Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum light speed

jjw004 wrote:
"Everbody knows that light speed will vary under circumstances wherein the light passes through some medium or other."

1. Not everyone knows it.
2. You told me I was incorrect now you tell me being correct is nitpicking.

You can't have it both ways. So what was the point of your first post?

a black hole emits no light, is this because the black holes gravity does not allow light to escape, or is it because the objects inside the black hole travel into the center so fast that the objects and its light is gone ...converted into energy and thats why we cant see it.

we can see the energy as it leaves the hole so
energy can escape.

(--> energy has no mass)

if this is the reason we see no light then the speed of light could not possibly be as most concieve it to be.

no, i was demonstraiting the point. two different observers see the things differently due to the effect the speed has. speed itself is not dependent on the frame of reference,

compaired to speed of light the stars are practically motionless.


the speed of light though a vaccuum is a constant, that makes it something that can be used as a frame of reference anywhere.


they time distance is constant, but your ability to observer it is diminished as time is compressed. on the other hand light moving away from you is not moving away as fast due to the fact that you are almost the same speed.

let me us a different analagy.

two observers see a train pass a crossing. the train blast the whistle as required.

one observer on the ground near the hears the whistle. as the train approaches the sound is higher due to the fact that sound travels though air at a given pressure and tempature at a constant speed. as the train passes the sound pitch drops. niether the pitch that was heard prior to or after the train passes are the same sound that the person in the train hears. if the train stops and whistles, it will make the same sound as the person in the train heard, but not either of the pitch heard by the one on the ground.

the person on a starship traveling just below the speed of light will have his time streached out as he approaches. the light leaving his ship will be moving away at a matter of a few miles per hour difference. (the speed of light will be the same, but the difference between it and the speed of the ship will be small). but since his ability to see the time in reference to the light, has been slowed, it will appear to be the same as normal.

to the outside observer, who is not moving realitive to light, will see the person in the ship compressed and motionless. he will also see that light is still moving the same speed, and will see the ship is just slightly less than light.

actually we see the energy that was almost captured by it, but escaped from just outside the event horizon.

dehammer wrote:
"actually we see the energy that was almost captured by it, but escaped from just outside the event horizon."

If we assume Steven Hawking and quantum mechanics are wrong.

actually that is if they are correct. the energy we see is from the event horizon. as things begin to accelerate and time begins to slow. matter is torn apart. that releases energy. that is what we see. once it gets beyound that point, it does not escape normally, only matter being shot out of the poles are coming from inside. and that is only visible if the pole is pointed at you.

I am sorry but I canot let this sentence from dehammer pass: i.e.

"if you go close to it, time slows down for you in comparison to the the person that it is not moving in relation to light. if he could see you, to him you would appear to be motionless. if you could see him, he would appear to be moving in a blur".

light is moving relative to all persons with a speed c; i.e. all persons are moving "in relation to light" (whatever this means) with a speed c". If a person moves relative to you with a speed approaching light speed, you will (according to his reference frame) move relative to him with a speed near light speed. There is no "blur". According to both observers the time of the other observer seems to be passing more slowly; however, within both frameworks the local time passes at the same rate the so-called proper time rate.

im afraid im having trouble with this.

if two ppl are moving at the same speed in relative to each other, they will see each other moving normal. they will be affect identically. to them, everything will appear to be normal. what will not seem to be moving normal is the things going slower in relation to light. these things will seem to be moving much faster. the slower the other things are moving in relation to light, the faster they will appear to the ppl moving at near light speed. to someone who is not moving in relation to light, will see them hardly moving. that is because time has not dialated for them (if that is the proper term, im not really sure - what else do you call it when time slows for you).

This where you violate the most basic postulate of relativity. To say "someone is not moving in relation to light" is the same as saying that light is stationary relative to this person. According to Einstein's postulates this can never be the case. Light will always move with a speed c relative to any person even when different persons are moving relative to each other they will each still measure a light speed c. This means that time becomes a coordinate which can be transformed from one reference frame to another. So if you transform the proper time within a reference frame moving relative to you into your reference frame, then YOU will experience the time to be slower than it is in the original reference frame from which you have transformed it. The time does not actually slow down in that reference frame. I hope this is of help.

totally wrong. i have no idea where you are coming claiming that if someone is stationary to light, light must be stationary to him.

perhaps you missunderstoon me. light is a constant.that make is something that can be used as a universal reference point. being stationary in relation to light mean that light is moving away from you at precisely light speed. someone at zero light speed is not moving at all.

if you are moving in relation to light then light moving in the same direction as you has slightly less speed in relation ship to you and light moving in the opposite direction is moving at slight faster that light speed in relation to you. this does not mean light is actually moving faster, because it cant. what is changed is its relation to you.

if light moved at relationship to the person, then the person in the ship moving .99 light speed moving at 1 away from him. while the person who was standing still would see it moving at 1.99 light. that does not make since. light moves at a constant. at does not move at a speed in relation to someone. the person in the ship would see it moving away from him at .01 times the speed of light, but due to time dialation (or compression which every the term is) it will seem to move away much faster.

if you slow down in relation to time you have to slow down in relation to everything else.

Oh I suspect JohnnyBoy understood you quite well.

You just wrote:
"perhaps you missunderstoon me. light is a constant.that make is something that can be used as a universal reference point. being stationary in relation to light mean that light is moving away from you at precisely light speed. someone at zero light speed is not moving at all."

Which clearly demonstrates that your score on understanding 20th century physics, well really 100 year old 20th century physics is a resounding zero. You just don't get even the most basic of Einstein's concepts.

It would be absolutely impossible for light to be moving away from you at anything other tan "precisely light speed."

Impossible.
Absolutely.
Totally.
Impossible.
There is no other choice.

Thank you DA.
The other postulate of Einstein that dehammer does not understand is that there is no universal reference point; all inertial reference frames, with whatever speeds they move relative to each other, are equivalent. If you transfer an observer from one to another and he cannot see the reference frame from which he came, he will conclude that he is stationary. If this were not the case, one would not have been able to walk from the back to the front in an aeroplane.

please explain this the person one is not moveing. person two is moving at .99 percent of light. light is moving away from the second person at light speed, so how fast is the SAME light moving away from person two.

light has only one speed. it cant move away from two ppl at two different speeds.

let me do this in another way.

person 1 is standing still. person 2 is moving away in a plane doing .99 mach (the speed of sound). how fast is the sound wave (from the plane traveling away from person 1) traveling in relation ship to person 1)

the answer for those who cant figure out simple physics is simple. sound travels at a given speed at a given air pressure at a given tempature no matter who is measuring it. the person 1 will measure the speed at the speed of sound. the person in the aircraft will measure it at the speed of sound. yet in relation to the jet, the sound wave is only traveling a small amount faster than he is.

the same is true of light. it has a given speed. einstein proved it. test since then have proved it. our understanding of the distance of object in space is based on this. if speed light changes depending on how fast the person or object generating it is moving, all of our understanding of the size of the universe, not to mention the placement of the stars, will have to be completely rewritten.

(note: for the sake of simplisty i use mach as being the exact speed of sound. aircraft mach numbers are actually just a little bit faster due to the fact that an aircraft traveling at precisely mach would soon have a lot of trouble due to the vibrations caused by traveling at that speed. i cant explain it that well, but being a veteran of the usaf, ive learn a few things concerning mach capable a/c)

light moves away at its speed. if your moving at a different speed, the difference in the speed and yours would not be precisely light speed. that has been proven.

have you ever heard of something called redshifting.

its a long time understood principle.

light has frequency. the color you see is a product of the precise frequency or combinations of frequency of the light that reaches your eyes.

when a object is moving towards you, since light cant speed up the wavefronts are compressed, causing the frequency to increase. this increase cause the light to appear to be reder than it would otherwise. simularly object moving away from you have the frequency of their wavefronts spread out causing the light to be blueshifted (appears to be more blue). this allows scientist to determine the approximate speed and direction of stars in relationship to the earth (or more precisely the observer). if light moving from a star that was approaching the earth moved at precisely the speed of light in relationship to the star, it would be moving faster in relationship to the earth and would therefore never redshift.

a simular situation occurs with train whistles. if you stand at a crossroad when the train blows it whistle, it will sound a certain way depending on its speed in relationship to you. if the train is motionless, it will sound the same as it does to the engineer. if the train is moving towards you the sound increases in pitch, sounding higher in scale than it does to the engineer. as the train moves away, the pitch drops, sounding lower than it does to the engineer. in light this is called redshifting and blue shifting. the speed of light in a vaccuum and the speed of sound at given pressure and tempature are both constant.

if your correct, einstein and all the other scientist are wrong. all the star maps nasa has made are wrong. all the understanding of the movements of the planets are wrong.

i am aware that ppl will see what they see no matter what. since you cant change the placement of your center of awareness, (at least most ppl cant) your not going to see anything from any different perspective than that. the car moving 120 miles an hour will be moving towards you weither its moving along the road or is parked and your falling (at least until impact then everything changes).

i am also aware that there is no "universal refernce point". but you can specify something as a reference point and the speed of light is a good one since it has a constant speed. in any converstation there has to be a reference point or there cant be any understanding.

how much understanding would there be if you were talking with a red shoe as a reference point and the next guy was talking about blue fish. a discussiong of apples and oranges would be with a reference point of fruit, not apples or oranges. otherwise there is no understanding.

Yes, that's right. It is the case, however, that if you assume Coulomb's law and special relativity, then you can derive all of the Mawxwell equations. You don't have to postulate a magnetic field, Faraday's laws etc. It can all be derived mathematically.

The speed of light is 1 in natural units. In theoretical physics it is customary not to distinguish between space and time and to use the same units for both. In high school, physics students are often wrongly taught that Length, Time and Mass are incompatible.

dehammer asks:
"please explain this the person one is not moveing. person two is moving at .99 percent of light. light is moving away from the second person at light speed, so how fast is the SAME light moving away from person two."

At light speed.

Both obsevers measuring the speed of light will measure the exact same value.

I believe that we are all arguing at cross purposes here. Dehammer has a point when the firts observer measures light speed and the speed of the second obserrver relative to the inertial reference frame of the first observer. He will then see that the second observer catches up partially with the light moving away from the second observer; i.e. the light moves away at the speed c-v where v is the speed of the second observer. If this were not so there would not have been a Doppler shift for light; however, the second observer will still observe the light moving away from him as moving with a speed c relative to his own reference frame. In special relativity it is of utmost importance to carefully specify the reference frame relative to which an observation is being made. It is for this reason why two observers moving relative to each other can differ on whether two events are simultaneous. If it is simultaeous in one reference frame it is not so in the other.

the speed of light will be measured by both to be the same, but the one that is moving at nearly the same speed will, if he can overcome the time dialation problem, that the light is only a small amount faster than him. if he cant over come it. the fact that he has slowed down so much will make it appear to him to still be moveing the same speed. this is because he will be moving only 1/386000 as fast as the guy that is not moving in relation to light.

JohnnyBoy wrote:
"He will then see that the second observer catches up partially with the light moving away from the second observer;"

dehammer has no point. He doesn't understand elementary school level relativity.

He points out the issue rather clearly, above, when he says "if he can overcome the time dilation problem."

When pigs sprout wings and fly.

Time dilation isn't a problem to overcome ... it is the law.

at our lvl of understanding its does appear to be unavoidable. but then again. it was less than 1.25 centuries ago that "man could not fly" was considered a law too. there might be a way of overcomeing it that we havent the slightest clue about. by the same tolken getting to .99 c is at this time beyound our capacity too. Its a "law" that it would take infinite energy to reach that point. therefore if you total arguement is based on what is the "law", why are you even bothering to post. if time dialation slows your perception to 1/7 that of an outsider, and you are traveling at 6/7 the speed of light, light will seem to be moving at precisely the same speed. but since you will mass 7 times that of what you were originally how would you get to that speed anyway.

we are not discussing things that are possible now.

you do seem to be trying to wrestle me into the reverse of what i was originally saying but im not. if your doing some political game of pushing ppl into the opposite arguement, look else where.

as i have said, light speed is the same no matter what speed you are doing.

time dilation can make the difference between what speed you are going and the speed of light seem to be the same as it would appear to a outsider observer. this is my original point and what im saying all alone.

argue what you want, the speed of light leaving the second person is no faster or slower than the speed of light leaving the person in the ship.