After viewing almost all of the previous posts, I still do not understand why normal objects cannot go as fast/faster than the speed of light. Please do not respond with e = mc^2 or any other explanation about photons or subatomic particles that i dont understand. just please explain why light (a physical object like anything else) makes mass go to infinity. why does everyone feel compelled to accept this weird rule that has never been tested?
also- if i were in a spaceship going one mile per hour slower than the speed of light, and i started running to the front of the spaceship from the back at 2 miles per hour, would i not be going faster than light?
[This message was edited by coldfuse on 02-17-03 at 09:17 PM.]
I'm not sure how best to explain it to you. If I think of a way, I will post again. It's not an easy concept to understand, especially non-mathematically.
I did want to clear up a few misconceptions, however. Light does not make mass go to infinity. Light is not a physical object *like any other*. It has no mass, while most objects do.
********* As far as testing the rule, the theory of relativity has been extensively tested, and based on the comparison of predictions to experiment, many physicists view it as the most successful theory in physics because of how well it has held up to experiments. *********
As far as your hypothetical, the math you asked me not to use demonstrates that you end up going 2 miles per hour with respect to the shuttle, but the light still ends up going at light speed with respect to you. (like I said, it's not an easy concept to explain, especially non-mathematically). ++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++ 02-17-03, 10:12 AM Tom-Ying regarding the hypothetical spaceship question: ahh, i see. i get that.
but i still don't understand the concept of requiring "infinite energy" to propel an object because it will have infinite mass.
lets say, hypothetically (i dont know the actual e=mc^2 conversions here) that i throw a baseball and it takes 10 joules of energy to propel it at a certain speed. now lets say i want to increase that speed with my next baseball and i throw it with 100 joules. it would go alot faster. why is it that as soon as my speed reaches the speed of light, i need infinite joules? wouldn't that proportion just continue? why does it reach infinity at light speed? light is just like anything else, why is it the boundary?
02-17-03, 10:13 AM Tom-Ying feel free to use some math to explain this if neccisary. i think i can get it if it stays relatively simple Smile
02-17-03, 10:23 AM methos I'll leave out the math (mostly because i don't want to look it up and typing equations is a pain). You asked, "why is it that as soon as my speed reaches the speed of light..."
That's the issue. It doesn't just suddenly increase.
The proportion does continue, but it is not a simple linear proportion (i'll spare us both the equations). It increases as you go faster and faster in such a way that it approaches infinity as you approach the speed of light. At the slow speeds we are used to dealing with (even supersonic jets are moving slowly with respect to the speed of light), the effect is too small to notice, but at speeds closer to the speed of light, it is noticeable.
02-17-03, 11:52 AM methos As i said above, relativity produces effects at speeds that are only fractions of the speed of light, and those effects get larger as you get closer to the speed of light. To give you an idea of how fast this is, sound moves a few hundred times as fast as you walk, but light moves about a million times faster than sound (and a few hundred million times faster than you walk). With very precise instruments, we can measure relativistic effects at a few times the speed of sound, and this is only a millionth of the speed of light.
btw, you've more or less stated the "Bohr Correspondence Principle." It basically states that any theory has to agree with classically theories (like Newton's theories) when it is applied to the scale we are used to. Relativity satisfies this, as the difference between the predictions of Newton's theories and Einsteins theories at speeds we are used to dealing with are so small that they cannot be measured.
02-17-03, 04:20 PM Tom-Ying
quote:Originally posted by methos5000: ...It increases as you go faster and faster in such a way that it approaches infinity as you approach the speed of light...
yes. but why? why does it approach infinity at the speed of light?
If I had a graph that plotted energy required to propel an object on the Y axis and the speed you are reaching on the X axis, the curved line of the graph would continue upwards and to the right until it hit the X boundary of the speed of light, where that line would go upward and upward, a steeper and steeper slope- never actually hitting the speed of light. but why? is it just one of those laws we have to accept? it seems to me that light is similar to sound-- an abstract medium of the universe, but one that we can out-speed. why not light? why does everyone assume light is the fastest thing there is? i still do not understand this. maybe i never will. Confused
02-17-03, 04:33 PM methos Why specifically that speed? Nobody knows. Perhaps one of the new theories like M-theory will be able to answer that. As to why there needs to be a limiting speed, it basically comes down to this:
as long as you are moving at a constant speed, there is no way to distinguish whether you are moving or the rest of the world is moving around you (think of the fact that we are actually speeding through space with respect to the sun right now). The only reference that is the same no matter how fast you are going is light. light reaches the fastest possible speed because it has no mass, unlike most other things. no matter how fast you go, you will always measure it as going the speed of light faster than you. In order for this to be true for both someone standing still and someone moving with respect to them, strange things have to happen. Einstein predicted these strange things and they have all turned out to be true.
basically, it comes down to that light always seems to go the speed of light faster than you no matter how fast you go, for this to remain true, you can never go the speed of light.
02-17-03, 06:42 PM Tom-Ying i guess that is what it comes down to.
but, another question in this thread asked "what is light's fuel?" and the answer is obviously the chemical reactions that take place. so, why is it that we couldn't build some kind of engine that could replicate and synthetically emulate those reactions? (patent pending! Smile ) i guess these are questions that may never be answered. thanks for the help, though!
02-17-03, 07:26 PM methos the idea of "fuel" for light is not really valid. Fuel is only neccesary to accelerate something. Light does not need to accelerate as it is always moving at the speed of light and is not slowed because it doesn't have mass. What it comes down to is that we have mass, so we can't be accelerated to that speed.
02-19-03, 06:09 AM Pin~Jinx HELLO NEIGHBOUR good thinking there_that why does the speed of light have to be the boundary & "why is it that we couldn't build some kind of engine that could replicate and synthetically emulate those reactions?" It is pretty amusing to see a fertile and working mind (let's just hope that it doesn't detract, but stay on the right lines).
T-Y, you'll have to get this through your mind that light is NOT like "anything else" it is rays or packets of energies (the theory is still un-determined though) but as light does not have any mass which enables it to require minimum possible momentum to move, it has the Highest travelling speed.
One Pointer : this evaluation that light travels fastest has been tested and basing upon this fact, is applied in various things aswell. Pin~Jinx / anarchist
02-19-03, 07:15 AM methos Good answer Pin~Jinx, but I have one correction: you said, "it is rays or packets of energies (the theory is still un-determined though)" The theory is very well determined. It is both waves and particles (just as everything is, it just happens that the wave character of light is more significant than the wave character of a pbaseball)
02-19-03, 09:19 AM FlyingHellfish
quote:Originally posted by Tom-Ying: i guess that is what it comes down to.
but, another question in this thread asked "what is light's fuel?"
As Methos already mentioned, the concept of light being "fueled" (or propelled by some Force) isn't really valid. Since the speed of light is constant, light never accelerates. Relating this to a simple classical physics equation (Force = Mass x Acceleration), if the acceleration of an object is 0, then there is no force being exerted upon it.
In reference to your very first question as to why no object can travel faster than light, I'll give you a non-mathematical reason why. The closer that an object gets to the speed of light, the slower time moves for it. Using the astronaut example, say there's an astronaut traveling to a star 20 light years away at a speed very close to the speed of light. For the rest of us here on earth, 20 years would pass before the astronaut reached that star, but for the astronaut it might only take a matter of months. Relativity theory says that both frames of reference are equally valid and the laws of physics have to be the same for each. If that astronaut had been traveling at exactly the speed of light, the trip for him would have been instantaneous regardless of how many years it would seem to take on earth. You see a pattern? The closer to the speed of light the astronaut gets, the shorter the trip takes in his time frame of reference. Once he hits the speed of light, the trip becomes instantaneous. But what happens if he made the trip at a speed greater than that of light?
Take a more commonplace occurence. Say you're throwing a ball against a window. If you throw hard and fast enough, the ball will get to the window quicker and the window will break. Imagine if you could throw the ball at the speed of light. From the ball's frame of reference (which is as valid as yours), the act of your throwing it and the act of its breaking the window occurs simultaneously. Now, what if you could throw it at a speed greater than the speed of light? That means the ball would break the window before you threw it. Obviously, this contradicts every logical cause/effect rule there is, so as far as Logic is concerned, it's not possible.
02-20-03, 05:13 AM Pin~Jinx thnx M5k! A li'l praise here and there always pleases!!! Aaahm, according to my knowledge, the exact nature of light is still uncertain and there are just a few theories going about_however, you may be right too. (As I once mentioned earlier, I am neither a Physics teacher nor a Phy-student, so I am unfamiliar with the apt terms and the latest theories and stuff_not my business, you see.)Well, I'll get back to you on it, InshaAllah.
Bryan,[B] you did it again! The way you presented it, it most certainly makes sense (even to an air-head non-Phy damsel like me...!) [b]Tie you get it too, right?
Nevertheless, you are at the right place Big Grin Pin~Jinx / anarchist says NO WAR!
02-26-03, 09:42 PM DvdGStwrt Nothing is stopping matter (mass) from traveling faster than the speed of light.
The problem is traveling at the speed of light. Einstein never did finish the thought - I think he did that intentionally, I suspect he had a glimmer of something far worse than the atomic bomb - and take it through, and the rest of the world still debates whether or not mass/matter can travel faster than the speed of light (c).
The Problem.
As one approaches the speed of light (c) three things take place.
distance becomes smaller, time slows down (relative to the outside observer who will see everything in the ship going slower, the traveler in the ship will see everything at relative rest speeding up), and mass becomes greater. (Mass and weight are too different things, weight is caused by gravity pulling on a mass Wink)
At the Speed of light, distance becomes nil (0), Time Stops, and Mass become infinite.
Everyone complains at this point saying that the ship would need an infinite mass of energy to propel the vessel.
However, I would like to point out that any vessel approaching c would have its fuel approaching infinite mass.
Cheers
David
PS - Assuming that E=mc2 (energy = mass times the speed of light squared) can be a pure conversion for any engine, we can assume that the mass used as fuel at light speed would have a greater m therefore resulting in a greater E.
02-26-03, 09:48 PM DvdGStwrt Oh - Before I forget again, Einstein did leave the equation open for faster than light travel. Not even Mr. Hawking can say 100% that no matter/mass can travel faster than c. (Look up Tacyons for more information on that) The trick is passing through the c barrier.
Einstein and Rosen thought up the Einstein/Rosen Bridge, which on Star Trek is called a 'Wormhole'.
Modern Science says its possible, just not probable that one can create and focus and maintain a usable wormhole for any significant length of time.
However others have proposed that one doesn't need to keep it open for very long, just long enough to span the c barrier by passing the velocity of the vessel through an instantaneous, 0 distance wormhole which is just a flicker of a thing pushing the v of the vessel to c+.000000000000000000000001 - which brings in a whole new slew of physics problems.
Cheers
David
02-26-03, 10:00 PM DvdGStwrt Why? Well Just Because.
Not a Good answer. Ok. Let us look at light. Photons
They display the properties of particles (protons, neutrons, leptons, etc.) and wave forms (ie radiation, radio waves). They are contradictory in that they do this.
Light travels at the speed of light (c) approx 186,000 miles per second. The instant a photon is created (via chemical, nuclear, etc. energy) they are instantly traveling at c. There is no acceleration - in most cases (Gravitational wells affect the speed of light, for instance near a black hole the gravity (g) can stop light - mass can slow light due to g forces, or even bend the light in its travel).
It is due to the duel and unique nature of the photon that it does travel at c.
As for Formula, try this address http://www.friesian.com/separat.htm for the formula for time dilation and the rest of the wacky things that happen as we go faster.
David
PS - Remember speed kills. LOL
02-27-03, 08:43 AM FlyingHellfish
quote:Originally posted by DvdGStwrt: Nothing is stopping matter (mass) from traveling _faster_ than the speed of light.
The problem is traveling _at_ the speed of light.
That's true, or more specifically, crossing the threshold of the speed of light is what causes problems.
Some equations point to the existence of tachyons, hypothetical particles that are constantly traveling at speeds greater than the speed of light. The question is what is the nature of these particles, if they do in fact exist. The following equation:
E = mc2/Ö(1-v2/c2)
naturally implies that as the speed of an object (v) increases, so does the energy. If the object is traveling at the speed of light, the denominator becomes 0 and the energy is infinite. However, in the case of tachyons, v is greater than c, so v2/c2 is greater than 1, and 1-v2/c2 is a negative number. The square root of a negative number is an imaginary number. For example, let's say we have:
E = mc2/i
or put differently,
E = mc2*i-1
If the energy measured is to be a positive, real(and therefore measureable) quantity, the i-1 has to be cancelled out somewhere. c2 is a real constant, so therefore the implication is that the mass of a tachyon has to be imaginary.
What all of this means is that if an object is to cross the speed of light barrier, then the nature of its mass would have to change also, from a real quantity to an imaginary quantity.
Unfortunately, we currently have no way of directly detecting or testing for the existence of tachyons-we don't have an imaginary balance Smile Only slight aberrations in certain complicated equations imply that their existence is a possibility.
03-03-03, 02:49 PM babthrower Tom-Ying, here is a different approach to the problem.
But first I have to lay down a little background.
Physics is science, and science is the study of the material world i.e. that which exists outside of the mind.
The most powerful tool of science is mathematics.
Newton observed the actions of the bodies in the solar system and invented a mathematical language, calculus, to describe the motions.
He made observations, but he recorded them in mathematical formulas:
Fg=G((m1*m2)/r2)
Fg is the force of gravity m1 and m2 are the masses of the two bodies G is the 'universal gravitational constant', which is the intrinsic strength of the the gravitational force.
Newton's math was wildly successful at predicting the motions of the planets.
He set a precedent. From his age until ours mathematics is used in physics to represent forces and masses in action.
Einstein was just continuing the tradition.
When Einstein stated E=Mc2, he was saying that the amount of energy released when an atom is split is equal to the atom's mass multiplied by the number called 'the speed of light'.
Now, once we have a mathematical statement, we can perform conversions according to 'rules':
x2 + 2xy + y2 = (x + Y)(x + y)
When we translate the converted formula, we may find surprising results. The results follow mathematically .
But does that mean that the results which actually occur in the external physical world are what we might expect based on the 'translation' of the math into English?
That is unknown. So the physicists watch for confirmations of the statements in the real world. Einstein's math showed that light has 'mass'; how can that be, if light is pure energy? Yet light from the star Vega was observed to shift as it passed close to our sun during an eclipse, just as if the light were gravitationally attracted by sun's mass.
This observation 'supported' Einstein's theory, but did not prove it.
So: the conclusion is we will not know if it is impossible for anything to go faster than the speed of light until we test it.
Still, some scientists regard such theories as 'fact' if they are very well supported. Devising the atomic bomb gave further support to Einstein's theory.
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