Time Travel

Pseudoscience and the Paranormal
41

Since this is pseudoscience and not “real” science, I suppose I can take a stab at the notion of gravity warping space on the evidence of light bending. It seems to me that in order to accept a warp we would have to believe that light is propagating through a medium. This means we would have to accept that space is the medium. We would have to believe that space has a structure which can be compressed by gravity. This would mean that space is composed of something. If space is compressed by gravity it would have a variable density. A variable density in space would mean the speed of light is variable.

I expect the Sun’s atmosphere, a huge thing if we include the heliosphere, could be the cause of at least some of the bending (lensing) of light.

All I know about atomic clocks is that they use the frequency of emissions from electrons to keep time. In orbit, such a clock would be constantly accelerating. Gravity (and acceleration) can change the frequency of light. I’ve read about experiments measuring this in deep holes (mines I think) and also comparing differences in frequencies at the base of a mountain compared to those at the mountain top. Just getting the clock into orbit (and back down again) would expose it to even more acceleration. I don’t know how much acceleration figures in to the observations and calcs. It must be a factor.

I do not accept that speed alone in empty space will change the clock’s frequency. If this actually happens, there must be another explanation. It may be that the internals of the clock are interacting with the medium of space.

42
Bob said,

This means we would have to accept that space is the medium. We would have to believe that space has a structure which can be compressed by gravity. This would mean that space is composed of something. If space is compressed by gravity it would have a variable density. A variable density in space would mean the speed of light is variable.


Actually the opposite is true. The speed of light is invariable (constant “c”). It is space and time which are not absolute.

Einstein’s “man in a box”

Imagine you are floating in a box, unable to see what's happening outside of the box. Suddenly, you drop to the floor. So what happened? Are you being pulled down by gravity? Or is the box being accelerated upward by a rope yanking it upward?

The fact that these two effects would produce the same results led Einstein to the conclusion that there is no difference between gravity and acceleration — they are the same thing.

Now consider Einstein’s previous assertion that time and space are not absolute. If motion can affect time and space, and gravity and acceleration are the same thing, that means gravity can actually affect time and space.

The ability of gravity to warp spacetime is a huge part of Einstein’s general theory of relativity.


If you were to shine a light through a pin hole in the accelerating box, to the man inside the box it would appear to bend, but it would reach the other side of the box at the same time as if the box were standing still and the light was following a straight path.

Think about that remarkable counter-intuitive fact. Mind boggling.

43
I do not accept that speed alone in empty space will change the clock’s frequency. If this actually happens, there must be another explanation. It may be that the internals of the clock are interacting with the medium of space.
This has been proven to be true. An atomic clock works on the decay of radioactive material. While a single radioactive atom may decay unpredictably at any time, a group of radioactive atoms together, of the same radioactive element, decay at a precise rate. This is called the "half life" of the material. No matter how much material there is in this lump, half of it will decay in the material's half life. Wait that amount of time again and half of what's left will decay. Since half the material will decay in a given amount of time, by knowing how much material there is to begin with you can make very accurate predictions about when a particle is going to be released. It's off by seconds in tens of thousands of years.

The speed at which an atomic clock travels affects the decay rate of the atomic material, slowing down the clock. (Oh, and acceleration is accounted for in GPS satellites. Their clocks have to be extremely well synced, so they are constantly adjusted to match.) This has been absolutely shown to be true in every way we could imagine to test. Put it on a plane, go with the rotation of the earth, the clock slows down. Put it in a plane, go against the rotation of the earth (meaning you’re actually decreasing your speed), the clock speeds up. That this happens is absolutely certain, observed as expected in every single test. This is relativity, the warping of time by speed of travel.

And you mentioned something about the sun’s atmosphere bending light. There are tests for warped space too, but we generally look a little further away. Look up “gravitational lensing”. It produces a lot of interesting phenomena. A star hidden behind a planet will show up as 4 stars at 4 different points around the planet when in perfect position. And if we want to look really, really deep into space we look for 4 stars near each other with a nice gap between them because that makes a cosmic magnifying glass which we can peer through. The space between the 4 stars is warped in such a way that it causes magnification, a gravitational lens, in between them. This is spatial warping.

All of this was theorized by Einstein and proved by testing and observation. That these things happen is fact. You may be able to come up with an alternate explanation for why, but speed through empty space alone does, in fact, cause time to move at a different rate.

44

Write4U: “Actually the opposite is true. The speed of light is invariable (constant “c”). It is space and time which are not absolute.”

You forgot to include the second sentence in my post. What that part of my post meant is that in warped space the speed of light would not be constant. Something you point out, correctly, that we do not accept.

Let me say it this way: We accept that light moves through a volume of space at a constant speed. That volume along the vector of the light’s speed and direction will constitute a distance “d-1” equal to C times the time “t” the light moves. Let us say that the space is compressed (warped) to twice the density of the space when uncompressed. The distance “d-2” that the light will travel at C in time “t” in the compressed space will now be one-half “d-1”. Why? Because the distance would be compressed too and there would be twice as much space in the compressed volume and it would take the light twice as long to move through the compressed volume. We would observe the light moving at one-half C while it is in the compressed volume. Since we cannot accept this, what can we conclude? For us to observe the speed of the light as constant inside the compressed volume we would need the light to speed up to twice C. Do we want to accept that? Probably not. In order for us to observe a constant C while the speed of the light actually would be C we cannot accept that the volume was compressed.

This is why I don’t accept the notion that space is actually warped by gravity. I think it much better to say that the effect of gravity acting between objects in space makes it appear as if space is warped by gravity. I suggest that “appear as if” is not the same as “is”.

45

Write4U: “Think about that remarkable counter-intuitive fact.”

It would not matter if the source of the light were inside or outside. The light does not bend. Each light wave follows a straight path away from the source. It is only the motion of the box that provides the illusion. There would be the appearance of light moving at a constant angle relative to the box while the box moves at a constant speed but in a curve while the box accelerates.

You might find it interesting to calculate what a pilot would see from different directions as his spacecraft reaches a speed close to C. The interior of his craft would appear to change colors and shape and the aft parts even disappear.

46
Bob said,

It would not matter if the source of the light were inside or outside. The light does not bend. Each light wave follows a straight path away from the source. It is only the motion of the box that provides the illusion. There would be the appearance of light moving at a constant angle relative to the box while the box moves at a constant speed but in a curve while the box accelerates.


I agree with most of that, but the curvature is real relative to the man in the box.

The light source is inside the box the light would not bend because it is accelerating along with the box and there is no relativity effect. Only if the light source stationary outside the box does the relativity effect become apparent.

To an observer inside the box the bending of the light is real, but it reaches the target at the same time as when it would be straight inside the box.

IOW. the longer curved path has no effect on time as the shorter straight path would suggest.

 

47
...I wonder whether it is even necessary to be remotely related to “appear” to be identical to one of the other billions of humans who have ever lived at some appearance matching point in the pair individuals’ own development.
I missed this the first time around. And no, it is not. In a store one day, when I was still very young (early 20s or so) a friend of mine and me saw a man who looked like an older, fatter me (60s or so). He was distinctly Native American. I am not, but the similarities were still striking.

Bob, the answer to the problem you pose is relativity. The light is not traveling through “compressed space”, it’s traveling through “compressed space/time”. If space is compressed 2x, time is compressed 2x. This means that while it has to travel 2x the distance through the compressed space, time is moving at 2x the speed in that compressed space/time. Because of relativity no matter how you measure it or from where you would see it traveling at the speed of light. If you measure it going through 2x compressed space time it will cross 1x space (from your perspective) in 1x time (again, from your perspective), regardless whether you are in the same 2x space/time, “normal” 1x space/time, or a 3x space/time with a 1x space/time in between you and the 2x space/time it is traveling through. So it will always travel from point A to point B at exactly the speed of light from any perspective.

48

One interesting thing about relativity that I should note, there is a single case where you would not measure light as going at the speed of light, but taking that measurement is impossible. That instance is at the speed of light.

From the perspective of a photon creation and absorption happen at the exact same moment because at the speed of light time does not pass. So if you were to leave point A at the same time as a beam of light, accelerating instantaneously to the speed of light as light does, and stop instantaneously at point B, where the light is to be detected, to you that trip would be instantaneous and the light would have appeared to have moved, from your perspective, at infinite speed (if 0 time passes between departure arrival you get a division by zero error when doing the math of distance/time, so the speed is infinite).

However, propelling matter toward the speed of light requires increasingly large amounts of energy approaching infinity. It would take an infinite amount of energy to propel even the smallest mass to the speed of light. And even if if you were to somehow magically be propelled to the full speed of light it is theorized that you would be spontaneously converted to energy. You would become a beam of light or radiation of some sort. The magic engine which you used to propel you to the speed of light would also be just energy, no longer a physical engine capable of functioning to slow you down. And even if it could still function, since no time is passing the slowing would never be triggered and the engine would have no time to do it’s thing to slow you anyway. From the perspective of a photon there is nothing between birth and death. No distance is traveled. They are born here and die there immediately. Theoretically, anyway.

49

Write4U: “The light source is inside the box the light would not bend because it is accelerating along with the box and there is no relativity effect. Only if the light source stationary outside the box does the relativity effect become apparent.”

I suggest you get a good grasp on the fact that the motion of a light source does not add or subtract from the speed of the light emitted from that source. If it did then the speed of light would not be constant. You may want to think of it like this: the light source moves some distance, stops and emits a wave; it moves another distance, stops and emits a wave, and so on and on. Each wave is emitted from a specific point in space and it will travel in a straight line directly away from that point.

This behavior is completely opposite to bullets fired from a moving gun or drops of water sprayed from a moving nozzle. Physical objects ejected from a moving source do acquire speed from the source, but not so for light. What we may see is a change in the apparent frequency of light emitted from a moving source.

Write4U: “To an observer inside the box the bending of the light is real, but it reaches the target at the same time as when it would be straight inside the box.”

The bending of the light is not real, it is apparent, and a curve is seen only when the box is accelerating. The true path of the light is straight so of course the transit time is the same as it would be if the box were not moving.

Write4U: “IOW. the longer curved path has no effect on time as the shorter straight path would suggest.”

The apparent curved path, and the apparent angled path, are not longer, they only appear to be longer; both are straight. There is no effect on time in either case.

 

50

Widershins, I think you need to have time slowed to 1/2x in space compressed 2x in order to keep the apparent C constant. Maybe I’m wrong; this hurts my head.

Einstein is reported as meaning that nothing can go faster than C. Would it not be better to say that we cannot observe anything moving faster than C? Consider the way we measure. The fastest speed we can measure is the speed of the inputs to our measuring device. Using only touch, without the benefit of sight or hearing, we can measure speeds only as fast as we can run. Using only sound, without the benefit of sight, we can measure speeds only up to the speed of sound. Continuing the logic, we would need another input faster than C to measure speeds greater than C. Just because we can’t see or measure it doesn’t mean it doesn’t happen.

51

Nope. Compressed space = compressed time. If you have to get through 2x the space at the same speed you are going through 1x space then you need to do it in 1/2x the normal time. To do it in 1/2 the normal time you have to go 2x the speed because .5 * 2 = 1, the speed you need to appear to be going.

There are theoretical particles which can go faster than C. The tachyon is such a particle, though it has never been detected. Since time stops at C then anything moving faster than C would experience “reverse time”. It would arrive before it departed. But that doesn’t mean we would have trouble measuring it’s speed. That just means that our measurement would be backward.

As an example, let’s say I have particle Z which travels at a speed of 1.5x the speed of light. I have a machine which makes my particle, firing it at a detector at the other end. And let’s say it would take 1 second for light travel that distance. This means that my detector is going to register a hit half a second before I fire the particle. If we were able to look at that particle every step of the way it would appear as if the particle left the detector and traveled directly to my machine at half the speed of light, vanishing into the machine at the exact moment I pressed the button.

When we measure the speed of a particle we don’t do it like we do with normal speeds. We cannot “see” the particle at any point. What we can see is it’s interaction with matter or electromagnetic fields. We have to build a detector to detect when that particle arrives. Once we have that, then we can work on creating a way to produce that particle, usually in a collider. So we smash our atoms together and wait for a hit on our detector. BUT, we don’t actually know when the atoms smashed together. We can’t “see” that either. So we have a bunch of detectors, all around where we expect the collision to happen. And we use the data from those detectors, all combined together, to determine the speed at which any given particle traveled.

So, back to the problem you pose, we would not need an input faster than C to measure speeds faster than C as speeds faster than C would actually appear to be slower than C because of the time dilation. And, in fact, we don’t have any thing which moves at C because all of our equipment is made of matter and run on electrons, which are also matter. Matter cannot reach a speed of C, so it’s all slower than C. The speed is measured with math. The distance between point A and point B is X. The particle is emitted at T1 (time) and detected at T1. The speed is X/(T2-T1). If X is 186,000 miles T1 is 12:15:01:0000 and T1 is 12:15:01:0000 then the speed is 186,00 miles/second, the speed of light.

In fact, any particle which we could detect (remember, we can only detect it if it interacts with matter or electromagnetic fields) which was going faster than the speed of light would be very suspicious, even if we didn’t realize that it was moving faster than the speed of light. The reason is that it would have a constant speed which was not the speed of light. There are essentially only 2 speeds in the universe. You have the speed of light and then you have every other speed. To my knowledge there is nothing ever detected which moves at a set speed unless it is moving at the speed of light. So a particle like the one mentioned above which appeared to always move at half the speed of light would be very conspicuous. The speed of light is the only set, unchangeable speed we know of in the universe, so finding a second set, unchangeable speed would really throw physicists for a loop.

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Widdershins: “To do it in 1/2 the normal time you have to go 2x the speed because .5 * 2 = 1, the speed you need to appear to be going.”

So, are you saying that the volume of compressed space and the speed light moves through it would look like neither space nor light, nor time were compressed? If so, why would we even think there is any warp at all?

Widdershins: “Since time stops at C then anything moving faster than C would experience “reverse time”.”

Where does this idea come from?

Widdershins: “This means that my detector is going to register a hit half a second before I fire the particle.”

Do you mean appear to register?

Widdershins: “In fact, any particle which we could detect (remember, we can only detect it if it interacts with matter or electromagnetic fields) which was going faster than the speed of light would be very suspicious, even if we didn’t realize that it was moving faster than the speed of light.”

I wonder if anyone is looking for light-flash waves, supersonic boom sort of light pressure waves?

Widdershins: “The speed of light is the only set, unchangeable speed we know of in the universe, so finding a second set, unchangeable speed would really throw physicists for a loop.”

I certainly agree with that. And it would be just what we need for faster-than-light travel. I can not imagine anyone wanting to fly faster than light without some way to look out ahead a considerable distance. That would be like driving at night without headlights - possible, but not smart.

I guess the one big thing I don’t understand is how gravity, which we have been taught influences objects with mass, actually does anything to space, which supposedly has no mass, and to light, which supposedly has no mass and time which surely has no mass. How does it do it?

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So, are you saying that the volume of compressed space and the speed light moves through it would look like neither space nor light, nor time were compressed? If so, why would we even think there is any warp at all?
Bingo! And we know there is a warp because of the effects on objects and energy around it. Warp space bends light. Warped time affects clocks.
Do you mean appear to register?
Nope. I mean it's going to physically get to its destination half a second before it exists.
I wonder if anyone is looking for light-flash waves, supersonic boom sort of light pressure waves?
That's a bit of a loaded question. We look for and see "flashes of light" all the time. I assume you're talking about the flash that happens when the Enterprise enters warp, breaking the "light barrier". That wouldn't likely actually happen. The Enterprise is never actually traveling faster than light. While there would be a flash of light as you hit the speed of light (because you would be converted into it), Enterprise is really entering "subspace", not accelerating to faster than the speed of light.

Actually, the most interesting thing they’re seeing right now is extremely powerful, very short duration radio bursts at random intervals and locations. It’s the kind of very strong pulse one might see when a huge amount of energy were dumped into a device designed to break free of the constraints of space as we know it to travel great distances in short times. I’m saying it’s a warp drive signature. Well, not that it is, just that it’s fun to speculate that it might be.

I certainly agree with that. And it would be just what we need for faster-than-light travel. I can not imagine anyone wanting to fly faster than light without some way to look out ahead a considerable distance. That would be like driving at night without headlights – possible, but not smart.
That would be like driving at night while blind, and then only IF you applied Einstein's matter/energy conversion formula, E=MC^2, to every spec of dust you might hit AND changed the formula a little bit to be E=M(C*[the number indicating the multiple of the speed of light you are traveling])^2 to account for your actual speed, which is no longer the speed of light. If you hit a spec the size of the diamond in my wife's engagement ring (I was young and broke) it would be like a nuclear explosion. The nuclear fuel used to power Los Angeles loses just 6 ounces in a year's time, and that's an extremely inefficient conversion.
I guess the one big thing I don’t understand is how gravity, which we have been taught influences objects with mass, actually does anything to space, which supposedly has no mass, and to light, which supposedly has no mass and time which surely has no mass. How does it do it?
First, space is time. Space and time are the same thing, space/time. Warp one, you warp the other an equal amount. Also note, we've been using "warped" and "compressed" kind of interchangeably. They are not actually the same thing. "Warped" is the term used in physics. "Compressed" is just the way we've been thinking/talking about it, but I don't think that's really accurate.

And looking at it like gravity warps space is kind of backward. Space being warped causes gravity. In one theory, anyway. It is the warped space which bends the light. Imagine a flat piece of glass. You look through it, you see things exactly as they are. It’s a window. Now imagine bulging the surfaces out. Now things are smaller and upside down. Until you bring them near something. Then they’re bigger and right side up. That’s a magnifying glass. When we warp the glass we warp the path light travels through it (that isn’t exactly accurate, but mostly and good enough for this analogy). The same thing happens when we warp space. It’s not a flat edge between warped space and non-warped space. It’s a curved gradient. It’s easy to imagine it being like the magnifying glass, though that’s not quite accurate. It’s more like our atmosphere. In fact, it’s a lot like our atmosphere because our atmosphere essentially mimics the warping caused by our gravity. It’s thickest at the bottom, near the surface, where the most warping occurs. The further away you move, the thinner the air gets because the smaller the effect of the warp is. There is no real point where you can say, “It ends right here”. It just gets progressively thinner and thinner. So unlike our magnifying glass, there is no transitional edge where warped space “begins” and “ends”, so it’s not like we can say, “The light changes direction here”. It’s a gradual change both in and out of warped space.

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Widdershins: “And looking at it like gravity warps space is kind of backward. Space being warped causes gravity. In one theory, anyway.”

Here is another (partial) theory just for you. Gravity is a potential for a flow, somewhat like alternating current is a potential for a flow of electrons. So, what does gravity cause to flow? Matter with mass.

The second part of (partial) theory is that magnetism is also a potential for a flow. The potential is caused by the alignment of iron atoms. Each atom acts like a pump creating a lesser pressure on the inlet side and a higher pressure on the outlet side. Only when many atoms are aligned is the effect noticed. When the iron atoms are randomly oriented there is no effect.

So how is the gravitational potential created? When enough atoms are brought together they act as a sort of vacuum cleaner. A weak lesser inward pressure is generated all throughout the volume with many higher focused outward pressures occurring randomly throughout the volume. This produces only a very week gravitational effect. When the mass rotates the outward potentials are focused at both poles and the inward potentials become noticeable around the surface of the volume. The outward potential effect can be seen as jets at quasars.

As I mentioned, this theory is just for you. I don’t want anyone else building a gravity engine before I can get mine patented. :slight_smile:

55

Don’t worry. I don’t think many people read this stuff. What might one do with a “gravity engine”?

56

TimB: “What might one do with a “gravity engine”?”

Well, if we discover that the rate of propagation of gravity waves (G, the speed of gravity) is faster than the speed of light we just might use that to get to warp speed and beyond. I saw a suggestion many years back that G might be as much as C x 10^23. If so then we might be able to reach warp 12 (C x 10^12) theoretically and warp 7 (C x 10^7) safely, the minimum speed we would need to explore other galaxies and get back within a normal lifetime.

57

First, I would like to state that I believe one of the formulas I gave was flawed. The formula E=MC^2 is used to calculate the maximum amount of energy a mass can be converted into. The speed that mass is going has no effect on that formula. However, I believe this formula is at least one reason it is believed that accelerating a mass to the speed of light will spontaneously convert it into energy. So the speed of light in the formula says how much energy the mass can be converted into and has nothing to do with speed of travel. Speed of travel would be additional, separate energy besides what the mass can become.

And you’re too late on the gravity engine. Futurama did it years ago and they weren’t the first. And I’m pretty sure gravity waves travel at the speed of light. They have finally been detected, just within the last decade or so. There was something unexpected about them, though I don’t remember what, exactly. I think it was the timing of their detection vs the timing of the detection of some other component of large masses merging. Maybe they didn’t arrive here at the same time, but should have? I can’t remember.

58

I have a question that nobody seems to be able to answer so hopefully this forum will be able to help. If we are ever able to achieve time travel would the space that we occupy at the start of time travel would it be occupied while traveling through time. If so would this have disasters effects. If an object is in the same space while going through time would it not harm or kill the person traveling through time and destroy the object it collides with?

Many Thanks

59

AFAIK ANTONY, that is the problem with time travel. You can’t just pop some matter into existence. The sci-fi series “Travellers” solved the problem by beaming back in time only the programming of the brain. They had all the records of when people died, so they would beam into a person who was going to die anyway, then avoid getting killed, avoiding moral issues as well.

60

Antony, given that time travel is only theoretical, and actually impossible by some models, there is no answer to that question which isn’t 100% made up. There are no “answers” in time travel currently, only science fiction.