Einstein was wrong, the speed of light cannot be constant because it's immeasurable by his own theo

reply to post by Astyanax


"to take what scientific experts tell us on faith"

sounds like a cult,,of high Priests

QUESTION EVERYTHING!

reply to post by muzzleflash


the whole premise is that the speed of light through a vacuum is constant. i hadn't seen that experiment, and it is truly fascinating, but as light has no mass, this doesn't violate einstein's theory.

almost reminiscent of tachyons.

Originally posted by BobAthome
"to take what scientific experts tell us on faith"

sounds like a cult,,of high Priests

QUESTION EVERYTHING!

A little out of context maybe?

The point was if you don't personally have direct experience with the material then it's understandable that you would doubt or disbelieve. A reason but not an excuse though, as you can "question everything" concerning science do to the ability to falsify or repeat experiments.

reply to post by dyllels

No. A frame of reference is static to an observer stationary within it, however fast that observer may be moving in somebody else’s frame of reference.

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reply to post by mobiusmale

If I shot a beam of light into a vacuum, it would travel at the maximum theoretical (or absolute) speed. If the beam then entered, say, a clear glass of water, it would slow down to whatever speed light likes to travel in water. On the other side of the glass, is a vacuum again.

My first question is, after the light emerges from the glass, at what speed will it want to travel. Will it continue along at the speed it was going while it was in the water...or will it accelerate up to its maximum speed again? If it speeds up again, by what process can it do so? Wouldn't this go against the principle of momentum...that things will tend to continue on their way at a constant speed unless acted upon by a force of some kind?

Very intelligent question.

The answer is that it would speed up again. This does not violate Newton’s first law of motion. The law only applies to massive objects and photons are massless.

The photon would certainly lose ‘momentum’, that is to say, energy. The result of this would be a reduction in the frequency of the light – it would change colour, so to speak.

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reply to post by muzzleflash

Of course the speed of light isn't constant. How do you think it get's sucked into a black hole? It has to change it's speed flying outwards and turn inwards.

That is not what happens. The light, always travelling at the same speed, follows the curvature of space around the black hole. Gravity makes sure the light never gets beyond the event horizon of the hole, but those photons are still whizzing round and round it at c.

Light travels as if it is on rails. Gravity shapes the landscape over which the rails run. When the track bends, the train follows the track.

To repeat what I said in an earlier post: relativity is hard. You have to understand the concepts, then you have to understand the mathematics, then go back to the concepts and see what the mathematics implies for them. It isn’t for everybody. It certainly wouldn’t have been for me, except that I sat down in lecture theatres and had it explained to me by experts, then went off to the lab and did the experiments. And believe me, it was bloody hard.

I don’t believe you can expect to understand relativity without such a course of academic study. Self-study won’t do it; you need to be taught. That’s because there are too many ways to get your ideas wrong and go off at a tangent – sometimes literally, as in this poster’s case.

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reply to post by BobAthome

sounds like a cult, of high Priests

From your perspective, it certainly does. And you are certainly well within your rights to question it.

Just make sure you know enough to understand the answers.

reply to post by underspace


but alas,it turned out
the world was not flat
that it hangs in space
the galaxie is not set in perfection
the speed of light is not constant
when you change its point of reference.

when a photon of light,, a wave,,
travels through a constant, resistence
its speed is determened by this resistance,
etccc.
when this photon is in a point of reference,
where there is absolute vacumn,
does the speed of light,
change.
that is the question, as i understand it.

"Einstein was wrong, the speed of light cannot be constant because it's immeasurable"

cannot be constant because it's immeasurable
in a different point of reference, outside of a vacumn and an atmosphere,
sure i guess its possible.
but first establish your point of reference,
vacumn and atmoshere are real points of reference,
as well as sub atomic,
well except for , strangelets. and strings, and black holes, and anti-matter,,??
lol see?


by the energy used in
overcomming this resistance or loss of energy

etc,,,,

reply to post by BobAthome


I am currently in the position that I take science as faith as explained by Muzzleflash.

So no, I don't see, nor do I understand the questions.

However, it seems many intelligent people in this thread are saying that the speed of light is indeed constant, and you are saying it's not, and I am curious about that discrepancy. Curiosity IS something I can stand on with a position of authority

Originally posted by Helious

Originally posted by AnnoyingOrangeX

Originally posted by BIGPoJo
If you are moving at 20mph light coming from you will still be traveling at 186mps no matter where the light is observed. If you throw a ball at 6mph out of car at 20mph you could say that the ball is moving at 26mph. Balls thrown from moving vehicles follow different rules than light. You cannot add the 20mph to the 186mps because it is already going at max speed.

no ...you are assuming that it travels at max speed and therefore behave other than the ball because this is implied by what einstein said but this is actualy not the case. Why should light behave otherwise than anything else?

Because light is made of photons and photons do not have mass, unlike a baseball, or as you put it, "anything else". That being said, we already know it is not an absolute constant because we know black holes exist. Light traveling outwards from the center of a star is also slowed down. Einstein knew both of these things and his work actually predicted it before it was proven.

I'm sure this has already been corrected, but, photons do have mass. Light is a form of matter with such small mass that it can behave both like a wave and as a particle.

Light speed is not constant, it only seems constant to the observer because wherever the observer is the speed is affected the same way. The calculation of the speed of light is an ideal environment formula, meaning that in the theoretical complete vacuum of space light would move at this speed. Light is pushed and pulled by gravity in the same way as any other particle, if this was not true then light would not be captured by a black hole or bent around a star as it passes. This was proven by scientists observing a total solar eclipse, like a pencil in a glass of water, the stars behind the sun that have light pass closely around the sun appear to be in a slightly different place than they really are. Thus proving that light is affected by gravity and therefore cannot he constant.

Originally posted by libertytoall
Basic logic tells me light speed would have to be infinite in order for it to remain constant for an observer regardless of motion or at rest, in relation to the source.

Remember e=mc^2? If the c is infinite, then the annihilation of even one particle would release an infinite amount of energy. But we annihilate particles all the time; not one of these reactions has produced an infinite amount of energy. Therefore, c is finite.

e=mc^2 is also the same reason c can't have different values at different points in time or different places in the universe. Varying the energy=mass equation throughout the universe would result in different nuclear reactions being possible. We'd be able to look at stars and see that they weren't burning the way we expect them to.

reply to post by DarkSarcasm


No, that hasn't been corrected, because what you said is incorrect.
The speed of light is constant...as "I" (and others, though less succinctly) have already showed. In all reference frames, by all observers, in all instances, at all times, everywhere, the speed of light is always measured to be the same precise value.
Light is only affected by gravity because gravity warps spacetime, and light follows a straight path through spacetime. Black holes warps spacetime so much that the "straight path" through this spacetime actually appears to us to be a circle.

Also, light has zero rest mass. At speed, however, light gains not mass (not even a really small amount of mass), but momentum (p = hf/c). This is because of mass-energy equivalence, and is one of the two forces behind the concept of solar sails.

Originally posted by Seektruthalways1
reply to post by libertytoall

 

LOL yup he was wrong, light isnt a constant.

abcnews.go.com...

scienceblog.com...

"Slowing" the speed of light is a very layman term. It doesn't actually involve slowing the speed of the photons, as that would violate the very necessary constancy of the speed of light. What it does involve, however, is the speed at which those photons are transferred (note, not the speed at which they travel, but the speed at which they are transferred) through a material. These transference speeds can be very slow, but they do nothing to the speed of the photons, which is always the same value.

Originally posted by Astyanax

I don’t believe you can expect to understand relativity without such a course of academic study. Self-study won’t do it; you need to be taught. That’s because there are too many ways to get your ideas wrong and go off at a tangent – sometimes literally, as in this poster’s case.

I would be a perfect exception to that rule. But okay.

Originally posted by CLPrime
(note, not the speed at which they travel, but the speed at which they are transferred) through a material. These transference speeds can be very slow, but they do nothing to the speed of the photons, which is always the same value.

For my limited inquiring mind, can you in laymen terms explain and differentiate 'travel speed' and 'transference'?

reply to post by underspace


The full explanation is a little more complicated than this (look up phonons sometime), which is why I was trying to avoid it, but here's how I usually explain it:

When light passes through a medium that's not a vacuum, the photons encounter electrons in the medium. These electrons absorb the photons, and are excited to a higher energy level. Then, those photons jump back down to their original energy level, and, in the process, emit a photon. It would then be the speed of absorption/re-emission that determines how fast photons are transferred through a medium/material. If the electrons are slow at this process, then the measured speed of light through the material will be slower than the speed of light, even though the photons, themselves, never travel any slower than the speed of light.

with my limited understanding of physics,

speed of light is always at c in a vacuum whether you are moving or at rest. You shoot laser from a space ship which is traving at half the speed of light, the laser beam will still be observed as going at c. if you are at rest in space and shoot a laser, it will still be observed as speed of c.

so i donno what you are saying

Originally posted by Seektruthalways1
reply to post by libertytoall

 

LOL yup he was wrong, light isn't a constant.

abcnews.go.com...

scienceblog.com...

A little good natured heads up if I may...

The speed of light when detonated as C specifically references the speed that an electromagnetic wave propagates in a vacuum

The speed at which light propagates through transparent materials, such as glass or air, is less than C.

While there are certain situations where matter or energy appear to travel at superluminal velocities from the perspective of the observer but in reality C is never exceeded ( remember, C is the speed of light in a vacuum )

If you were to have read and understood the two articles you sourced in your post you would note that the first titled Scientists Slow Down Speed of Light specifically states ...

The experiment doesn’t invent any new physics.When light passes through a material such as water or glass, it slows down a bit as the photons interact with the surrounding molecules. The new result merely set the world record for slowest light.

The second article with the sensational title Light that travels faster than the speed of light goes on to describe a new technique to economically moderate light propogation by using off-the-shelf instrumentation in normal environmental conditions and specifically states that...

This is not the first time that scientists have tweaked the speed of a light signal. Even light passing through a window or water is slowed down a fraction as it travels through the medium. In fact, in the right conditions, scientists have been able to slow light down to the speed of a bicycle, or even stop it altogether.

and specifically regarding a perceived violation of special relativity...

And even though this seems to violate all sorts of cherished physical assumptions, Einstein needn't move over – relativity isn't called into question , because only a portion of the signal is affected

To paraphrase for anyone still scratching their head over this... "LOL nope he (Einstein) was right, the speed of light ( C ) is a constant."

I hope this helps.

Now what exactly is light? A Scottish physicist named James Clerk Maxwell (1831 - 1879) showed that electric and magnetic fields fluctuating together can form a propagating wave, which was named an electromagnetic wave. Light is this type of wave. Maxwell knew that a changing electric field produced a magnetic field. He hypothesized that a changing magnetic field would produce an electric field because most things in nature are balanced. Based on the work of Farady and Hertz, this was discovered this to be true. A common way to generate an electromagnetic wave is to have an antenna connected to an alternating current which will cause a changing magnetic field which will cause a changing electric field which will cause another changing magnetic field and so on. These waves are also produced in stars in the form of UV rays, X rays and Gamma rays.

An electromagnetic wave, like other waves, has a frequency f, a speed v and a wavelength lambda, which are related by the equation . In vacuum or in air, to a good approximation, the speed v = c (speed of light: 3 x 10 to the 8 m/s) so the relationship would be v= f lambda

library.thinkquest.org...

have they yet to agree on the very nature of light? (particle vs wave)


speed is defined as distance divuided by time

in order to measure a speed, you need a set distance and record the travling time of the object of interest

thus speed is a lineal measurement and is not affected by relativity as it is assumed to be constant across the measured distance

velocity, on the other hand, is not 'speed' and in physics is not assumed to be constant across the distance bit only in the point of time measured, and therefore is affected by relative motion in its absolute purest form
hence the equation (velocity) V=u+at for an object inituially at rest, and the equation V2 = U2 + 2as where V is the measured 'end' velocity and U is the 'initial' velocity

so what do you do as a good physicist? Scope your observations in terms of the controlled environment that is effective only for your observations assumptions, and resulting theories

somewhere, someone has "100% undeniable proof"

reply to post by 31Bravo


he is right i watched something about the speed of light
and they used what he said in that programme
speed 186,000mps but you can slow speed down in
some form of liquid that to was shown to
i think the mans name in said documentry
was a mr tyson (and no not iron mike tyson)

reply to post by libertytoall

well tell that to nasa who send a lazer beam of light to the moon and back
everyday to measure how far it is moving away from us which is about
3cm (gone blank on whether its a day or a week or a year)
im sure someone will tell us

Originally posted by DarkSarcasm

I'm sure this has already been corrected, but, photons do have mass. Light is a form of matter with such small mass that it can behave both like a wave and as a particle.

Light speed is not constant, it only seems constant to the observer because wherever the observer is the speed is affected the same way. The calculation of the speed of light is an ideal environment formula, meaning that in the theoretical complete vacuum of space light would move at this speed. Light is pushed and pulled by gravity in the same way as any other particle, if this was not true then light would not be captured by a black hole or bent around a star as it passes. This was proven by scientists observing a total solar eclipse, like a pencil in a glass of water, the stars behind the sun that have light pass closely around the sun appear to be in a slightly different place than they really are. Thus proving that light is affected by gravity and therefore cannot he constant.

Mass bends space and it is the bending of space that affects the path the photons take. Photons do no not bend space since they have no mass.

You are getting confused between gravity (due to mass) affecting space curvature and the affect of space curvature on things moving through it. The scientists you mention merely proved that space was curved ie they proved Einstein was correct.

its a theory. many theories cant be tested doesnt mean they are wrong, doesnt mean they are right either, they are just theories

and IF he did get it wrong, that doesnt mean he was covering anything up.