Aces High Bulletin Board
General Forums => The O' Club => Topic started by: Hortlund on January 08, 2004, 08:08:57 AM
-
I'm sure you all remember this from high-school physics, but if you sit in a car that travels at 25 m/s and fires a gun forward, and the speed of the bullet is 300 m/s, then the speed of the bullet will be 325 m/s. And if you turn around and fire it backwards, the speed will be 275 m/s. The same is not true of the speed of light, because the speed of light is constant irregardless of the relative movement of the observing or moving body. That is what I mean when I say that the speed of light is a constant.
Take the sun as an example, it revolves around the center of our galaxy at a modest 217 000 m/s. A photon, or ray of light if you will, that leaves the "front of the sun" (i e in the direction of movement) will have the speed 299 792 458 m/s, and not (as one might expect from the car example) 299 792 458 + 217 000. Meanwhile a photon leaving the back of the sun will ALSO have a speed of 299 792 458 m/s and not 299 792 458 - 217 000.
I dunno if there are any physics nerds here who can tell me if we have found an explanation to this, because me being a law-nerd really have no idea, and back when I was in school, no one had the answer to that question.
-
What's the question?
-
Why is the speed of light a constant, or an absolute. Doesnt that ...defy the laws of...something (see car/bullet analogy).
And how can light be both a wave-movement AND a particle (at least according to my old physics teacher). Something about a proton having a mass while travelling at the speed of light, but not having any mass if not travelling at that speed.
-
Originally posted by Hortlund
I'm sure you all remember this from high-school physics, but if you sit in a car that travels at 25 m/s and fires a gun forward, and the speed of the bullet is 300 m/s, then the speed of the bullet will be 325 m/s. And if you turn around and fire it backwards, the speed will be 275 m/s. The same is not true of the speed of light, because the speed of light is constant irregardless of the relative movement of the observing or moving body. That is what I mean when I say that the speed of light is a constant.
Actually it's not true that the speed of light is constant - it can be changed by gravity - at leasts it's relative speed.
And measuring Speed depends upon relativity and where you observe the object you are trying to measure ;)
What exactly is your physics questions...
-
I thought the speed was the same, but you get a blueshift redshift thing with gravity and stars, depending on what direction from the sun they are travelling, and depeding on gravitational influence.
-
Originally posted by Hortlund
Why is the speed of light a constant, or an absolute. Doesnt that ...defy the laws of...something (see car/bullet analogy).
And how can light be both a wave-movement AND a particle (at least according to my old physics teacher). Something about a proton having a mass while travelling at the speed of light, but not having any mass if not travelling at that speed.
Its not so much as thinking of light having a constant speed, (recently disproven by an Australian scientist) but in your relation to seeing said light..
Light waves like any other traveling wave still is subject to the doppler effect. Take for example the theroy of the expanding universe. They believe the universe to be expanding because the far out stars all seem to have a 'red' shift. Meaning they tend to have a more red hue because they are traveling away from us. An object with light traveling towards us appears to have a 'blue' (i think) shift.
Proven recently though, light is very much subject to the universal power of gravity. Gravity effects the speed of light in direct proportion. Gravity can also bend light, skew light, and change every aspect of light that can be seen...
But in the end... Every type measurement given or taken was done from a particular relation.. Light can be said to have a constant speed, but I believe that to be just the 'normal' speed if you will... It can be changed or affected...
As far as light being a partical and a wave.. Thats a little deep for me here and now... Steven Hawkin's book, A Brief Moment in Time, has a few chapters that will cover this. But still, it is pretty hard to grasp..
-
Originally posted by kappa
Its not so much as thinking of light having a constant speed, (recently disproven by an Australian scientist) but in your relation to seeing said light..
Isnt that the experiment where they shot a laser light through some atoms who were frozen to -270 or something and found out that the light waves came out on the other side a fraction of a second faster than they would have if they had been travelling through a vaccum?
-
Originally posted by Hortlund
Isnt that the experiment where they shot a laser light through some atoms who were frozen to -270 or something and found out that the light waves came out on the other side a fraction of a second faster than they would have if they had been travelling through a vaccum?
Actually I'm not sure how they did it.. Or what the results were.. Just the answer seemed to be that gravity infact can account for different light speeds. This experiment gives the idea that light could be 'controlled' by gravity.. Perhaps even the other way around as well.. Who knows..
As far as the vaccum goes, I dont know about that either.. Light waves and sound waves tend to have very different properties.. I'm not sure if a vaccum would have any effect on the speed of light as space itself is a vaccum.. But im no physisist.. hehe
But to add again.. Speed is only a figure that matters in relation to that or those that measure it.. Its all about were you are and whats going on around you.. Your relation to said event..
-
As nakhui already pointed, speed is relative to the point of observation.
If you live on the bullet (or are the bullet itself), you will notice the rest of the world suddenly acelerating around you to different speeds.
And, more, there's something weird happening when you come close to the light speed, as those simple equations show (for God's sake, simple for Einstein, not for me!!! :mad: ).
In fact as a basic effect of the close-to-light-speed the mass of the object observed will tend to reach an infinitive mass value, deforming the space (as the gravity rules said), and then changing the light speed constant and time itself...
A complete mess!!!
:)
As for the second part of your question, a proton have always a mass, even a photon have a mass, the only particle where doubt is remaining about mass presence is the neutrin.
The weird thing (again) is that as you go close to lightspeed the mass will tend to become infinite, (IIRC the change become sensitive above 10% of light speed), so a proton will have a variable mass, but will always have a mass.
The basic problem IMHO is that, being the observer always relative, how the lightspeed can be an absolute??
No clues.
Is that your question???
Ask Stephen Hawkins.
Well maybe he will start with the event horizont, and speed of information, bringing a new level of confusion in your ideas, untill you decide to stop thinking, and go back playing AH. ;)
.....
Ehmm...
What I was talking about?? :confused:
(note to himself: stop drinking wine during lunch... hic!)
:)
-
I've got a masters degree in physics, but I hate lawyers so won't tell you.
But seriously, special relativity is a pain to understand at first, but once you get it you'll wonder what's the big deal. General relativity, now there was something I detested. Anyway, we were recommended a children's book on the subject back in the first year which was really very useful. It's in layman's terms (can't remember if it has any equations in it). I'll try and track it down for you.
-
Unified theory of Classical Quantum dynamics, pt1 (http://www.blacklightpower.com/pdf/GUT/TOE%2002.10.03/Parts/Part%20One%20(Intro-Chapter26).pdf)
Unified theory of Classical Quantum dynamics, pt2 (http://www.blacklightpower.com/pdf/GUT/TOE%2002.10.03/Parts/Part%20Two%20(Chapter%2027-40).pdf)
-
maybe you should stick to playing with curved mirrors...much less confusing and a lot more fun...
-
The speed of light is constant. But the "why" of it goes beyond most individuals ablity to explain or understand. This includes me.
Do a web seach like Moot did and start reading. Report back in 30 days......
-
It is confusing. Consider this.
A photon leaves the sun in one direction traveling 300k km/s while at the same time another photon leaves in the opposite direction traveling at the same speed.
From the sun's perspective after one second both photons will be 300,000 km away but in opposite directions. It would seem logical to assume that from the perspective of either photon the distance to the other photon is at this point 600,000 km and therefore travel time away from the other has been perceived as two seconds since light speed is considered to be absolute.
However, since the photons travel at light speed no time has passed. Furthemore, no time will ever pass for the photon as it travels indefinitely throughout the Universe from our perspective.
BTW, someone recommended "The Elegant Universe" by Brian Greene a while back and I have found it to be very interesting.
-
Seeing light as blue or red is not related to "the speed of light" but the wavelength of the light.
I've not heard of gravity effectively slowing light. I have heard of it bending the light's path... but not slowing it.
MiniD
-
Originally posted by Mini D
Seeing light as blue or red is not related to "the speed of light" but the wavelength of the light.
I've not heard of gravity effectively slowing light. I have heard of it bending the light's path... but not slowing it.
MiniD
yes, color shifts are frequency related...
It was just with in the last 2 years that a Australian physisit (i think) proved that gravity effected the speed of light.. That light did 'not' have a constant speed...
-
Take the sun as an example, it revolves around the center of our galaxy at a modest 217 000 m/s. A photon, or ray of light if you will, that leaves the "front of the sun" (i e in the direction of movement) will have the speed 299 792 458 m/s, and not (as one might expect from the car example) 299 792 458 + 217 000. Meanwhile a photon leaving the back of the sun will ALSO have a speed of 299 792 458 m/s and not 299 792 458 - 217 000.
1. the sun isnt in the center of the galaxy...its somewhere on one of the "arms"
2. "back of the sun" doesnt really count because its on the other side...the light leaving it travels away from the earth...
3. the "front of the sun" light that we can see all travels at the same speed but i beleive the frequency changes due to the doppler effect (and thus multi coloured light)(dont know if this is true...but it seems to make sense to me right now...please correct me if im way off on this)
-
Gravity is considered by most to be the curving of space. Light passing through strong gravity takes longer to go from point a to b because it is traveling further, not because it's speed has changed.
-
The effect of gravity on light was to make it appear to change it's speed - what was in fact happening was a deviation in path, effectively making it 'slow down' due to an increase in distance travelled. In fact there was no decrease in speed.
That book was called 'Uncle Albert' something or something according to 'Uncle Albert'.
Also, the most important thing to remember is that everything is relative to the point of observation.
-
Originally posted by Dowding
The effect of gravity on light was to make it appear to change it's speed - what was in fact happening was a deviation in path, effectively making it 'slow down' due to an increase in distance travelled. In fact there was no decrease in speed.
That book was called 'Uncle Albert' something or something according to 'Uncle Albert'.
Also, the most important thing to remember is that everything is relative to the point of observation.
that is true but not entirely...... Gravity bending light was proven many many years ago during an eclipse of the Sun.. I cant remember what star it was they used, but it seemed to shift locations caused by the Sun's gravity...
I will find info on gravity 'changing' the speed of light.. it does happen and has been proven.... Dowding, you have a masters in physics and have read nothing of this? It was farly recent.......
Besides, if it couldnt, why cant light escape a black hole.. 8)
-
Originally posted by AKIron
Gravity is considered by most to be the curving of space. Light passing through strong gravity takes longer to go from point a to b because it is traveling further, not because it's speed has changed.
You're information is a little out of data, sir.
Here's a few articles about what has recently been discovered about the speed of light.
http://www.cbsnews.com/stories/2002/08/07/tech/main517850.shtml
http://www.abc.net.au/lateline/s347215.htm
http://www.space.com/scienceastronomy/generalscience/constant_changing_010815.html
http://www.icr.org/pubs/imp/imp-179.htm
You know since I went through school.... there's been at least 4 new elements discoverd (or should I say created... but we knew in theory where they belonged in the periodic chart)
Another interesting principle of science - "Knowledge is not constant."
What you learned yesterday isn't necessarily true today.
-
Well, not exactly how I remembered it.. But relative..
http://msnbc.msn.com/id/3077354/
http://abc.net.au/news/indepth/featureitems/light.htm
-
Besides, if it couldnt, why cant light escape a black hole.. 8)
go to a soft mattress and put a heavy weight on it...roll a marble past the depression caused by the weight...
light cant escape the black hole because its not going fast enough to "swing" down the "steep slope"of the gravity well and "swing" back out...it hits the "steep" part and merely falls...
-
Originally posted by Nakhui
You're information is a little out of data, sir.
Here's a few articles about what has recently been discovered about the speed of light.
http://www.cbsnews.com/stories/2002/08/07/tech/main517850.shtml
http://www.abc.net.au/lateline/s347215.htm
http://www.space.com/scienceastronomy/generalscience/constant_changing_010815.html
http://www.icr.org/pubs/imp/imp-179.htm
You know since I went through school.... there's been at least 4 new elements discoverd (or should I say created... but we knew in theory where they belonged in the periodic chart)
Another interesting principle of science - "Knowledge is not constant."
What you learned yesterday isn't necessarily true today.
Wow, interesting stuff. The last article speculates the rate of decay in the speed of light to be 38km/s per year. They further speculate that this may be as a result of change in the additional quantum level dimensions which make up space.
Way over my head but if these analysis are correct then it would seem that space and time are changing. If so, it may not be light that is changing but rather the medium in which it exists and is observed from.
-
Originally posted by vorticon
go to a soft mattress and put a heavy weight on it...roll a marble past the depression caused by the weight...
light cant escape the black hole because its not going fast enough to "swing" down the "steep slope"of the gravity well and "swing" back out...it hits the "steep" part and merely falls...
Nice analogy.
-
My degree is three and a half years old. I have avoided physics like the plague ever since - after 4 years I had had enough and went to work doing something completely unrelated. Actually, I haven't had anything to do with relativity for 5 and a half years, since after the second year I chose modules that concerned the semi-conductor industry; that being the area I was most interested in.
I'll scan my degree certificates if you still doubt I hold the qualification and I can email you my thesis on the photo-electric properties of poly-pyridine. ;)
-
Someone with a good memory of advanced physics should read what the guy I linked says, because he's basically refuting Einstein and Feynman (and Greene) etc.
-
Is the speed of light different in vaccum, water or air? Or is it the same irregardless of in what medium?
-
The speed of light can be increased or decreased depending on applied variables.
I know this because there is nothing in the cosmos that is perfectly constant forever. Except the single creating force of all that is nature (aka GOD).
-
Hortland, it's the same everywhere. Think of the SOL as a type of boundry between the 'present' and the 'past'. One reason matter(you) can't go faster than the SOL is because if you did it would take you into the past (a big No-no). You are a three dimensional being that is moving at the SOL though Time. If you could out run that movement you wouldn't go into the future (it dosen't exist yet) but you would catch up with a past 'present'.
My little theory and a dime will get you a ride downtown on the bus so take it at face value:p
-
Originally posted by Otto
Hortland, it's the same everywhere. Think of the SOL as a type of boundry between the 'present' and the 'past'. One reason matter(you) can't go faster than the SOL is because if you did it would take you into the past (a big No-no). You are a three dimensional being that is moving at the SOL though Time. If you could out run that movement you wouldn't go into the future (it dosen't exist yet) but back to into the past.
My little theory and a dime will get you a ride downtown on the bus so take it at face value:p
I've actually be able to prove this theory....
by traveling very very very fast... turning around so my butt faces forward and then farting... the combined velocity causes my farts to go into the past....
and next thing you know everything is backazzward :p
-
Originally posted by Hortlund
Is the speed of light different in vaccum, water or air? Or is it the same irregardless of in what medium?
Do a lookup on Cherenkov Radiation. Light can slow down, and particles can travel faster than light.
ra
-
Nakhui,
I sure STEPHEN HAWKING will be in touch and you'll be ask to lecture at Cambridge, with the understanding that no open flames will be allowed
-
Originally posted by Hortlund
I'm sure you all remember this from high-school physics, but if you sit in a car that travels at 25 m/s and fires a gun forward, and the speed of the bullet is 300 m/s, then the speed of the bullet will be 325 m/s. And if you turn around and fire it backwards, the speed will be 275 m/s. The same is not true of the speed of light, because the speed of light is constant irregardless of the relative movement of the observing or moving body. That is what I mean when I say that the speed of light is a constant.
Take the sun as an example, it revolves around the center of our galaxy at a modest 217 000 m/s. A photon, or ray of light if you will, that leaves the "front of the sun" (i e in the direction of movement) will have the speed 299 792 458 m/s, and not (as one might expect from the car example) 299 792 458 + 217 000. Meanwhile a photon leaving the back of the sun will ALSO have a speed of 299 792 458 m/s and not 299 792 458 - 217 000.
I dunno if there are any physics nerds here who can tell me if we have found an explanation to this, because me being a law-nerd really have no idea, and back when I was in school, no one had the answer to that question.
The correct formula for adding velocities is not
V = u + w
... but ...
V = (u + w) / (1 + u*w/(c^2))
This is true for fast photons as well as for slow cars and bullets. It is just that when u and/or w are small, the denominator is very close to a 1, and the formula "simplifies" to
V = u + w
Since most of the velocities we dealt with until XIX century were very small in comparison with c, no one has noticed that V = u + w is not correct. The approximation is very close.
If one of the velocities you are trying to add is a c (u = c), the formula reduces to
V = (c + w) / (1 + c*w/(c^2)) = (c + w)/(1+ c*w/c^2)) = (c + w)/(1+w/c) = (c+w)*c/(c+w) = c
regardless of what w is.
Speed of light
Think about it this way. There is an absolute speed limit and it is exactly the same in all (not accelerating) frames of reference . Since all frames of reference are equivalent (a principle of special relativity), it follows that the max achievable speed should be the same in all of them. If it weren't you would be able to tell the difference between them and single out certain "special" frames of reference, which would violate the principle of the theory.
This speed limit is denoted as c.
Now, it just happens that photon in a vaccuum travel with the maximum achivable speed (c). As an unfortunate result physicists "equated" the two. This resulted in a very popular (but incorrect) statement:
"Speed of light is the maximum speed possible."
The statement above is false. What is true, is:
"The light travels (under certain conditions) at the maximum achievable speed c."
-
Its been years since I've looked into Physics but my own interpretation was that as matter reaches the speed of light, its mass will increase. There is a limit for the mass of matter in our universe (sorry for bad wording). Beyond the speed of light, matter converts into energy. Thats if you can get anything to go beyond the speed of light. Im no expert on the matter. This is just my own understanding of it.
-
Here you go.
http://www.physlink.com/Education/AskExperts/ae388.cfm
-
Originally posted by mietla
"Speed of light is the maximum speed possible."
The statement above is false. What is true, is:
"The light travels (under certain conditions) at the maximum achievable speed c."
Thanks for the reply mietla. I understand everything (hah.. right!) up to this point.
The way I understand that last sentence is:
"light travels at the speed of light" ...which really looks like a tautology in my book.
-
Very interesting thread (and I understand it better as sober ;) ).
Hortlund, re-read Mietla's answer.
"c" is not lightspeed, is the constant (apparently) "maximum speed limit" of the universe, according to this, nothing in the universe can exceed this limit (can you imagine the speed limit ticket you'll got?? :eek: ;) ).
It happens that the photon is one of the few particles that can reach, generally, this speed limit, so in popular culture (mine, since 5 minutes and a BBS thread ago) "c" is equated to lightspeed.
The correct statement is:
Lightspeed is generally equal to universe's maximum speed "c".
-
Some Physics experts don't belive in the absolutness of the light speed. And as a matter of fact, danish scientists managed to "slow" down light to the stunning speed of only 100 km/h if my memory serves me right.
There are many things in the universe unexplained, including the big ones as "what is gravity". REALLY!!
-
Originally posted by Hortlund
....if you sit in a car that travels at 25 m/s and fires a gun forward, and the speed of the bullet is 300 m/s, then the speed of the bullet will be 325 m/s. And if you turn around and fire it....
Einstein started to think about this and then asked the question how do you know the car is doing 25 m/s? 25 m/s in relation to the side of the road, but how fast is the road moving, how fast is the Sun orbiting, and how fast is the galaxy moving, etc...
Your perception of velocity depends upon your frame of reference. As long as the car is at a constant velocity, all the newtonian phenomena work within the car as though the outside of the car does not exist.
So one could, by his observances in a closed non accellerating room, validly say he was at rest and all other things are moving in relation to that room.
These thoughts culminated in the idea that there is no universal gridwork from which all is measured. Gridworks could be started anywhere, and all would be equally valid.
About that time, experiments were undertaken where the speed of light from distant stars was measured when the orbit of the earth was moving toward the star and again in six months, when at the opposite point of the orbit.
These experiments showed that the orbital velocity of the earth was not a factor in the speed of light emitted from these stars.
The only solution to the apparent pardox was that there was no paradox at all. The speed of light was the absolute from which all was measured and the time and distance had to change in order to have all observers see the speed of light in vacuum as the apparent constant it is.
One cannot travel faster than light because from a ship travelling at near light speed and headlights peer out ahead and SR says the light must travel away from the ship at the speed of light in vacuum. But on a planet the ship travels past, the headlights of the ship are also travelling at c, so the ship must be going slower than the photons from its headlights which are at v = c.
-
you guys need to smoke more dope
:D
-
Were there so advanced measurments at the time, - . measuring light travel at different orbital positions?
I mean, from a star straight across in the same horizontal line as earths orbit, the distance is about 1000 light seconds, or 16,6 light minutes if you prefer. Measured against just the nearest stars (4-6 light years), that is like a crowberry in hell. Please tell me more abouty this, like how and when and so, - very interesting!!!:) :) :) :)
-
Originally posted by Angus
Some Physics experts don't belive in the absolutness of the light speed. And as a matter of fact, danish scientists managed to "slow" down light to the stunning speed of only 100 km/h if my memory serves me right. REALLY!!
Not some physicists, all of them. Speed of light is not constant, c is.
Speed of light (not c, but the real velocity with which light propagates) depends on a density of the medium in which it travels.
-
Looking at the same star at opposite points in the orbit should have produced a velocity difference of over 133,318 mph (213,300 kph) due to the advancing and retreating of the earth's orbital velocity through the supposed ether. This was the biggest velocity difference anybody could think of and it probably still is a century later.
Observations showed that the velocity difference did not exist, and that caused Einstein to begin scratching his head.
An experiment was designed by Fizeau (1819-1896) to find the speed of light. A light beam is reflected to a distant mirror, passing through the teeth of a wheel rotating at high speed. The teeth cause a strobe effect, and the speed of the teeth is adjusted until the reflected pulse of light is stopped by the next tooth.
Time and distance of the apparatus is known so the speed is calculated.
-
Nobody has discovered or solved the mystery of why the max speed of light is c=299'792'458 m/s.
These thoughts culminated in the idea that there is no universal gridwork from which all is measured. Gridworks could be started anywhere, and all would be equally valid.
Speed of light and time (http://homepage.sunrise.ch/homepage/schatzer/space-time.html)
Followed by
Lorentz Transformations (http://www.angelfire.com/nj/FTLphysics/QCones.html)
-
Why is a difficult thing to prove scientifically.
Why gravity works, why electromagnetism works, many other 'whys' are all equally mysterious.
We can show that they are, and how they work, and discover the rules they follow, but why will be (probably) forever a mystery.
The speed of light in vacuum is the fastest speed because it is.
The closest answer may be 'Because God wanted it that way"... at least it is as good as an answer as anyone has come up with yet.
-
Well I think most people have heard about the standard explanation or theories on gravity (einstein). Here is a new alternative theory.
Autodynamics
Relativity (http://www.autodynamics.org/new03/autodynamics.html)
faster than light (http://www.autodynamics.org/new03/faster-than-light.html)
Gravity (http://www.autodynamics.org/new03/pico_gravitons.html)
Sounds a bit far out but click on the expert tab.
-
If you guys are so smart then explain this:
(http://www.muq.org/~cynbe/jpeg/wonderbra.jpeg)
-
For stuff like general relativity and quantum words are no good, you nedd something rigerous. i.e. maths
-
Originally posted by Holden McGroin
Why is it a difficult thing to prove scientifically.
Why gravity works, why electromagnetism works, many other 'whys' are all equally mysterious.
Well in order to further the search for answeres on gravity, the scientists are trying to alter it, affect it, or change it somehow or find clues indrectly. Even resolve known issues of the theory within other scopes of physics such as quantum mechanics where a gravity theory doesnt make sense or is difficult to achieve.
The speed of light in vacuum is the fastest speed because it is.
The brains are trying to slow light down and eventually push a particle faster then c.
The closest answer may be 'Because God wanted it that way"... at least it is as good as an answer as anyone has come up with yet.
Which god are you refering to?
-
Originally posted by MrCoffee
Well in order to further the search for answeres on gravity, the scientists are trying to alter it, affect it, or change it somehow or find clues indrectly. Even resolve known issues of the theory within other scopes of physics such as quantum mechanics where a gravity theory doesnt make sense or is difficult to achieve.
The answer to why is not a question for physicists, it is for philosophers. Physicists answer how.
Nobody knows why gravity works, it just does.
The brains are trying to slow light down and eventually push a particle faster then c.
What good is faster than light speed when light speed is only 55 mph?
Which god are you refering to?
The supreme overlord god of the universe, Fred.
And Vulcun, you see there are two genders in the human species, and in the image you presented represents the female gender.
-
A couple of articles on slowing light and even stopping it:
http://www.rochester.edu/pr/News/NewsReleases/scitech/boyd-slowlight.html
http://www.signonsandiego.com/news/science/20031209-2349-frozenlight.html
-
Originally posted by Hortlund
Why is the speed of light a constant, or an absolute. Doesnt that ...defy the laws of...something (see car/bullet analogy).
And how can light be both a wave-movement AND a particle (at least according to my old physics teacher). Something about a proton having a mass while travelling at the speed of light, but not having any mass if not travelling at that speed.
Not a physisist, but, i think light (energy) is transfered from molecule to molecule just like electricity goes through a wire.
Particles displace molecules. i.e. travel through space like a fish through water.
So, probably a terrible analogy but, if I were riding on top of a train going 200mph and I shot a laser beam, would the laser beam be going speedoflight+200mph? No. It would travel at the speedoflight in all directions from the point at which it originated since the transfer rate of light energy from molecule to molecule only happens so fast.
-
Not a physisist, but, i think light (energy) is transfered from molecule to molecule just like electricity goes through a wire.
I'm not a physicist either, but I know light can travel through a vacuum. The speed of light constant used in physics is the speed of light in a vacuum. Light travels more slowly through matter like air or water.
ra
-
In his book "A Brief History Of Time", Stephen Hawking explained the absolute speed of light very simply. It's not so much a matter of speed, but acceleration.
Here's the basis for his explanation: To reach a velocity, something must accelerate to that speed. To accelerate something takes energy. The more mass something has, the more energy it takes to accelerate it. That is newtonian physics. But newtonian physics neglects the affects of time and space... relativity. Relativity reveals that as an object gains speed, mass increases, so that at some point mass will approach infinity.
Ok, here's the simple part: As mass increases, it takes more energy to accelerate. When mass nears infinity, it takes an infinate amount of energy to accelerate it any further. Thus we have a natural limit to how fast something can travel, which has been measured as the speed of light.
It's called the speed of light because light is one of the few things we can normally observe that travels that fast. But light can and does commonly travel slower when it travels through some material, such as glass. How much it slows depends upon the affective density (transparency), length of time it travels through the material, and the fequency of the light. Thus the thicker the glass, the more light slows down. This is what makes lenses and prisms work... and sunsets.
My own observations: All this seems strange to us because space, time and mass are not what they appear to be. Mass isn't really some solid hunk of stuff that we see and feel, these are simple affects. For example, as you dissect an atom, you find an increasing number of smaller and smaller particals separated by relatively huge distances. Eventually the particals get so small they no longer have any mass to speak of. So when you completely dissect an atom, though it may be lead, you end up with nothing but the energy required to hold the atom together. Thus mass is not a solid material as it appears to be, but energy which gives it the properties we observe. So look not at the particals of an atom, the important part is the gaps between them... which is time and space... nothing but a relationship... relatively speaking.
grizzly
-
Originally posted by ra
I'm not a physicist either, but I know light can travel through a vacuum. The speed of light constant used in physics is the speed of light in a vacuum. Light travels more slowly through matter like air or water.
ra
Right, some molecules are less conductive than other molecules. That is why there are shadows. And of course, space is a vacuum and provides a perfect medium for light to ttravel.
-
Right, some molecules are less conductive than other molecules. That is why there are shadows. And of course, space is a vacuum and provides a perfect medium for light to ttravel.
So...
Light travels from molecule to molecule, like electricity goes through a wire.
Because vacuum is the absence of matter therefore there are no molecules, this makes vacuum the perfect medium.
Something of a problem in the logic here....
:confused: