These physicists know nothing about time travel

[Widescreen]

http://www.foxnews.com/story/0,2933,258279,00.html


"If you want to know what the Earth is like one million years from now, I'll tell you how to do that," said Greene, a consultant for "Déjà Vu," a recent movie that dealt with time travel. "Build a spaceship. Go near the speed of light for a length of time — that I could calculate. Come back to Earth, and when you step out of your ship you will have aged perhaps one year while the Earth would have aged one million years. You would have traveled to Earth's future."
B.S.

You only have to go 88mph.

[olevetonahill]

Which makes me wonder
If your driving at the speed of light
and Turn On the headlights , What happens ?

[1stTimeCaller]

Which makes me wonder
If your driving at the speed of light
and Turn On the headlights , What happens ?

STFU

:D

[olevetonahill]

STFU

:D
Whats the matter ? that question to deep for ya ? :P

[SoonerBorn]

Hiro just has to squish his face. Hiro > BTTF.

[landrun]

http://www.foxnews.com/story/0,2933,258279,00.html


B.S.

You only have to go 88mph.

And you'll need a flux-capacitor. Don't forget the flux-capacitor. http://www.soonerfans.com/forums/images/icons/icon14.gif

[Tulsa_Fireman]

I'm no physicist. I'm no math ninja. But I got a question.

If mass can neither be created nor destroyed as per Conservation of Mass/Energy, why would mass increase exponentially as one approached the speed of light? Wouldn't the speed of light simply be just that? A velocity that can be approached and exceeded, just like the speed of sound?

Can anyone explain this in layman's terms?

[Newbomb Turk]

I'm no physicist. I'm no math ninja. But I got a question.

If mass can neither be created nor destroyed as per Conservation of Mass/Energy, why would mass increase exponentially as one approached the speed of light? Wouldn't the speed of light simply be just that? A velocity that can be approached and exceeded, just like the speed of sound?

Can anyone explain this in layman's terms?

it would help if you'd start by asking the question in laymans terms.

;)

[Ike]

I'm no physicist. I'm no math ninja. But I got a question.

If mass can neither be created nor destroyed as per Conservation of Mass/Energy, why would mass increase exponentially as one approached the speed of light? Wouldn't the speed of light simply be just that? A velocity that can be approached and exceeded, just like the speed of sound?

Can anyone explain this in layman's terms?

a) mass is created and destroyed all the time. It's our specialty here.

b) mass remains constant. It is what we call a Lorentz invariant quantity, which means that the speed something is traveling has no bearing on it's mass.

c) speed of light is totally different beast than the speed of sound. The only thing that can even get to the speed of light is something that has no mass (like say, light). If something has mass, it can't ever even get to the speed of light. ever. Part of the reason has to do with the funny way that time is intertwined with space. Time actually slows down as you move faster.

[OCUDad]

I was SO just about to say that.

[Ike]

Which makes me wonder
If your driving at the speed of light
and Turn On the headlights , What happens ?

you'd never notice the difference.

other than maybe the fact that you may not be able to see anything in the headlights due to extreme blueshifting.

the bizarre thing about the speed of light is that no matter how fast you are going, the speed of light is the same.

[Tulsa_Fireman]

Thanks, Ike! I hoped someone would step up and shed a little "light" on the subject. *cue groans*


The only thing that can even get to the speed of light is something that has no mass (like say, light).

This is the kicker, then. I've always heard it explained as mass increasing as speed increased until mass in and of itself increased to the point of making light speed travel impossible, which in turn didn't groove with why the mass would increase in the first place.

Thanks again.

[Ike]

Thanks, Ike! I hoped someone would step up and shed a little "light" on the subject. *cue groans*



This is the kicker, then. I've always heard it explained as mass increasing as speed increased until mass in and of itself increased to the point of making light speed travel impossible, which in turn didn't groove with why the mass would increase in the first place.

Thanks again.

the thing is, the mass stays the same, but the energy in an object going near the speed of light can be huge. In fact you can keep adding as much energy as you want, but near the speed of light, you won't see much of an increase in speed. I think some people may then insert E=mc^2 into that and claim that the mass therefore increases. This is an incorrect interpretation of that equation. In fact, that equation is only part of the relativistic energy of any object. The full equation is E^2 = m^2*c^4 + p^2*c^2 where p is an objects momentum. So E=mc^2 only refers to the rest energy of an object (ie, when it's momentum is zero)

[Ike]

I should add for the sake of completeness that there is an interpretation that mass does increase with increasing speed...however, this requires that mass be re-defined a bit....but still if you were going super fast, you would have no idea that you gained any mass.

The more common convention is to instead re-define momentum so that at speeds much lower than the speed of light it is still the p=mv that you learned in kindergarten physics, and at higher speeds it is the thing that blows up near the speed of light instead of the mass.


both of these conventions are still using the same laws of physics...they just make different choices about where the "proper" place to put an extra term should be. It's semantic really, but there are very few physicists who will make the choice of putting the extra term into the mass because it's just not something that makes a whole lot of sense when you try to explain it to everyday people. Of course, I'm not sure why we care about things like making sense explaining physics to everyday people when there are maybe only 10 people in the world that can make sense out of quantum mechanics.

[Tulsa_Fireman]

Of course, I'm not sure why we care about things like making sense explaining physics to everyday people when there are maybe only 10 people in the world that can make sense out of quantum mechanics.

Because we're curious. And we want you to share your stuff.

It'd be the same thing if someone came to me and said, "Justin, how'd you get to such an Antonio Banderas level of sexy?" I'd share, not because they have a chance of obtaining such a level of The Sexy, but because I want to share and help them with their curiosity.

I think. Something like that.

[SCOUT]

The more common convention is to instead re-define momentum so that at speeds much lower than the speed of light it is still the p=mv that you learned in kindergarten physics...
Kindergarten!?!? You must have been in the remedial class ;)

[NormanPride]

So since I type on soonerfans.com so much, and my fingers go, like, super fast... are they younger than the rest of my body?

Also, are people living longer now because we drive in cars a lot more and the world ages faster around us? :D

[Xstnlsooner]

Very interesting stuff Ike. Not that I understand it, but it does
intrigue me. I've read some of Hawking's books, but most of
it is way over me head. I know I'm NOT of those ten you're
talking about.

[Vaevictis]

Kindergarten!?!? You must have been in the remedial class ;)

Heh, that's one of my favorite things about physics and math. You take all of this stuff for the first two years in college, and when you get into the third year stuff, they really ought to have a prof come in and tell you, "Oh yeah, all that stuff we've taught you in the past two years... it's all bull****. I mean, I guess it works for simple stuff, but we're going to ****can it all now, because it just doesn't ****ing cut the mustard anymore. d-theta is large now."

[Ike]

So since I type on soonerfans.com so much, and my fingers go, like, super fast... are they younger than the rest of my body?

Also, are people living longer now because we drive in cars a lot more and the world ages faster around us? :D


yep. Every year the average American adds .0179 seconds onto his life just due to car travel. And another 0.0398 seconds due to airplane travel.

It may seem like small potatoes, but it adds up.

[Ike]

Heh, that's one of my favorite things about physics and math. You take all of this stuff for the first two years in college, and when you get into the third year stuff, they really ought to have a prof come in and tell you, "Oh yeah, all that stuff we've taught you in the past two years... it's all bull****. I mean, I guess it works for simple stuff, but we're going to ****can it all now, because it just doesn't ****ing cut the mustard anymore. d-theta is large now."

It's all part of the master plan to suck the life out of otherwise promising young minds. :D

[1stTimeCaller]

Has anyone asked Dr. Indestructo about this?

[Ike]

Kindergarten!?!? You must have been in the remedial class ;)


nah...just an underfunded public school.

[SoonerBorn68]

Has anyone asked Dr. Indestructo about this?

Heh, we took the kids to see him the other night. The dude gargled liquid nitrogen. :eek:

[landrun]

a) mass is created and destroyed all the time.

b) mass remains constant.


To my unlearned mind, that seems like a contradiction. :)

The only thing I have to compare this too in real life is my wife getting fatter and fatter but yet she claims to weigh the exact same as she did when we first got married. ;)

[SoonerBorn68]

To my unlearned mind, that seems like a contradiction. :)

The only thing I have to compare this too in real life is my wife getting fatter and fatter but yet she claims to weigh the exact same as she did when we first got married. ;)

You put that winkie there, but if she reads this you're matter will be destroyed--painfully. :D

[NormanPride]

Ba-zing!

[Ike]

To my unlearned mind, that seems like a contradiction. :)

The only thing I have to compare this too in real life is my wife getting fatter and fatter but yet she claims to weigh the exact same as she did when we first got married. ;)

ok, so I was talking about two different situations.

matter can certainly be created and destroyed. When I said that mass remains constant, I meant that under a change of reference frame, the mass of an object does not change (ie, speeding up or slowing down doesn't change the mass of an object). I did not mean that the total mass of the universe is a constant. The total energy of the universe however, is a constant.

[OKC-SLC]

Ike, when are you going to tell everyone that i've been feeding you all your physics answers on the boards for all these years?

[Ike]

Ike, when are you going to tell everyone that i've been feeding you all your physics answers on the boards for all these years?

in about a month or so.

[OKC-SLC]

nice.

[Tulsa_Fireman]

If you'd have typed that faster, you'd get it 0.018 seconds quicker.

[OCUDad]

in about a month or so.About the same time you admit you're really a taxi driver in Des Moines?

[IB4OU2]

So if I was travelling around the universe for a year going 186,000 miles a second and fell out of the cockpit onto planet earth my brother would be over a million years old?

[yermom]

well, to you it would feel like a year

and you would only have to go a percentage of that speed to have something similar happen