that E=MC^2 does not solely mean antimatter and matter collide and tada you get energy or that a hadron collide can convert energy into matter. They claim that mass that is moving contains energy and thus generates more mass/gravity. I certainly don't remember learning THAT in school. I know if you're heavy and moving fast, more time will occur throughout the mass but they didn't say gravity would increase. Then they refer to "self gravitation" as in the object pulling in on itself as in the expected gravitational field of anything with mass larger than a singularity, which IS inline with normal physics. Can anyone verify that they're actually correct on that other point or is it as nonsensical as it sounds?

Re:can someone explain this? (1)

bunratty (545641) | about 9 months ago | (#45879695)

The equation e=mc^2 means that matter and energy are the same thing, just in different forms. When you move, you gain kinetic energy and therefore gain in mass and therefore exert more gravity on other bodies. The equation just gives a way of converting units of mass to units of energy. It's just like converting nanometers to kilometers -- both units represent the same kind of quantity (length), just different amounts.

There is a God after all? (1)

lars_stefan_axelsson (236283) | about 9 months ago | (#45880699)

"Made to order?" Hmm, so the creationists are right after all. There is a creator and he clearly likes science...

Could have been worse I guess.

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