Going the Speed of Light

[JBCM627]

Completely False kian.

No, completely true.

http://math.ucr.edu/home/baez/physics/Relativity/SR/velocity.html

This doesn't hold if space itself is expanding (which is thought to be the case with our universe). This might be what KYLE is talking about, but this is something completely different than traveling faster than light in a universe that isn't expanding, and thus isn't considered in special relativity. It also probably isn't something people should think about if they don't understand special relativity first. Most accurately put, objects with mass can't accelerate to the speed of light.

 

[Ellis]

To be fair, he didn't specify a frame of reference.

True, but I should have specified.

 

[brunson]

Completely False kian.

No, completely true.

http://math.ucr.edu/home/baez/physics/Relativity/SR/velocity.html

This doesn't hold if space itself is expanding (which is thought to be the case with our universe). This might be what KYLE is talking about, but this is something completely different than traveling faster than light in a universe that isn't expanding, and thus isn't considered in special relativity. It also probably isn't something people should think about if they don't understand special relativity first. Most accurately put, objects can't accelerate to speeds faster than light.

I was avoiding the issue of expansion, trying not to muddy the waters.

 

[JBCM627]

I was avoiding the issue of expansion, trying not to muddy the waters.

Probably a good plan.

Edit
(Btw, that wasn't intended as a slap to you, but to people like xdaveXxthing)

 

[Kyle™]

We'll see who can run faster than light when I get my cheetah leg implants. WATER'S GETTIN' MUDDY.

 

[nitrocan]

Oh, this is why my timer kept showing 0.02. I'll go slower from now on.

 

[miniGOINGS]

This raises another question of mine:

When moving faster than the speed of sound, can you hear anything? I doubt it, but I've never done it, so I have no idea.

The speed of sound depends on the density of air pressure, which effects the speed at which sound travels. If you were going faster than the speed of sound, and sound behind you would not catch you but sound in front of you would hit you faster.

If you listen to an ambulence, the sound gets higher pitched as it's coming towards you, and lower pitched as it's going away from you.

...I think...

 

[nitrocan]

This raises another question of mine:

When moving faster than the speed of sound, can you hear anything? I doubt it, but I've never done it, so I have no idea.

The speed of sound depends on the density of air pressure, which effects the speed at which sound travels. If you were going faster than the speed of sound, and sound behind you would not catch you but sound in front of you would hit you faster.

If you listen to an ambulence, the sound gets higher pitched as it's coming towards you, and lower pitched as it's going away from you.

...I think...

Your first argument was correct but what does the ambulance thing have to do with anything?

 

[miniGOINGS]

Your first argument was correct but what does the ambulance thing have to do with anything?

Thank you .

Let's say that you were moving, not the ambulance. If you kept moving directly away from the ambulence, faster and faster, by the time you got to the speed of sound, you wouldn't hear the ambulance, but you would still be able to hear things that are in front of you or at an angle although the sound would be distorted.

...I think again...

 

[nitrocan]

Your first argument was correct but what does the ambulance thing have to do with anything?

Thank you .

Let's say that you were moving, not the ambulance. If you kept moving directly away from the ambulence, faster and faster, by the time you got to the speed of sound, you wouldn't hear the ambulance, but you would still be able to hear things that are in front of you or at an angle although the sound would be distorted.

...I think again...

But that's because the sound is dying, not disappearing.

 

[qqwref]

Oh, this is why my timer kept showing 0.02. I'll go slower from now on.

Yes, you should indeed go slower, always wait at least a second before lifting your hands away from the timer ;-)

 

[Carson]

I have no physics background, or any real knowledge. Here is what I "think" I can take away from this conversation... someone please correct me if I am wrong:

Two objects are moving in opposite directions, each at .75 the speed of light... in reality, the distance between them would be increasing at almost the speed of light, because there speeds would be combined, however due to both objects having mass, their combined speed still cannot reach the speed of light.

If two photons were moving away from each other, each at .75 the speed of light, then they would really be moving away from each other at exactly the speed of light due to them having no mass.

If two objects are moving away from each other, each at .75 the speed of light, then they would appear to be moving away from each other at 1.5x the speed of light from an observer.

Is this even close, or am I missing the whole point?

 

[brunson]

There are some really good books on introductory relativity, my dad had one that I read when I was about 12, then again when I was 14 and again when I was in college. You seem really receptive to the concepts, so I'll respond.

You can start with only one fundamental: The speed of light (in a given medium) is constant in all frames of reference. No matter what, the speed of light is always constant.

I have no physics background, or any real knowledge. Here is what I "think" I can take away from this conversation... someone please correct me if I am wrong:

Two objects are moving in opposite directions, each at .75 the speed of light... in reality, the distance between them would be increasing at almost the speed of light, because there speeds would be combined, however due to both objects having mass, their combined speed still cannot reach the speed of light.

Yes, but not exactly for the reason you describe.

If two photons were moving away from each other, each at .75 the speed of light, then they would really be moving away from each other at exactly the speed of light due to them having no mass.

This is hard to say yes or no to. A photon begins its existence at the speed of light and ends it the same way. Time really has no meaning to photon. It boils down to the time dialation of a particle equals it's mass divided by the the square root of the quantity, speed of light minus its velocity. This is zero divided by sqrt(c minus c) or zero over zero. The c's may be squared, but it doesn't matter, it's still zero over zero.

Essentially, everything breaks down *at* the speed of light, so we can only discuss what happens close to the speed of light.

If two objects are moving away from each other, each at .75 the speed of light, then they would appear to be moving away from each other at 1.5x the speed of light from an observer.

No.

Is this even close, or am I missing the whole point?

I'm sorry, writing this I realized I don't have nearly the time, nor the *skill* to explain this in a reasonable post, but please don't think I ducking the issue. There is a *ton* of stuff on the subject on the 'Net. Google "special relativity paradox" and grab a snack because you'll be in for a really enjoyable next three hours.

 

[wing92]

i want to take a shot at understanding this. let's say there's a special gun that shoots two rounds opposite directions at .75 times the speed of light. the relative velocities of the two things can only be up to the speed of light. normally they would add up to 1.5 times the speed of light. to fix this problem, given the equation speed=distance/time, and the distance isn't relative (i think) then the time has to change. the speed goes down (i know there's a better way of wording that but you get what i mean) and the time goes up, but the amount of time only goes up for those two bullets. so the two bullets would age faster than the guy that shot the gun. how close am i?

 

[imaghost]

i want to take a shot at understanding this. let's say there's a special gun that shoots two rounds opposite directions at .75 times the speed of light. the relative velocities of the two things can only be up to the speed of light. normally they would add up to 1.5 times the speed of light. to fix this problem, given the equation speed=distance/time, and the distance isn't relative (i think) then the time has to change. the speed goes down (i know there's a better way of wording that but you get what i mean) and the time goes up, but the amount of time only goes up for those two bullets. so the two bullets would age faster than the guy that shot the gun. how close am i?

Opposite. The bullets would not age as fast relative to you. The bullet would appear to be going very slow.


With the speed of light and relativity, I have always wondered if you can make light go faster than, well, light. If you can slow it down, can you speed it up? Black holes, if you don't know, they are basically really massive that even light cannot escape its gravitational field. General Relativity would make it to where the dip goes to a point, and that is why some people think they can send things to other places, transporter thingies. anyway, with that being said, what if I shine a flashlight on black hole? would the gravitational pull make the light go faster?

I do realize it probably will not, since light is a constant, which is the only answer that I have gotten to this question, by a former Physics teacher, but now why can light go slower since it is a constant?

 

[wing92]

it's a constant as long as what it's going through is constant. hopefully i got that much right. also, how does the whole relativity thing change when wormholes are added?

 

[4Chan]

http://www.universetoday.com/2009/06/30/device-makes-radio-waves-travel-faster-than-light/

Faster than light phones? I dont really trust the media completely.
I thought this was impossible when i saw it a few months back.

What do you all think of it?

 

[imaghost]

BS, didn't have to read it, just the title. Radio waves are light. Impossible to go faster than light, since it is light.


Worm holes and black holes are different.

 

[JBCM627]

Sure, I can make things travel faster than light too. Just take a laser, point it at one star, then quickly point it to another. The end of the beam moves faster than light.

 

[imaghost]

That is wrong in so many ways... it is not moving in a line across. The photons have a forward motion, not a side motion...