31 replies to this topic

[fizzionz]

I have been thinking of ways to freeze organic matter without using cold and have come to the only conclusion that gravity must be used to obtain the goal of freezing organic matter without getting a crystalline structure formation. reasons why gravity can be the only universal force for such a process is its abilty to penetrate solid mater at equal strength at all distances. if strong gravatational forces were to pull a particle not only down but in all three spatial dimensions then the gravity could suspend an atomic structure. with a cell for example the cytoplasmic diffusion would stop and therfore cellular processes would be unable to function.

I just want my idea out there. maybe someone could tell me if this is a feasible idea. i think aliens could do it...

[forever freedom]

it's an interesting possibility.. i also want to hear some comments on that.


but currently we already have a technique that avoids the creation of ice crystals: Vitrification

[niner]

If a gravitational force were pulling equally in all three dimensions, it would add vectorially and you would get a diagonal force. But I guess you meant pulling from both the negative and positive directions in each dimension... but then you'd have no net force, so I'm not sure it would do anything at all. In fact, it would be unstable as any movement would cause the forces to unequalize and you would crash toward the closer gravity force. You would essentially have created a negative gravity well; more like a gravity hill. To do what you want, I think you'd want a well, so I guess you'd need an anti-gravity source at each of six positions... Even then, gravity is incredibly weak compared to chemical forces, so unless you applied ultra super mega anti-gravity, it wouldn't be a deep enough well to damp out thermal vibrations. Aliens could probably do it, but I think they might just use vitrification because it would be a lot cheaper.

[Mind]

Gravity is too weak a force to suspend motions of molecules, as niner explained.

[nefastor]

But I guess you meant pulling from both the negative and positive directions in each dimension... but then you'd have no net force, so I'm not sure it would do anything at all.

Actually it's like tug of war : it's not a matter of force, it's a matter of mechanical constraint. Gravity simply replaces rope. You can also think about the Lagrange points.

The intensity of the gravity would dictate how strong the physical "hold" on the target's particles is. Meaning, the immunity to systemic motion and shock. Obviously, the higher the better.

And even though gravity is a weak force, we know it can be cranked so high as to squash stars into black-holes, so at least in theory, gravity-based "stasis" should be possible.

I can see one or two technical challenges, though : suppose you need hundreds of G's to achieve acceptable stasis, and you can modulate gravity with 10% accuracy. That means you'll be pulling unequally along all three dimensions with differences of several dozen G's, largely enough to cause some serious damage. So, the more gravity you'll want to use, the finer your control over it is gonna have to be. Since the whole system would be automatic, that means improving the SNR of a feedback loop. There's a lot of math on the topic, so applying it to gravity might only pose problems in the actual implementation. The other problem would be the gravity sensors for the feedback loop : they'd have to be inside the device, where they'd be frozen. Not exactly sure how that might work, too.

Biggest problem : gravity decreases with distance, like magnetism. Put two gravity sources face to face and there's only going to be a single plane (Lagrange plane ?) where their forces match each other. Anything above and below that plane will be pulled in one direction UNLESS your gravity generators can be engineered to produce the same type of uniform field that a pair of Helmoltz coils produces. These coils basically shape magnetic flux lines : it remains to be seen whether or not something similar is doable with gravity.

Of course we still need to find a way to produce gravity. Let's get back to this thread once the Higgs boson has been tracked down by CERN

Good thinking, Fizzionz : I don't think anyone ever thought of that, including science-fiction writers.

Nefastor

[niner]

But I guess you meant pulling from both the negative and positive directions in each dimension... but then you'd have no net force, so I'm not sure it would do anything at all.

Actually it's like tug of war : it's not a matter of force, it's a matter of mechanical constraint. Gravity simply replaces rope. You can also think about the Lagrange points.

The intensity of the gravity would dictate how strong the physical "hold" on the target's particles is. Meaning, the immunity to systemic motion and shock. Obviously, the higher the better.

And even though gravity is a weak force, we know it can be cranked so high as to squash stars into black-holes, so at least in theory, gravity-based "stasis" should be possible.

I can see one or two technical challenges, though : suppose you need hundreds of G's to achieve acceptable stasis, and you can modulate gravity with 10% accuracy. That means you'll be pulling unequally along all three dimensions with differences of several dozen G's, largely enough to cause some serious damage. So, the more gravity you'll want to use, the finer your control over it is gonna have to be. Since the whole system would be automatic, that means improving the SNR of a feedback loop. There's a lot of math on the topic, so applying it to gravity might only pose problems in the actual implementation. The other problem would be the gravity sensors for the feedback loop : they'd have to be inside the device, where they'd be frozen. Not exactly sure how that might work, too.

Biggest problem : gravity decreases with distance, like magnetism. Put two gravity sources face to face and there's only going to be a single plane (Lagrange plane ?) where their forces match each other. Anything above and below that plane will be pulled in one direction UNLESS your gravity generators can be engineered to produce the same type of uniform field that a pair of Helmoltz coils produces. These coils basically shape magnetic flux lines : it remains to be seen whether or not something similar is doable with gravity.

Of course we still need to find a way to produce gravity. Let's get back to this thread once the Higgs boson has been tracked down by CERN

Good thinking, Fizzionz : I don't think anyone ever thought of that, including science-fiction writers.

Nefastor

You know, Nefastor, I'm not sure that gravity-based stasis is even possible. For one thing, it wouldn't be hundreds of G's you'd need, more like hundreds of thousands. But that's not the problem. The problem is achieving the field uniformity that you would need. The magnetic field within a Helmholtz coil isn't perfectly uniform; it varies by a few percent. With variations of that order given the magnitude of thermal energies, I doubt that you'd be able to maintain the structural integrity of a living organism. Of course, this assumes that a uniform gravity field could even be produced, which may or may not be possible. I guess I can't truly rule it in or out on theoretical grounds, although a serious physicist might be able to. I would just have to call it a practical impossibility. But certainly we could not do it with point gravity sources, as the organism would either be pulled apart or crushed, depending on whether gravity or antigravity was used.

[Reno]

I have an idea I'm going to pull directly out of my arse. How bout if we use the force of time to slow down the pull of particles in every conceivable direction. By stopping time we can hold the decay rate of trillians of independent cells indefinitely. What do you guys think, is this idea plausible? I think aliens could do it.

Edited by bobscrachy, 12 April 2008 - 07:19 AM.

[lunarsolarpower]

This topic reminded me of an idea I had a long time ago after reading a certain Douglas Adams quote:

There are some oddities in the perspective with which we see the world. The fact that we live at the bottom of a deep gravity well, on the surface of a gas covered planet going around a nuclear fireball 90 million miles away and think this to be normal is obviously some indication of how skewed our perspective tends to be

What if a future civilization with control of awesome unknown forces decided they were tired of existing as sitting ducks in a universal maelstrom that bombards you with gamma rays one minute, supernova emitted neutrons the next, then finishes it all off with the flyby of a thirsty black hole or some elusive dark matter? What better way to ward all these hazards off than a very tall mountain made entirely of gravity with a gentle pool at the top?

I made a quick sketch to illustrate the idea:



NASA has some fancier 3D pictures of conventional gravity wells.

[jaydfox]

I think I'm missing the point of how you intend to use gravity to create a stasis. If the gravity pulls from all directions at once, it just cancels out. For example, picture a hollowed out chamber at the center of the earth. There is mass all around you, tugging at you from all directions. You be weightless, however, with only the minutest levels of microgravity detectable as you moved away from the center of the chamber, and even then, that would mostly be due to the fact that the earth is not a uniform sphere, nor is it uniformly dense.

We could scale this up, of course. A hollow chamber at the center of the sun would also provide a for a great degree of gravitational forces pulling on you from all directions, but again, you would be pretty much weightless, with no net forces.

Time would run a little slower in such a gravity well, but this is not so much because of stasis as because of general relativity. At any rate, all molecular/chemical properties would be affected, such that cellular processes would not appear to be slower to someone in the chamber. Only for an observer outside the chamber would any difference be notices, and for a small mass like our sun, the difference would be pretty small anyway (I venture to say less than 0.1%)

Not unless you plan to build a chamber in the center of neutron star would you have any luck. And again, that's not stasis, just an application of general relativity and time dilation.

Unless, of course, you remove the requirement for no net forces. If you put a human body under 100 g's of constant acceleration, you would pretty much crush it into pulp. The density of bone and muscle is more than that of water or fat, so the body would try to separate, like cream rising to the surface of milk.

At thousands of g's or more, the problem just gets worse.

You could maybe successfully preserve a brain at 100 g's, since it's fairly uniform in composition. But I don't think 100 g's is going to do much in the way of "stasis". The increased strain on cellular membranes will probably burst all the neurons in the long run anyway...

[vyntager]

What if a future civilization with control of awesome unknown forces decided they were tired of existing as sitting ducks in a universal maelstrom that bombards you with gamma rays one minute, supernova emitted neutrons the next, then finishes it all off with the flyby of a thirsty black hole or some elusive dark matter? What better way to ward all these hazards off than a very tall mountain made entirely of gravity with a gentle pool at the top?

Like surrouding yourself with the antigravitational equivalent of a black hole gravitational field, event hrizon, or at the very least a neutron star's ?

The difference being that, for a black hole, even at c you can't get out, here, even at c you couldn't get in ?

There's a similar idea in Alastair's fiction, the Shrouders (but it's not exactly an antigravity peak that's being used there)

The Bubble in Egan's quarantine works a bit like that too, though it appears to works both ways (can't get in, can't get out)

If the gravity pulls from all directions at once, it just cancels out. For example, picture a hollowed out chamber at the center of the earth. There is mass all around you, tugging at you from all directions. You be weightless, however, with only the minutest levels of microgravity detectable as you moved away from the center of the chamber, and even then, that would mostly be due to the fact that the earth is not a uniform sphere, nor is it uniformly dense.

Made me think about laser cooling, though I don't think the same thing could be achieved with gravitational waves (let alone doing it for every single molecule or atom in a body).

[nefastor]

You make valid points, Niner, but in the end all the potential issues you listed can be solved through improved engineering. For instance, the uniformity of the magnetic field between Helmoltz coils is dependent (among other things) on the coils being perfectly identical and perfectly aligned. It's obvious we know more today about making coils accurately and precisely positioning them than we did when we first invented the electromagnet.

I figure once artificial gravity gets out of the scientists hands and into those of engineers, the devices will be gradually improved. Same way we improved lasers and optics to go from the CD to the DVD to the BlueRay disc (steps which required mostly manufacturing improvements to a technology that essentially remains the same).

Bobscrachy, I did think of slowing time using extreme gravity to achieve stasis. But I'm not sure if it would work that way : as I understand it, the kind of time-slowing effect we see in movies involving (say) black holes is not due to the gravity of the black-hole itself, but to the fact that objects around black-holes inherently have very fast orbits. So time slows down not because you're experiencing a lot of gravity, but because you're travelling at utrarelativisitic speeds (above 30% of the speed of light)

You COULD reproduce the effect without a black-hole, though : in the Forever War, Joe Haldeman describes people flying their ship in circle, at ultrarelativistic speed, so they could live long enough to wait for the return of loved ones (which could take centuries). In this scenario, you'd use artificial gravity for propulsion, so that you could accelerate to the right speed quickly enough.

Needless to say, there's a lot of problems with this concept, such as finding a circuit in space where you'd be reasonnably sure you're not gonna hit debris : at these speeds they'd be unavoidable AND deadly.

Lunarsolarpower : Wow now that would be awesome. I'm trying to picture in my mind the kind of device(s) and infrastructure you'd need to create your fortress. I think we're looking (at the very least) at a spherical array of gravity generators in orbit, the failure of any single one of them leading to the Earth getting blown to bits. You know, so far Earth has known a lot less catastrophic failures than what man alone has triggered

If anything we engineer could be 100% safe, though, I think this would be great. But we could just as well use our knowledge of gravity to deflect anything that comes our way, perhaps towards the Sun. Your idea is nice because, of course, we wouldn't need to aim at anything. But you'd still have to be able to make exceptions of, say, space ships, so it's not really less complicated.

I think I'll rather go with land-based anti-celestial-body doomsday weapon. Turn the Earth into a Death Star.

Jaydfox : read about Lagrange points. It's really like a tug of war, gravity doesn't exactly work like magnetism. Say you have two identical cars and link their rear fenders with a chain, then have them move in opposite directions : the cars won't go anywhere, neither will the chain. In what we're discussing here, the chain would be your body's atoms, the cars would be gravity sources.

Nefastor

[Cyberbrain]

As others have pointed out, gravity may not be the best solution to slow down the rate of decay of dead body. But if you were to speed up that body near the speed of light, then it would slow down enough for us to find a way to revive it.

[nefastor]

As others have pointed out, gravity may not be the best solution to slow down the rate of decay of dead body. But if you were to speed up that body near the speed of light, then it would slow down enough for us to find a way to revive it.

Well, to be fair we're not looking for an optimal solution, here, we just toying with a concept and how we could implement it. We're making so many assumption we pretty much have a 100% margin of error

Nefastor

[eternaltraveler]

What Jay said.

Gravity would not "pull" in two or more directions like a tug of war. It would cancel out and you would be left weightless. Even if you could somehow sit in between 2 super massive black holes with billions of gs being emitted from each of them the result would be no different then astronauts in free fall (orbit).

[jaydfox]

What Jay said.

Gravity would not "pull" in two or more directions like a tug of war. It would cancel out and you would be left weightless. Even if you could somehow sit in between 2 super massive black holes with billions of gs being emitted from each of them the result would be no different then astronauts in free fall (orbit).

Actually, it'd be worse. If you could sit between two very dense objects (like neutrons stars orbiting each other, to be semi-"practical", or black holes somehow held apart), the gravity would cancel out, such that you didn't fall towards either. However, the gravitational field would not be the same as weightlessness. Move slightly away from the dead center of the system, and you'll experience a net force. This is a so-called tidal force, which increases as you move away from the center of the system. It manifests itself as a stretching along the axis between the two masses, and a squishing along the other two axes. The typical description is that an object in this position would be stretched like taffy (which, as it stretches, gets thinner).

By the way, these tidal forces would exist a Lagrange points as well. In either case, if the fields are strong enough, they'd rip a human body apart.

[nefastor]

What Jay said.

Gravity would not "pull" in two or more directions like a tug of war. It would cancel out and you would be left weightless.

Seriously, read about how Lagrange points work. There is a big difference between "forces canceling each other" and "no force at all". It's totally counterintuitive, but hey, there's a reason why most people don't "get" relativity : that sort of stuff is hard for our brains to visualize.

By the way, these tidal forces would exist a Lagrange points as well. In either case, if the fields are strong enough, they'd rip a human body apart.

Very true, which is why we postulated uniform gravity field, so there would be no stress of the liaisons between atoms. You could crank gravity as high as you'd want without having to worry about tidal forces.

Nefastor

[eternaltraveler]

This is a so-called tidal force, which increases as you move away from the center of the system. It manifests itself as a stretching along the axis between the two masses, and a squishing along the other two axes. The typical description is that an object in this position would be stretched like taffy (which, as it stretches, gets thinner).

this would be the case between two stellar mass black holes (or just falling into one stellar mass black hole), but would not be the case in such a situation between two super massive black holes. Well it would, the tidal force you are describing would just be infinitesimal.

[eternaltraveler]

This is a so-called tidal force, which increases as you move away from the center of the system. It manifests itself as a stretching along the axis between the two masses, and a squishing along the other two axes. The typical description is that an object in this position would be stretched like taffy (which, as it stretches, gets thinner).

this would be the case between two stellar mass black holes (or just falling into one stellar mass black hole), but would not be the case in such a situation between two super massive black holes. Well it would, the tidal force you are describing would just be infinitesimal.

at least above the event horizon that is.

[jaydfox]

What Jay said.

Gravity would not "pull" in two or more directions like a tug of war. It would cancel out and you would be left weightless.

Seriously, read about how Lagrange points work. There is a big difference between "forces canceling each other" and "no force at all". It's totally counterintuitive, but hey, there's a reason why most people don't "get" relativity : that sort of stuff is hard for our brains to visualize.

It's not that I don't understand Lagrange points, I just don't see what it buys you. Within a given block of relatively empty space (e.g., for all intents and purposes, the space occupied by a human body is empty, having a density dozens of orders of magnitude smaller than that of a neutron star), gravitational tidal forces cancel each other out, such that any gravitational stretch along 1 or 2 axes is balanced by a squeeze along the remaining 2 or 1 axes respectively. If we eliminate tidal forces altogether, then there is no net force. In which case, what is the gravity actually doing to provide "stasis"?

In the absense of general relativistic considerations, NOTHING! If we assume negligible tidal forces, then all you get is free-fall. In which case, the gravity is doing nothing that isn't already being done in the absense of the canceled gravitational fields in the first place. Same story whether we're balanced between two masses or sitting at a Lagrange point. If we use the gravity to actually apply force, such as on the surface of a planet, then you're not doing anything you couldn't already do with good old fashioned acceleration, and at any rate the force is applied by means of pressure from the accelerating surface (i.e., the "ground"). Pressure can also be had in a pressure tank, and with much greater uniformity to boot (i.e., the pressure would be from all directions, eliminating the risk of separation of materials of varying densities). But, for example, I'm not sure storing a body at the bottom of the ocean buys you much, except perhaps because if it's nearly zero Celcius at depths in the range of 10 km.

When we do consider general relativity, then we get time dilation. But this isn't stasis in the sense of the atoms being "held in place". It's just good old fashioned relativistic time dilation. You can accomplish the same thing by traveling around in a spaceship at near lightspeed, and the latter is arguably far easier technologically, making the whole consideration of gravity kind of silly.

I'm really not seeing how gravity is being used to provide anything other than relativistic effects, which are not remotely comparable to cryonics in terms of molecular stasis.

[Luna]

How about time dialation field?

[jaydfox]

How about time dialation field?

Hmm, depends on what you mean by that.

Using either intense gravity or high velocity to achieve significant time dilation is impractical for achieving "stasis", for one major reason: the time required to reach the desired time dilation effect. For simplicity, consider how long it would take to reach a speed of half the speed of light. Even at a brutal 15 g's of acceleration, it would take weeks! No good for preserving a dead body, as only days or even hours are necessary to cause irreversible damage (information loss).

As for gravity, consider how long it would take to "fall" to the desired height above a supermassive black hole. Again, depending on the exact scenario, probably days if not weeks. The larger the black hole, the longer it would take, so you'd actually want as small a black hole as possible without encountering fatal tidal forces. Perhaps your best bet is to accelerate at, say, 10-20 g's towards a medium-sized blackhole (tens of thousands of solar masses), taking advantage of both forms of time dilation and decreasing the time necessary to get to close to the black hole. Of course, for this to be of use to a dying person, they'd have to be close to the black hole to begin with. Starting light-years away does you no good!

Another alternative would be to use gravity to accelerate you towards the black hole without you having to withstand the acceleration. For example, if you were to fall in the wake of a very large, dense planet, which had a surface gravity of 100 g's, but which was itself accelerated at 99 g's towards the black hole, such that your body felt a gentle 1 g of acceleration. The would get you to the black hole much faster. Or, you could accelerate up to near light-speed much faster, by accelerating at 99 g's along with the planet, but only feeling 1 g of acceleration.

I suppose other tricky scenarios could be created, where the body could quickly be driven down into a deep gravity well, or accelerated up to a high speed, without local gravitationl forces crushing the body into so much goo. But at the end of the day, I'm still not seeing the point. Seems like an awful lot of energy to expend for such a marginal effect.

[Luna]

My thought was actually to have a gravity device that will create a statis time dialation field inside the pod in order to preserve the person.

[nefastor]

It's not that I don't understand Lagrange points, I just don't see what it buys you.

I've whipped out the good-ol' pen and paper and I know what's wrong with our stasis machine. You're right, Jaydfox, a Lagrange point does not provide the type of constraint we need. The only way this could work is if we somehow modulated gravity along all three dimensions, and very locally, to counter the movements of individual atoms in the target, in real time.

That's a complicated solution, but it's probably doable if you add a really advanced FMRI device to the stasis machine. And a really badass supercomputer to track each atom. I'd rate that solution as equivalent to Star Trek's "transporter" in terms of processing power requirements. Moore Law's helping, we should get there next year

I feel there's something here, though... I'll keep toying with the concept in my head. If I find something I'll share with you guys.

Of course you realize this could be the ultimate weapon : if you could freeze your enemy in time, he's pretty much screwed. He could be as badass as Mecha-Godzilla, as long as he's made of atoms, he's screwed anyway. Kinda scary if you think about it.

My thought was actually to have a gravity device that will create a statis time dialation field inside the pod in order to preserve the person.

Upon checking, gravity doesn't impact the rate at which time flows. Only speed (gravity is a force, meaning it's acceleration).

If you control gravity, however, you could make a device here on Earth that uses the effect of speed. If would be a centrifuge like NASA uses to train astronauts, but accelerated in a vaccum and without moving parts (kinda like a brushess DC motor). That way it could rotate its nacelle to relativistic speeds. And you could generate gravity radially to counteract the centrifugal force for the passenger.

It would be a big machine, but not too big, and it would have two awesome advantages over a spaceship build for the same purpose :

- You can ensure there won't be killer debris or asteroids inside a centrifuge, it's a man-made enclosed space.

- The absence of engines and on-board power supply means the nacelle would be very light and so could accelerate much faster and cheaply.

Problem is, in space, your engine fails, you keep going straight forward until you hit the next celestial body (several years later, probably). In the centrifuge, power goes out, the first thing you notice is you're hitting the wall with the force of a million atomic bombs. And that's gonna leave a mark

Nefastor

[eternaltraveler]

Upon checking, gravity doesn't impact the rate at which time flows. Only speed (gravity is a force, meaning it's acceleration).

yes it does, and further this effect has been confirmed experimentally

see

http://en.wikipedia....l_time_dilation

[nefastor]

Upon checking, gravity doesn't impact the rate at which time flows. Only speed (gravity is a force, meaning it's acceleration).

yes it does, and further this effect has been confirmed experimentally

see

http://en.wikipedia....l_time_dilation

Taken from that page :

Important things to stress :

* According to General Relativity, gravitational time dilation is copresent with the existence of an accelerated reference frame.

With currently available technology, we can't gravity-induced measure time dilation in a static setting : there will always be motion. In fact, mass and motion are quite entangled in Einstein's theories (it's not just in e=m.c²) : an object's mass increases with speed, therefore so does its gravity potential, so what actually causes the time dilation ? The increased gravity from the increased mass, or the speed which increases the mass in the first place ?

The "Experimental confirmation" section of the page you linked pretty much illustrates this : all the tools we have involve motion : data transmission, planes and satellites.

This is not to say there's no way you can achieve time dilation in a static setting, but at this point we have no way to test that. Perhaps that's one of the things the LHC will help us with, if it leads to the discovery of artificial gravity.

Assuming you could slow time through the mere presence of gravity, with no motion involved, then there's a chance the stasis machine we're discussing could work in the form it was proposed initially, or in a machine of similar complexity. That would definitely be an outcome science-fiction hasn't predicted yet.

Nefastor

[eternaltraveler]

With currently available technology, we can't gravity-induced measure time dilation in a static setting : there will always be motion. In fact, mass and motion are quite entangled in Einstein's theories (it's not just in e=m.c²) : an object's mass increases with speed, therefore so does its gravity potential, so what actually causes the time dilation ? The increased gravity from the increased mass, or the speed which increases the mass in the first place ?

umm what? We can indeed induce gravitational time dilation in a static setting (or rather, we don't need to, as it's already happening). You are experiencing time slower now than you would be away from the earth and other large masses.

You're misunderstanding. Time dilation at relativistic velocity is not because it's apparent mass increases. A small particle accelerated to relativistic velocity does indeed increase in apparent mass, but this does almost nothing to it's time dilation. If we accelerate it in a particle accelerator here on earth and even if it's mass is increased many fold it is still in the vicinity of a much larger mass, the earth.

Clocks run slower on earth than they do away from the earth. Similarly they would run much slower in the vicinity of an even larger mass. this can be (and has been) measured when these clocks are completely (or reasonably) stationary relative to each other.

Edited by elrond, 16 April 2008 - 08:28 PM.

[nefastor]

Sorry Elrond, I know this is quite hard to picture, but we have never experimented with gravity-induced time dilation in a static setting because there's no such thing as a static setting where natural gravity is involved.

The experiment you're referring to wasn't meant to prove time goes slower at the bottom or Earth's gravity well. It was meant to prove time goes slower in a fast-moving object like a satellite.

It's gravitation 101 : when an object is subject to the gravity of, say, a planet, only two things can happen : either the object moves fast enough around the planet that its centrifugal force matches the force of gravity (it's in orbit) or the object has insufficient velocity (or none at all) in which case it will fall straight down until it lands. In both cases you have motion, and therefore speed. Also, you don't need to hit relativistic speeds to get a measurable time-dilation. It was first observed on an airplane (and not even a supersonic one).

Now, suppose you have a machine on the ground that can generate 1000 G or artificial gravity and you put an object inside : Earth, the machine and the object inside all move at the same speed through space. I don't think anybody knows what's going to happen, but it's a safe bet time will slow the same way for the object as it does for the rest of us.

To prove gravity has a time-dilating effect, we'd need to place atomic clocks at the top and base of a tall tower, and see if they diverge. Does anyone know if this has been done before ?

Nefastor

[eternaltraveler]

Oh good grief.

I have stated that these experiments have been done. These clocks they put on airplanes were fast. Therefore the time difference they experienced is primarily due to the difference in gravity, not their relative velocity to us (if it was due to the relative velocity they would be slow). This is also true of GPS satellites which move much faster. The effects of special relativity would be expected to make them slow by about 7 microseconds per day due to their relative velocity, but the fact that they are in a micro gravity environment would be expected to make them fast by about 45 microseconds per day. Or in total be fast by 38 microseconds per day (45-7).

If the GPS satellite did not use both special and general relativity concepts (both velocity & mass induced time dilation) they would not work. They do work and they have the equations for special and general relativity wired into them. Ipso facto. Experiment done. (we have many many other independent confirmations of mass induced time dilation). Just do a simple search in google and you'll find all the references you want.

other than trying to be right, I don't understand what you are arguing.

Edited by elrond, 17 April 2008 - 09:43 PM.

[nefastor]

D'oh ! Upon checking, my memory did fail me. Blame it on what you will, but I was wrong on this one. It's either dyslexia or some sort of crazy prejudice (I'd prefer crazy prejudice) but I totally thought the atomic clocks in the planes went slower as they moved faster than the control clock. Sorry for the waste of time. Mea magna culpa.

So, what does this mean for gravity-induced stasis ?

Nefastor

[bgwowk]

Here's some Relativity trivia. If you observe an object being swung around in a centrifuge, you can use Special Relativity to calculate how much time will slow down because of the speed it is moving at. On the other hand, you can also view the object as being at the bottom of a gravity well because of the acceleration forces that keep it moving in a circle. If you use the General Relativity formula for time dilation in this gavity well, you get the same answer that Special Relativity predicts based on motion alone. It's different ways of looking at the same thing, something that happens often in physics.