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Is the Earth in a Vortex of Space-Time?
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."
I think it's interesting - general relativity makes some very hard to verify but specific predictions. Many competing theories to it over the last 50 years have made predicitions that have, one by one, turned out to be false. Rotational frame dragging is (I think?) one of the last unverified ones. According to Newtonian gravitation & mechanics, the rotation or non-rotation of the earth should not affect an orbiting satellite a whit (ignoring "complications" like variable atmospheric drag based on rotation rate, different shape of earth at different rotation rates, etc.), or put more abstractly, the rotation of an axially symmetric mass distribution should not have anything to do with its gravitational field. General relatitivity does not agree with Newtonian mechanics here, which brings up yet another interesting question:
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!
Parent's link is nice and making fun of the average impression people hold on "no time" (at least that's why I get a laugh out of it) as it doesn't make sense to think of "no time" as hitting pause on your remote control. It seems much more likely (almost a logical certainty?) that "no time" is like hitting a button on your remote control and suddenly you see the whole dvd/whatever in an instant, and in the next instant (not that it would be easy to differentiate between it) you see the whole dvd/whatever as well, and in the next instant, and the next and so on forever (forever is all that exists outside time).
s /universe.html
:)
Welcome to how god sees the complete existence of the universe or would see it if such an entity (god) exists. Realize that such a point of view removes the inherent contradiction between free will and fate. Also savour the following implication of "no time" or "outside time": unlimited bandwidth/information communication. That has implications making it possible for such an entity to be absolutely moral as it has absolute knowledge of everything that has ever happened, all causations and effects: if one didn't have such complete knowledge one couldn't make any kind of justifiably correct decisions; which in itself has further implications for everybody that are aware that their knowledge is less than absolute - humility.
Could it be that a phenomena such as spooky action at a distance through entanglement is our first observed clue into practical use of this "part" of existence?
Take all this and combine it with the speculative view of massless particles, i.e. a pure waves whose medium is space/time itself, as the informationrich, faster than speed, "dataway" of souls and you'll get both a bunch of kooks and people who realise that monotheistic religions might have been basically right all along... (some of you might not differ between the two, I know I know lol).
Offtopic but I'll throw it in anyway:
http://www.veritas-ucsb.org/library/origins/quote
For any and all atheists reading this don't worry, be happy
this comment is provided "as is" and without any express or implied legibility or congruity [...]
Seriously, though. What the hell does "stationary" mean in space?
Nothing, that's what. If anything's stationary. it's the observer. So yes, Earth is as stationary as a planet can be, and the universe revolves in a really complicated way around us.
Yeah, the earth is somewhat flattened (actually, pear shaped due to Antarctica holding more glaciers than the arctic.) The amount of deformation is so small that the human eye perceives it as perfectly spherical. The Earth is rounder and smoother than a pool ball, for reference.
I'll never make that mistake again, reading the experts' opinions. - Feynman
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...
Real Daleks don't climb stairs - they level the building.
If it sounds like a scifi novel, that's no the fault of the science. It's merely the fault of book writers co-opting science terms and/or sci-babble to sell more books.
The science remains the same.
Anyway, this is important research. We are kind of like a baby learning that he can move his foot and touch something (doesn't know what yet, but something is there) or touch his blanket with his fingers. We are just learning to touch gravity even though we all live within it every day. We have to start by poking at it.
Eventually we will work out that gravity is merely a manifestation of space-time, and later on figure out that space-time and gravity can be controlled. Control space-time and you've just unlocked the universe. That's like the baby finding the lock on the craddle and tumbling to the floor of a great big room.
No, "Our planet spins, and the spin should twist the dimple, slightly" explains leap years, daylight savings time, Leap year exists because the earth takes 365.2422 days to orbit around the sun. This is number is ridiculously too complicated to use so a system was created in which a day is added every four years to make up for the lost .2422 days.
In the Gregorian calendar, which is the calendar used by most modern countries (the USA), the following rules decides which years are leap years:
1. Every year divisible by 4 is a leap year.
2. But every year divisible by 100 is NOT a leap year
3. Unless the year is also divisible by 400, then it is still a leap year.
These rules account for the calendar to never be to far out of whack. Interestingly the year 2000 (which was a leap year) is the first time the third rule has been used since the creation of this system.
Daylight saving time was thought up by Ben Franklin in 1784, to make the most of our daylight. This allows the time to fit the sun. The idea of time zones and day light savings time is to have the middle of the day occur at noon. Studies have show that daylight savings time saving electricity due to less lights in the evenings.
The official spelling is Daylight Saving Time, not Daylight SavingS Time.
Saving is used here as a verbal adjective (a participle). It modifies time and tells us more about its nature; namely, that it is characterized by the activity of saving daylight. It is a saving daylight kind of time. Similar examples would be dog walking time or book reading time. Since saving is a verb describing a single type of activity, the form is singular.
Nevertheless, many people feel the word savings (with an 's') flows more mellifluously off the tongue. Daylight Savings Time is also in common usage, and can be found in dictionaries.
Adding to the confusion is that the phrase Daylight Saving Time is inaccurate, since no daylight is actually saved. Daylight Shifting Time would be better, but it is not as politically desirable.
So, neither day light saving time nor leap years are explained by this time space distortion caused by earth's gravitational effect and explained by Einstein. Although Einstein supported day light saving time. They are policies thought up by humans to fix / modify a system thought up by humans and not based on any physical properties.
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Then again, I thought the other test results a few years ago demonstrating gravity was bound by the speed of light suggested its particulate exchange nature, and thus it was not a fundamental feature of spacetime geometry.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
My first thought on this was "Whatever! Another crackpot theory about how the universe has special mystical things happening." But then I stopped and thought "Oh yeah, we thought the earth was flat, once." My prediction, in the end, is that this will mean nearly nothing in our generation when all is said and done. Just like the earth being round meant nearly nothing back then, the freaky time vortex we live in will have very very little to do with the common man today. Once we invent some magical mystical space transportation, yeah, it'll probably matter, but not until then.
"If you make people think they're thinking, they'll love you; But if you really make them think, they'll hate you." - DM
Einstein would probably have been surprised at this particular application of relativity.
It's all relative and while this experiment may prove/disprove certain ascertions, it does nothing to answer the question of what happens to the speed of light when:
Vehicle A traveling in car at 80mph with it's headlights illuminated toward a double slit apparatus and one side has been saturated in a Bose-Einsteinian Condensate.
Things that make you go hmmmmmmmmmmmm
If car A travels speed A and the headlights are on does that mean that the light from the headlamps exceed the speed the light respective to the speed of the vehicle?
Remember the speed of sound was also a constant at one time. Can you imagine the change in physics and if c is not a constant?
-drunk anonymous coward
Could someone please explain to me how this works? You are in a cylinder (spaceship or whatever) in space, you start rotating the cylinder and somehow the astronaut inside gets sucked to the wall. Where is the centrifugal force coming from?
I really dont think it would happen. I think that people are using the earth based ideas of the gravitron (the ride that spins around and you get sucked to the wall). But there is one important force in space, the earths gravity. Correct me if I am wrong but the gravitron gets it ability because you are also being affected by the earths gravity, which would not apply in space. I dont know if I am missing something but I've debated this with my physics PHD friend and he really couldnt put up a good arguement for the spinning gravity arguement.
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 any more validation of GR than we already have. If they really want to validate frame dragging, they need to look for weirdness associated with very large spinning objects, like black holes. If you could study black holes enough to find some behavior along the axis that contradicts classical physics, that would give you some meat to back the concept of frame dragging.
It's not even so much relativity at all; these principles were understood before 1900. If you're in a spinning reference frame, things work differently. Spinning your reference frame is not the same as moving it at a constant velocity -- while you can't tell how fast you are moving in the absolute sense, you can tell precisely how fast you are spinning. 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.
;P), and we'll all have migraines when the little shit is done...
Apparently, he does have to say more, since in "Relativity: The Special and General Theory" Einstein discusses the nature of rotating frames of reference, and then goes on to elaborate on the nature of General Relativity for another six chapters and discusses Gaussian co-ordinate systems. General Relativity is slightly more complex than talking about spinning reference frames.
How can you find a toddler falling over funny? Now he's gonna scream his little head off for a half-hour (Given that the toddler and us are both in Galilean reference frame K
Nope. Let's say we have two people in a ship going .99c, one in front and one in back. The guy in the back shoots a red laser towards the front. Here's what an external observer would see:
.99c would see if you and a friend shot red lasers down the hall at each other.
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 moving away from their source, so they get red-shifted back down to red. As long as the two aren't moving relative to each other, any red/blue shift will cancel each other out. The opposite happens if the front guy shoots a laser towards the guy in the back.
Note that this is also *exactly* what an observer flying past your house at
Would you like to know more?
Of incandescent gas
A gigantic nuclear furnace
where hydrogen is built into helium
At temperatures of millions of degrees
The sun is hot
We need its lightThe sun is not
A place where we could live
But here on Earth there'd be no life
Without the light it gives
we need its heat
We need its energy
Without the sun, without a doubt
There'd be no you and me
Note: Because the photon is traveling at the speed of light, and because time compresses the closer you get to the speed of light, when your AT the speed of light, like a photon, there IS NO TIME between when your sent out and when you end.
Thus, for the photon, it excisted for exactly 0 seconds, and thus, again from it's point of view, nothing happend to it because things happening is always definied over an interval of time.
Quick answer: It doesn't 'see' any change because it doesn't see, there's no time too.