# Einstein got it all wrong?

Discussion in 'Physics & Math' started by scifes, Mar 26, 2011.

1. ### scifesheckle the snobsValued Senior Member

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ok, i'm really hyped for this, cuz i'm either going to break Einstein's work in two, or i'm about to learn something wondrous(of how my "theory" is wrong).

ok, now according to e=mc^2, when a body goes the speed of light, it totally becomes energy, or light, so presumably humans can't withstand going the speed of light so they'll die.

BUT....
velocity is relative, it's not absolute relative to earth, so we surely are going the speed of light with respect to a certain point in some other galaxy, yet we haven't dissolved into light.

ALSO, it is a scientific fact that things can't go faster than the speed of light, BUTTTTTT:
if two things were going he speed of light in opposite directions, wouldn't both be going double the speed of light relative to each other?

WELL, AIN'T I SMART AND INGENIOUS? ME WANTS A NOBEL PRIZE! ME WANTS A NOBEL PRIZE! and don't any of you dare try stealing my revolutionary discovery!:grumble:

3. ### ULTRARealistically SurrealRegistered Senior Member

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Sorry to have to break it to you buddy, but it's been thought about before. In fact, two objects only have to diverge at half the speed of light to be diverging at 1x C. The light from one object would therortically never reach the other. Since information about each other can never reach each other, they have to be considered as independant entities. They are then only travelling locally at thier own speed, the speeds are not cumulative. I'm sure someone much smarter than me can explain this scientifically, but I believe I am basically correct.

5. ### OnlyMeValued Senior Member

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At least to some extent the issue you raise confronted phycists long long ago. It was resolved at least in theory.

Think about the red shift observed in light. In the beginning it was considered to be due to distant galaxies etc. Moving away from "us" at a significant fraction of the speed of light. The problem was that as we began to see further and further objects the relativistic velocities became theoretically impossible. The solution was the expansion of space itself. As space expands at a constant non-realitavistic velocity, the little comparritive slow expansion of local space is observationally compounded by the total slow expansion over great distances.

Think of it this way and only as an example...

All of space is expanding at 1 meter per minute. From any point in space if you observe two points, one a meter from you and the other two meters. The first will appear to be moving at 1 meter per minute away, but the second will appear to be moving twice that. 1 meter for the distance to the first point and another for the distance to the second.

Since it is space that we say is expanding neither are actually moving, space is.

I probably mangled that badly but maybe the point can be dug out....

Since it is space itself that is expanding a litte here and a little there, nothing in space is actually moving faster than the speed of light.

the red shift comes from the wavelength of light being stretched out by that expansion of space.

7. ### Janus58Valued Senior Member

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1,785
That's not what E=mc² means. It means that the conversion factor between the energy equivalence and the rest mass of matter is c², or in other words, if you were to convert a mass of 1 kg to energy, you would get
89875517873681764 joules of energy. It has nothing to do with any body moving at the speed of light.
velocities don't add like that, but by
$V_t = \frac{v_1+v_2}{1+\frac{v_1v_2}{c^2}}$

if v1 and v2 both equal c, you get an answer of c.
(Note that if v1 and v2 are small compared to c, like they are with the type of speeds we deal with every day, then the answer comes out to be very very close to v1+v2, which is why it took us so long to figure out that v1+v2 is not the proper way to add velocities)
Sorry, not worth stealing, as it isn't even an original misunderstanding. I wish I had a dollar for every time I've heard these exact same arguments.

8. ### Captain KremmenAll aboard, me Hearties!Valued Senior Member

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Yes, $V_t = \frac{v_1+v_2}{1+\frac{v_1v_2}{c^2}}$

And that's putting it simply.

9. ### DywyddyrPenguinaciously duckalicious.Valued Senior Member

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It might help if you'd actually learnt some physics before embarking on this post.

It's always a good idea to have at least some clue as to what you're talking about.

10. ### scifesheckle the snobsValued Senior Member

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i know, but what if they were diverging both at the speed of light, then it would be 2c.

also, don't think of them going away from each other, think of them heading towards each other.
that's very interesting. can you elaborate? is there a name for this "decision", a theory or something?

so you cannot measure a velocity of a body going at the speed of light in one direction relative to another similar body in the opposite direction, it's just not allowable scientifically?

very interesting, but how does it resolve two opposite projectiles at the speed of light?

11. ### scifesheckle the snobsValued Senior Member

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2,561
yeah i know there's another dude who discovered that the frequency of a body is proportionate to its mass and velocity.
but putting E=mc^2 seemed much cooler

proCESSING.................................

i'm sorry, it's like you're telling me 1+1 doesn't equal 2?

i could give you a dollar for explaining that to me i would've given you five.
however, all i can offer is a sincere thank you

i can see the math works.
but what the heck does it mean?

12. ### scifesheckle the snobsValued Senior Member

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there's no point in learning before you ask if you're asking to learn.

i do, i was excellent in dynamics.

13. ### OnlyMeValued Senior Member

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I thought you were asking about real possibilities. The expansion of space is the only thing that I can think of that comes close to looking like relitavistic velocities with real objects.

If you are asking about a real possibility, you could not generate enough force to accelerate any object with mass to anywhere near the speed of light. Other than single particles or ions in say the LHC. But the mass is very small and attempting to run at full power over the winter would deprive Geneva of the power to heat houses.

Both neutrinos and photons have relitavics velocities. The neutrino being just short of the speed of light. Two photon's moving toward each other close the distance at 2c, but they are in different frames of reference and have no rest mass. Neutrinos could be assumed to come close. But in neither case does a photon or a neutrino exceed the speed of light itself.

If you have two cars moving toward each other at 60 MPH or KPH they close the distance faster than either is moving. But neither one gets where they are going faster.

Until someone figures out warp drive or hyperspace drive it just ain't gonna happen.

14. ### Captain KremmenAll aboard, me Hearties!Valued Senior Member

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I've not heard that before.

15. ### DywyddyrPenguinaciously duckalicious.Valued Senior Member

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Correct.
And if you're going to learn you should at least grasp the basics. That's what I meant.
For example:
Indicates that you don't know what you're talking about, and
Indicates that you're not bothered about correct or incorrect, just "being cool".

Then try to use what you've learned rather than "being cool".

16. ### arfa branecall me arfValued Senior Member

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Nor have I.
It might be true, but I don't think there's any way to prove it is, even theoretically. Photons don't have frames of reference . . .
Would that mean it's an unprovable fact, but neither true or false; or is it unprovable and both true and false?

17. ### originTrump is the best argument against a democracy.Valued Senior Member

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First a projectile cannot move at the speed of light. So lets assume 2 projectiles are moving towards each other at 99% the speed of light. If you were sitting there watching this miraculous thing you would measure each of the projectiles speeds at 99%. The distance between the 2 objects would close at a rate of 198%c. The important point though, is no one would measure anything moving at >c. If you were even riding on one of the projectiles, when you passed the other projectile you would measure its speed to be less than c, NOT 198%c. That is the big point of special relativity, the speed of light in a vacuum (c) is constant and is the maximum speed in the universe, it is also independent of the observer. c is always c, no matter how fast the source or observer is moving. The other point is matter cannot attain a velocity of c.

That is what that equation that you couldn't understand was indicating. Einstein: 1, you: 0.

18. ### Janus58Valued Senior Member

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No, it's telling you that you can't use the simple addition rule for velocities.
To get the idea across, let's use another example. Say you are in the Northern hemisphere. You walk 2000 km South, then 2000 km West and then 2000 km North. Simple vector addition would put you 2000 km West of were you started. However, the surface of the Earth is curved, and the North-South lines converge a the poles. Thus assuming that you didn't cross the equator, you would end up less than 2000 km from where you started. The same is true is you walked 1 ft South, 1 ft West and 1 ft North; you would end up less than a foot from where you started. but at these small distances, the difference would be too small to notice or reasonably measure.

This happens because the curvature of the Earth changes the rules of how these individual distances traveled add up.

In Relativity, the fact that time and space are relative quanities and frame moving relative to each other measure them differently, does the same thing to the rules of adding velocities.
It's a consequence of the postulates of Relativity.

Everyone measures the speed of light as equaling the same value relative to themselves, and the laws of physics stay the same in all frames.

So let's say that you have a spaceship and it fires both a projectile and a beam of light from the tail to the nose. The light travels at c and the projectile at .9c. since the light travels faster, it gets to the nose first.

Now assume that this ship is flying past someone at .9c. To this person, the light travels also at c "relative to himself". Also, since the laws of physics must agree between ship and this person, he must also see the light reach the nose of the ship before the projectile does. But this means that instead of measuring the projectile traveling at 0.9c+0.9c = 1.8c, he has to measure it as traveling at less than c.

The formula given tells us just what speed he will measure it traveling at. It does this by taking into account all the Relativistic effects(Time dialtion, length contraction and the Relativity of Simultaneity).

19. ### CptBorkRobbing the Shalebridge CradleValued Senior Member

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It means velocities don't add the simple way one would intuitively think. If you're sitting on Earth and you see one rocket going one way at 75% lightspeed, and you see another rocket going the opposite direction at 75% lightspeed, you'd naively think they'll see each other going faster than light. In fact, because of the way space and time transform between different reference frames, the rockets will see each other moving faster than 75% lightspeed, but still slower than 100%. Linear velocity addition doesn't hold in Relativity. Now if you're going at a tiny, almost negligible fraction of lightspeed, even in a supersonic fighter jet, the Relativistic corrections to velocity addition are too sensitive to notice without special ultra-precision measuring devices, and you would still think velocities add in the intuitive sense. This effect was known in the mid 1800's even before Einstein came out with Relativity- see here for an example.

20. ### lambda orionisRegistered Member

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Just because Humanity cannot understand how to build a craft capable of going C doesnt mean its impossible, its just showing us that our brain is still working at 6% we are retarted, its that simple maybe when we evolve a little more we shall be a bit smarter there is a reason why we can only use 6% perhaps someone or something didnt want us getting far from home.

21. ### arfa branecall me arfValued Senior Member

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Look, Einstein was wrong, just ask anyone here.

You won't understand a word, but what's to understand? You think this stuff is easy?

22. ### KavanaughRegistered Member

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Er, that's a myth. There isn't a secret area of the brain that we'd be 10 times smarter if we could access it. :shrug:

23. ### phlogisticianBannedBanned

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Scifes, if you are cruising near C, everything in your spaceship looks normal. Relative to an observer however,... and the rest you have to go and look up.