Dumb scifi question

[SeanRonJohnson]

I was watching that movie Clockstoppers, where some kids slow down time around them by speeding up their molecules with a special watch.

Now from what I've gathered anything in motion is moving through time slower than anything stationary, it's just we move so slowly the difference is highly insignificant, but if we moved near the speed of light then the difference in time passage would be noticable. If electrons are excited and start spinning faster, that means the object is sort of moving slower throught time on a molecular level. Doesn't that pretty much conflict with the theory in the movie?

I probably shouldn't let such things bug me, but they do.

[Lobsang]

I could never get my head around the idea that things moving close to the speed of light age slower than things not. The explanations seem to talk about not seeing what is really happening because the light has taken a noticable amount of time to get to me, and therefore the light I am seeing is not what is happening to the object at that moment in time. Surely the 'time' of an object is irrelevant to what it's light is doing. I can't understand how a thing travelling very fast could possibly alter it's time relative to things not.

Sorry, that's not an answer to the OP.

[eburacum45]

Ahh, but you see, it was a special watch;

special watches can do anything.

I think you are right though;

from memory, Stephen Baxter in his book 'Time' points out that the electrons in gold atoms move particularly fast, so they undergo time dilation;

he says that is the explanation for the colour of that metal...

so speeding up atomic movement does slow down the time of those atoms.
But not the time of somebody simply holding those atoms...

[Padeye]

GR is a bit much to wrap your brain around and scifi movies with bad physics won't help. Time dilation is real and has been experimentally proven by taking an atomic clock on a commercial flight around the world and comparing it to another similar clock in a fixed location. It may help to think of a time-space continum as time and space are not two different things but two aspects of the same thing and both dilate when moving relative to an observer. This accounts the speed of light in a vacuum being the same for all observers as in the Mitchelson-Morley experimentexperiment.

[Lobsang]

I am sorry if this is really ignorant... Are you saying that it is merely a co-incidence that light does weird things at hight speeds as well as time.

When reading theories of General relativity they seemed to suggest that light was responsible in some way for the time-shift.


If a (very powerful) torch pointing at me could travel away from me at the speed of light what would I see (over time)?

[NoClueBoy]

Originally Posted by Lobsang

If a (very powerful) torch pointing at me could travel away from me at the speed of light what would I see (over time)?

It would be red shifted well below your eye's visibilty threshold. So, it would appear to you to not appear at all.



Unless you wear these special glasses!

[hawkeyejo]

Originally posted by Padeye

GR is a bit much to wrap your brain around and scifi movies with bad physics won't help. Time dilation is real and has been experimentally proven by taking an atomic clock on a commercial flight around the world and comparing it to another similar clock in a fixed location. It may help to think of a time-space continum as time and space are not two different things but two aspects of the same thing and both dilate when moving relative to an observer. This accounts the speed of light in a vacuum being the same for all observers as in the Mitchelson-Morley experimentexperiment.

WHAT????

Can you explain that in English?

[Lobsang]

Originally Posted by NoClueBoy

It would be red shifted well below your eye's visibilty threshold. So, it would appear to you to not appear at all.



Unless you wear these special glasses!

Alright. Suppose I could detect a wide enough range of light. My point is - does the light traveling out of the torch still travel at the speed of light relative to me? relative to the torch? Or both?

[NoClueBoy]

Originally Posted by hawkeyejo

WHAT????

Can you explain that in English?

Ya pull the plug!




To Lobs, if the speed of light (C) is truly a constant, than it remains constant, not relative to anything else. The contancy of C is one of the basics of classic general relativity. (everything else was relative to it, you see...)

So, if I'm interpreting it right, you would still see it.

Now, I sit and wait for someone to explain the real answer for us.

[Sengkelat]

Originally Posted by Lobsang

Alright. Suppose I could detect a wide enough range of light. My point is - does the light traveling out of the torch still travel at the speed of light relative to me? relative to the torch? Or both?

Both. The speed of light is the same regardless of your frame of reference.

Einstein had a thought experiment that went something like this: Assume you have two perfectly reflective mirrors facing each other, one mounted under your nose facing down and the other mounted atop your beer gut facing up. Assume there's a beam of light bouncing back and forth in between them, in perpetuity. You've calculated that the light will bounce back and forth exactly one zillion times every second. And you're moving forward at a certain (very fast) speed. Everything seems normal to you. I mean, aside from having mirrors stuck to you and all.

Your friend, though, is not moving, and is observing you. What he sees is not a beam of light bouncing perpendicularly to the mirrors. Because you're moving, he sees the beam traveling in a zigzag between the mirrors. So he sees the beam, instead of traveling just from beer gut to nose, traveling a diagonal from where your beer gut is now, to where your nose is when you've moved a bit. (This is hard to explain without a diagram, sorry) So he sees the beam of light travel further than you do. Now, if this were a ping-pong ball bouncing back and forth, your friend would see the ball moving between the mirrors and its speed would just appear faster to him than it does to you. But the speed of light is the same no matter your frame of reference. So your friend sees the beam of light moving further between mirrors, but at the same speed -- so to his eye, the beam doesn't bounce back and forth exactly 1 zillion times per second. But you've already told him that it does; so he concludes that time is moving more slowly for you.

Okay, was that completely confusing?

The question I have is why oh why is the speed of light the same regardless of your frame of reference? I clearly don't have a proper grasp of Maxwell's equations.

[Chronos]

Light always travels at the same speed because it travels at c. I'm afraid that there is no real "why" to that; it's just one of the fundamental properties of the Universe.

And eburacum45, do you think you could look up a cite for what you're saying about gold? Because it looks pretty nonsensical from here. Electrons in an atom never travel particularly fast ("particularly fast" meaning here "near the speed of light"), and even if they did, I fail to see how that would affect the color of a substance.

[Diz]

I'm not going to touch the "why", but maybe this will help you visualize what is happening at least.

I don't remember where I read this, but hopefully I won't mangle it too badly. It helps if you are familiar with vectors I suppose. You travel though space-time at a constand speed, always, without exception. You are travelling at that speed right now. You can travel forward in the time dimension and you can physically move in the spatial dimensions. The addition of these two velocities is always the same. It becomes obvious then that the faster you travel in the spatial dimensions, the less velocity is left over to move forward in time, so that once you reach maximum speed, C, time has stopped completely.

I know thats a bit simplified and I'm probably leaving some important stuff out. I like to think I have a decent grasp of this kind of thing, but it's still hard to put into words. If you're really interested I'd recommend taking a look at Brian Greene's book, "The Elegant Universe" for some good explanations

[eburacum45]

Sorry, Chronos, but I only have Mr Baxter's word for this;

anal-retentive that I am,
I have a reasonably long list of errors in Baxter's writings; believe me, it is a lot shorter than the list of errors in my own.

Perhaps this is not one of them:

On a whim, she...looked up the properties of gold.
She learned that relativistic effects, the strange and subtle effects of very high speeds and energies, determined the colour of gold.
In light elements, electrons orbited the nuclei of atoms at a few hundred miles per second; fast, but only a few percent of the speed of light. But in elements with massive nuclei, like uranium, lead, or gold - the electrons were dragged around at a large fraction of the speed of light, and relativity effects became important.

Time (1999)

how's that?

[Vaeth]

Just wondering, is it possible that light appears to travel at the same speed regardless of your frame of reference because if it were travelling faster, we wouldn't be able to see it to measure it?

What I am trying to say is, we measure light using light itself (i.e. what we can see, or, detection of photons) so it would be impossible for us to measure an object that was going faster than light since we are using the very light from the object we are trying to measure to measure the object's speed. How would we know if an object was travelling faster than the speed of light if we are relying on the light coming from that object to determine how fast it was travelling?

Assume that I was in a UFO and I travelled at 10x speed of light away from you for a distance of 10 light years. Now further assume that the only light source in the universe is a gigantic torch shining in the direction my UFO is travelling and which is right next to you. Even if I reached my destinantion in just 1 year (i.e. I was really travelling at 10x speed of light) you would have no way to know that I had reached my destination until at least 20 years later ( 10 years for light from the torch to travel to where I am + 10 years for the light reflecting off my UFO to get to you) which leads you to conclude that my maximum speed was 1x speed of light. So despite any protest on my behalf insisting that I travelled at 10x speed of light, scientists back home would simply say that time slowed down for me and that what seemed like 1 year for me was actually 10 years.

If there was a spectator at my destination, and assuming there was a light source at his end pointed towards my approaching UFO, then chances are he would see my UFO just suddenly appear in front of him, and then see my UFO stretch in reverse away from him as the rest of the light (which reflected off my UFO while I was approaching) catches up.

If you were standing still, and I approached you at 10x speed of light, how fast would it seem like I was approaching you? If you were measuring my speed using your eyes (or a photon detector) then of course, I would only appear to be travelling at the speed of light.

I just can't help but feel that the scientific community, perhaps due to its inherent inertia, does not "rock the boat" enough when it comes to relativity and faster than light travel.

[robo99]

Originally Posted by Jonathan D

I'm not going to touch the "why", but maybe this will help you visualize what is happening at least.

I don't remember where I read this, but hopefully I won't mangle it too badly. It helps if you are familiar with vectors I suppose. You travel though space-time at a constand speed, always, without exception. You are travelling at that speed right now. You can travel forward in the time dimension and you can physically move in the spatial dimensions. The addition of these two velocities is always the same. It becomes obvious then that the faster you travel in the spatial dimensions, the less velocity is left over to move forward in time, so that once you reach maximum speed, C, time has stopped completely.

I know thats a bit simplified and I'm probably leaving some important stuff out. I like to think I have a decent grasp of this kind of thing, but it's still hard to put into words. If you're really interested I'd recommend taking a look at Brian Greene's book, "The Elegant Universe" for some good explanations

This seems to imply that the sum of the two velocities is always C. Are you saying we are traveling through time-space at C?

[Diz]

Originally Posted by robo99

This seems to imply that the sum of the two velocities is always C. Are you saying we are traveling through time-space at C?

Well, C is only a measure of velocity in the spatial dimensions, so it would have no meaning in the time dimension, but that is the basic idea I think...

Someone more knowledgeable than I could probably explain it more accurately

[Sublight]

Originally Posted by Lobsang

If a (very powerful) torch pointing at me could travel away from me at the speed of light what would I see (over time)?

Let's say that the torch starts moving away slowly, and then accelerates faster and faster, approaching the speed of light.

As the torch moves away, the color of the light would start to be shifted toward the red, or longer-wavelength, end of the spectrum. If your torch started by shining just violet light, the color would start to apppear blue, then green, yellow, orange and finally red before becoming invisible infrared light as the torch reached a certain speed. As it accelerated, the wavelengths would get longer and longer, through microwaves and radiowaves.

As for what happens when the torch is moving away at the speed of light, I can really only hide behind the rule that an object with mass can't travel at the speed of light. Still (just speculating here), long-wavelength photons have less energy than short-wavelength ones, so a photon emerging from a source moving away at c would therefore have an infinitely long wavelength and zero energy, so you wouldn't be able to detect it at all.

[Jinx]

Originally Posted by SeanRonJohnson

...If electrons are excited and start spinning faster...

First of all, electron spin is NOT to mean they are actually spinning, IIRC. It is just a characteristic of the electron described as either (+) or (-). It is no more an actual spin than, say, subatomic particles HAVE charm. These are merely terms from quantum physics not meant to be applied literally. You may also recall the spin is a quantum value, and no two electrons of an atom can have the same quantum numbers. So, IIRC, two electrons sharing the "s" orbital can have all the same quantum numbers EXCEPT their respective spins will be equal and opposite.

Also, electrons move at the speed of light about the nucleus of an atom, IIRC. They are presumed to be massless, although I believe they are said to have a rest mass value. {Hmm...if this is true, why don't they turn into energy, either in part or total, when moving at c?}

Just my recollection from various physics and chem courses...
- Jinx

[Padeye]

Originally Posted by Jonathan D

Well, C is only a measure of velocity in the spatial dimensions, so it would have no meaning in the time dimension, but that is the basic idea I think...

No, but not for the reason you think. Velocity is an instantaneous measurement at one point in space/time but we need to express it in distance/time the same as we do for speed which is an average measure of distance travelled in a given time.