Is the Earth in a Vortex of Space-Time? 249
da6d writes "Apparently, we'll soon know for sure.... NASA has announced in an article that 'A NASA/Stanford physics experiment called Gravity Probe B (GP-B) recently finished a year of gathering science data in Earth orbit. The results, which will take another year to analyze, should reveal the shape of space-time around Earth--and, possibly, the vortex.'" More from the article: "If Earth were stationary, that would be the end of the story. But Earth is not stationary. Our planet spins, and the spin should twist the dimple, slightly, pulling it around into a 4-dimensional swirl. This is what GP-B went to space to check."
Space (Score:5, Funny)
Re:Space (Score:2, Funny)
A time, cube perhaps? (Score:4, Funny)
http://www.timecube.com/ [timecube.com]
uhh (Score:5, Funny)
Are you on crack!? The earth is stationary. It is the sun that's moving.
Re:uhh (Score:5, Funny)
Are you on crack!? The earth is stationary. It is the sun that's moving.
It's the fact that it's flat that gives it the illusion of motion.
Re:uhh (Score:2, Funny)
The crack probably helps.
Re:uhh (Score:5, Funny)
No, it's flat because it's stationery, duh!
Re:uhh (Score:3, Funny)
Who says stationery have to be flat!?
My new Sharpie has some sweet curves.
And don't even get me started on my red stapler...
Re:uhh (Score:5, Funny)
No. The Earth is too complex to have just ended up flat with the sun spinning around it. A higher power must have had a guiding hand. So we should instruct kids on the Intelligent Flat Earth Design Theory over the Newtonian-Einstienian theories of gravity, which are after all, completely unprovable.
Re:uhh (Score:2)
The problem with ID is that they are not looking for supporting evi
Re:uhh (Score:2)
You didn't even read "Darwin's Black Box", did you? Loon.
Re: (Score:2)
shush (Score:2)
Re:uhh (Score:2)
Re:Educated cubeless stupid, you are stupid (Score:2)
Comment removed (Score:5, Interesting)
Re:uhh (Score:5, Insightful)
One of the exact solutions to the Einstein field equations is a decent assumption for the Earth's (or anything approximately spherical which is not moving relativistically) gravitational field. The curvature of space-time is greater the closer to the center of the massive body. A light ray travelling some distance from the massive body will be deflected from a "straight line" (which is hard to define in curved space).
If you are taking the view that you start rotating the rest of the universe around us, then it is equivalent to having your coordinate system spin around the massive body (well, there is nothing besides the massive body in the universe I am imagining). Physically, light will follow the same path as it did before, since all you have done is redefine the coordinate system, which does not change physics!
Now instead, consider spinning the Earth, instead of the coordinate system. The matter making up the earth now has more energy-momentum (the magnitude of which is a physical quantity which can be measured independent of reference frame, if your frame is freely-falling). Energy-momentum is what causes space-time to curve, so a light ray travelling the same distance from the earth will be deflected by a larger amount, since space will be more curved.
Re:uhh (Score:2, Interesting)
Re:uhh (Score:2)
It means that you can use it to write a nice letter to a friend.
Re:uhh (Score:2)
It was a very interesting lecture, but at the end of it, during the Q&A part, one of the professors asked what amounted basically to this: "well, it's good and well that NASA created this purpose built satelite, but wasn't there recently an existin
Re:uhh (Score:2)
That said, even if you're trapped in the 1500s and want to pretend that the
Re: (Score:2)
Re:uhh (Score:2, Funny)
So... (Score:2, Funny)
Re:So... (Score:4, Funny)
No, but if there is a sucking sound your job is being outsourced.
well at least (Score:3, Funny)
CH
Re:well at least (Score:4, Funny)
No, "Our planet spins, and the spin should twist the dimple, slightly" explains leap years, daylight savings time, and the previously inexplicable 1.42-minute-per-month gain on my employer's time clock.
"A three-sided vortex (once limited to the greater Bermuda area but in recent years expanded to be anchored at Crawford, TX, Washington, DC, and Baghdad due to depletion of the ozone layer) into which pour vast sums of the rest of the world's time and money" explains the Bermuda Triangle.
Re:well at least (Score:2, Interesting)
Re:well at least (Score:2)
It's all relative (Score:4, Funny)
I see they found that universal frame of reference they were looking for.
Re:It's all relative (Score:5, Informative)
Re:It's all relative (Score:5, Informative)
GP is needlessly complicated. All he needs to say is that spinning reference frames are not on the same footing as non-spinning ones. Stand on a merry-go-round with a toddler and film him trying to walk around and you'll see that there's definitely a difference between spinning frames and stationary ones. Also, you'll see a toddler fall over, which is always funny.
Re:It's all relative (Score:2)
Re:It's all relative (Score:5, Interesting)
Doesn't really apply to rotation.
If you're sealed inside a spaceship moving at constant velocity and cannot refer to the outside in any experiment, you have no way to determine what its velocity might be. There's no physical difference between 'stationary' and '0.999c', until you interact with something outside. Even then, you can still declare that you're stationary and that it is moving and the physics works out the same.
If, however, you're sealed inside a spaceship rotating with constant angular velocity, that's quite another matter. You'll know about the rotation, either by reference to gyroscopes if it's spinning very slowly, or by the fact that you seem to be stuck to the wall if it's spinning very quickly...
Re:It's all relative (Score:2)
Re:It's all relative (Score:2, Informative)
Re:It's all relative (Score:2)
Re:It's all relative (Score:3, Interesting)
Guy #1 pulls out and holds up a red laser. He shoots the beam. Because he's firing forward, the beam gets blue-shifted and heads up the hallway towards the front guy. A short while later, the front guy has a bunch of blue (ultraviolet? green? I'm too lazy to do the math right now) photons hit him. However, he's movi
Another dimension (Score:2, Funny)
On the bright side if we did get flushed through the vortex at least we would no longer be located in the unfashionable western edge of the galaxy.
Re:Another dimension (Score:3, Funny)
Who cares as long as the galactic water is spinning the right direction. If it's not we'll have to do something about that to make sure the Galaxy flushes correctly.
(Yes, I know it's a myth so don't go posting Wikipedia links or others telling me).
Whoa! (Score:4, Funny)
Re:Whoa! (Score:2)
Read the lyrics to Chemical Calisthenics [seeklyrics.com]. Or MUCH preferably, listen to them [apple.com].
Too much Star Trek... (Score:2)
Purple Nurple Probe (Score:5, Funny)
cool (Score:2, Funny)
Re:cool (Score:2)
Only this one, and in a teapot.
Just In Case (Score:4, Funny)
Funny link (Score:3, Interesting)
The engineering story (Score:5, Informative)
"The four gyro rotors are made of fused quartz, fabricated to an extreme level of material homogeneity and then ground to the near-absolute sphericity (Figure 1). The spheres are round to within 40 atomic layers, which is proportionally equivalent to an Earth-sized sphere with surface height variations of only 16 feet...."
"It's one thing to have a virtually perfect gyro rotor, but that alone does not provide the necessary performance for this experiment......The electric fields center the rotors to a few millionths of an inch. They did not perform the spinning up electrically, however. Instead, they directed a precise stream of helium gas, traveling at nearly Mach 1, at the rotors. It takes about half an hour for the rotor to reach full speed, and it loses less than 1% of this speed over 1000 years in the super-vacuum of the cavity."
Re:The engineering story (Score:2)
Neat (Score:5, Interesting)
Is there a difference between rotating reference frames and non-rotating reference frames because of the universe of matter around them, or is it self-generated? In other words, if we "removed" the entire universe except the rotating Earth, would rotation still have meaning? Could we still do an experiment and detect its rotation, or is that an artifact of the universe of matter around it that would vanish when it did? As far as I understand general relativity (and IANAP), it does not make a hypothesis one way or the other. Is the question meta-physical? Or is there some clever way to set up an experiment to actually tell?
Sigh - sometimes, I wish I was a physicist!
Re:Neat (Score:2)
I believe this phenomenon was observed much earlier by the Rossi X-ray Timing Explorer (RXTE). I think the author was Todd Strohmeyer (sp?), but I can be wrong in detail.
Re:Neat (Score:2)
It would still be simple. Try launching one rocket west, one rocket east. You'll pretty so
Re:Neat (Score:3, Interesting)
This experiment may help kill off one of the more interesting alternatives, John Moffat's asymmetric variant of GR. Moffat is a self-taught savant, now at the University of Waterloo's Perimeter Institute, iirc. He realized that Einstein's equations contained a symmetry condition that
Re:Neat (Score:2)
Re:Neat (Score:3, Interesting)
None of these two effects depends in any way on the surrounding matter, so I have a hard time imagining they'd go away if you remove
Re:Neat (Score:2)
However, Newtonian gravity plus special relativity does predict a gravitational analogue of magnetism. The parts of the rotating bodies moving at higher relative velocity experience more relative length contraction, thus appearing to be denser masses.
Welcome to Sector ZZ-plural-Z9-Alpha (Score:2)
Douglas Adams certainly was a hoopy frood.
grrr! screwed up even the title of my own post! (Score:2)
It's not the Earth, silly.... (Score:2)
Re:It's not the Earth, silly.... (Score:2)
Pretty much.... (Score:2)
Re:Pretty much.... (Score:3, Insightful)
Typical anti-Christian agenda (Score:2, Troll)
Atheistic [fixedearth.com] trash [geocentricity.com].
Re:Typical anti-Christian agenda (Score:2)
Re:Typical anti-Christian agenda (Score:2)
Actually, I was parodying the usual anti-science idiots I often see crawling around discussions of evolution. They are the ones who associate anything that disagrees with their literal Biblical interpretations as anti-Christian, not me.
Rudof Steiner said it 100 years ago (Score:4, Insightful)
This could be the proof of his statement.
Re:Albert Einstein said it 100 years ago (Score:3, Insightful)
Re:Albert Einstein said it 100 years ago (Score:2)
True, but I think you can even broaden this statement by saying that is just one of the simplyfing assumptions (unless there is a reason to believe otherwise) for any scientific work.
Anyway, having an idiotic Steiner reference modded up more than your post is a very sad day for
Have the eco-nuts and new-age-zealots finally overran this place!?
Re:Rudof Steiner said it 100 years ago (Score:2)
Re:Rudof Steiner said it 100 years ago (Score:2)
Please make it stop! (Score:2)
Technology moves on (Score:3, Interesting)
Einstein would probably have been surprised at this particular application of relativity.
Re:Technology moves on (Score:2, Informative)
Is the Earth in a Vortex of Space-Time? (Score:2)
The 'vortex' has been closed... (Score:2)
Another act of the FSM (Score:2)
Just as the bones of dinosaurs and the stars in the sky were placed by our noodly master, so is this great work of his doing.
Avast ye ignorant dogs! Worship ye great master and his wee midget. For he be a harsh mistress, and his noodly wrath shall send ye all down to Davey Jones's Locker!
Poor Tax Payers (Score:2, Interesting)
1. The experiment agrees with GR and NASA says that GR is right about frame dragging.
2. The experiment doesn't agree with GR and NASA says that it messed up and they'll ask the tax payers for a do over.
This experiment is not legitimate. If they get the result they expect, they'll accept the result. If they don't get the result they expect, they'll just say (rightly) that it was a flawed experiment. We won't get an
Did they issue a press release... (Score:2)
From the article: "First, though, there are a lot of data to analyze. Stay tuned."
They did! The whole press release was to tell us they haven't analyzed the data yet, and to stay tuned for the next press release...
Re:Stephen Hawkings (Score:2)
*That's what I think the linked article states, cuz.. uhh, I didn't read it.
You didn't have to RTFA to figure this one out, the summary itself states that it will take approximately a full year to analyze the data. Only once the data is analyzed will the vortex phenomona considered proven (or disproven, obviously).
Re:Stephen Hawkings (Score:5, Insightful)
Not so obvious. The word 'inconclusive' comes to mind.
Re:Stephen Hawkings (Score:5, Funny)
Not as often as the word 'hooters'.
-
Re:Stephen Hawkings (Score:2)
Not so obvious. The word 'inconclusive' comes to mind.
Well, if the theory predicts a certain effect of a certain magnitude, and it is within this probe's sensitivity, barring any equipment malfunction it should come up with a "correct" or "incorrect" answer. Obviously, if the answer is "incorrect" there's some work to be done. "Inconclusive" is typically used if there's an open-ended question where the eff
Re:Stephen Hawkings (Score:2)
Not to be a jerk here, but it cannot be "proven", it can only be shown to be incorrect. The reason why we call them theories is because we cannot be absolutely sure of why something happens. At the macroscopic level we of course can be very close and it doesn't matter very much, this is basic physics and the reason that newton's laws are still used even though they have been proven wrong.
Einstein has several theories/conjuctures that have proven to be wron
Re:So... (Score:5, Insightful)
I'm sure they thought that 75 years ago about Quantum Theory. This is a relatively big deal even if it isn't sexy. I mean, we have to test these things. How many chances do we get to observe major space-time dilation? I mean, minor stuff with satellites, right? But it's hard to get tests of theories involving planets.
Re:So... (Score:5, Insightful)
Proving things that are suspected to be true is the meat-and-bones of science. After all, they might turn out to not be true. Idle speculation may have been good enough for Aristotle the Things-Will-Stop-Moving-Without-the-Application-o
Re:So... (Score:2)
Re:So... (Score:2)
Re:So... (Score:2)
Well, the alternative is not to prove what we suspect to be true. Not a very smart idea, hmm?
Really, the Gravity Probe B mission has been delayed over and over again over the years, so it's a relief that we are finally getting some results. (Though analysis will still take time, probably...) If we get what GR predicts, then fine. We get to shut up a load of cra
Re:*woooooosh* (Score:4, Informative)
Oh, and don't try this experiment in Kansas. Relativity is only a theory, after all.
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Re:*woooooosh* (Score:5, Informative)
The idea of relativity is that no frame of reference is "special". Working this out for frames that differ by a constant velocity is pretty straightforward, but the situation with respect to rotation isn't so straightforward. If you spin yourself around you will quickly find that there does seem to be a special frame that doesn't make you dizy, which we call the non-rotating frame. To know that you are spinning, you don't appear to have to measure your rotation relative to anything else.
Einstein had the idea that really, rotation is relative, too, and this apparently special non-rotating frame is really just the frame in which you are not spinning relative to the other bodies in your region of space time. In other words, seen from a different region of the universe, maybe our region of the universe is spinning furiously, but we don't notice it because all the bodies near us are all spinning furiously together.
When you work out the math in the context of general relativity, the implication is that, near a big spinning body, for you to feel like you are not spinning you actually needs to be spinning slightly relative to what would fell like not spinning far away from the body. The effect is called frame-dragging [wikipedia.org]. This experiment tried to measure the frame-dragging effect of the Earth on some extremely precise gyroscopes in orbiting satelites.
Re:*woooooosh* (Score:2)
Consider a barbell: two masses linked by a bar with a strain gauge. If they're rotating around the COG through an axis different from the bar axis, the strain gauge will detect the 'centrifugal' force. Now float this object somewhere in space. Clearly, you will see if it's rotating by comparing its position to the stars. The strain gauge will tell you the same thing. Why ?
Does a universal inertial frame for rotation exist ? That would be strange, because that s
Re:*woooooosh* (Score:2, Informative)
This is precisely what general relativity says.
Re:*woooooosh* (Score:5, Informative)
The Gravity Probe B homepage has a far better introduction to the experiment. (Go to "classroom" -> "story of GPB" for a concise intro.)
http://einstein.stanford.edu/ [stanford.edu]
In short, general relativity predicts that a massive rotating object (like the earth) distorts the space around it in such a way that nearby objects that are locally at rest are actually rotating slightly when compared to distant stars. (Locally at rest means that, for example, if you put some guy in a box with any measurement apparatus he could imagine, his measurements would show that the box isn't rotating.) This doesn't happen in Newtonian physics, and Gravity Probe B should be able to measure it and compare it to what one predicts using GR.
The effect is usually called "frame dragging," or the "Lense-Thirring Effect."
Re:*woooooosh* Mod parent up (Score:2)
Re:Hmmm (Score:5, Funny)
The equation is 40DD=MC2.
Re:The earth is flat (Score:4, Interesting)
Re:The earth is flat (Score:2)
Re:Daaaaannnngggggggg (Score:2)
I suspect the really interesting advances will happen if it works in an entirely unexpected way.
Re:"Whatever!" (Score:2)
This "vortex" is a perfectly straightforward prediction of a now 100-year-old theory in physics (holding up quite well for all that), and is so freaking small it required an entirely dedicated, highly-sophisticated a fairly long time satellite to detect; it doesn't get much smaller than that.
Whatever MIS-TEER-IOUS [sluggy.com] thing it is you're thinking of, you're wrong.