[QUOTE=Darth Evad]good book. i just bought it for work. there's lots about light in there like what you're talking about.[/QUOTE]

Read his biographies - it'll add a whole extra dimension to path integrals and Feynman diagrams. Awesome dude.

Honestly, you're making up a lot of things, and you're posting them as facts. You REALLY need to take a physics class or two. The wormholes (which are ONLY THEORY AND HAVE NEVER BEEN PROVEN TO EXIST) have a gravity because of the intense concentration of the matter within the Black Hole, which is the theoretical entrance. The reason you'd get from one place to another in a wormhole is because Hyperspace is not the same thing as Space-Time and the speed of light doesn't matter there. Space-Time (hyphenated for ease of reading, not because it's the proper way to spell) is what we live in--our universe. So comparing the two is a very silly thing to do.

Also, your 'exotic material' bit is wrong. Einstein never proved that theory...I don't think he even made that theory. Hawking is the one that's expounded a lot on wormholes. I could be wrong. Either way, everything about wormholes is theory and what we've observed (or rather, havent' observed). In a black hole (the theoretical entrance to a wormhole) everything, even light is trapped at the event horizon and gets sucked in. Therefore we can't see anything after that. Theoretically it gets sucked in until it's so thin, only like an atom in width, that it passes through the singularity. In the singularity, however, the effect of Space-Time is warped so that time is infinite--nothing happens forever. The theory is that you would then pop out of a wormhole instantaneously because space-time is so warped in the singularity. The exit of the wormhole is a White Hole (how creative). However, how you would get through there is more likely to be as a pile of atoms than as a whole human being, as the singularity is supposedly only an atom thick.

Basically, the exotic material is not the source of gravity, the star collapsing in on itself and creating a black hole is.

Also, as Martyn says, black holes emit radiation, but only a little. This may be the tiny subatomic particles of an atom that entered being expelled from the black hole. So this could prove that there's also no such thing as White Holes, and no such thing as wormholes.

So yeah, you're making up a lot of stuff, and taking what's theory as fact.

Also, an airliner can go nowhere near the speed of light, .4C (or .4 times the speed of light). You're talking 119 986 983.2 meters per second here. The line of increase of mass/speed on the relativistic speed graph would be much like a very sharp upward turning exponential growth graph, like this



So as you see, it is somewhat like a parabola, you just thought the vertex was at some other point, and the assymptopes are x and y respectively, thus showing that the line could never cross The Speed of Light or Y, which would make sense as there's no such thing as negative mass, and according to Einstein's theory of relativity, nothing can go faster than the speed of light.

/random jarble of physics.

http://imagecorner.sorrowind.net

I never want to hear that excuse on these forums again!

Because motion is relative, if you are unable to move at the speed of light, wouldn't you also not be able to move at half the speed of light? If two things traveling at half the speed of light, relative to a third object, go toward each other, they would be traveling at the speed of light, right? I'm sorry if that's not very clear. : /

Relative to one guy, the other guy would be going the speed of light, TRUE, but relative to the speed of light, he'd still be going half the speed of light, which is what matters.

Matt, everything you're supposing is completely unsupported by anything but unsupported conjecture. Part of the misunderstanding here is that the Newtonian formula for kinetic energy is wrong as v approaches relativistic speeds. High school physics students learn KE = (1/2)mv^2. This holds true for the lower values of v we encounter normally. However, the relativistic model is KE = (1 = sqrt(1 - (v^2 / c^2)) - 1)mc^2. The definition of momentum states that momentum is equal to the integral of force with respect to time. In turn, the integral of momentum is kinetic energy. Looking at the equation for relativistic kinetic energy, as v approaches c, kinetic energy grows to positive infinity at an incresingly fast rate. Essentially, the force required to allow v to approach c becomes infinite.

The speed of light and absolute zero are just two values that are unattainable. People just don't seem to want to accept that.

Math time!

Look what happens as v approaches c. The denominator goes to zero. We can't have that! If v = c then gamma is undefined. Hence, save for photons, nothing can travel exactly at c.

Obi, I know what you're getting at, and this is where the real head-f*** comes into physics and optics in general.

Imagine you are riding on a light wave, that is going at 3/4 of the speed of light (0.75c) and that your friend is doing the same thing, and you are careering towards each other.

Now, if we were in a Newtonian world, ie the one we live and beathe in, you'd be approaching each other at a relative speed of 1.5c (0.75c + 0.75c). In this preconception you are utterly correct, but unfortunately in the world of light mechanics this isn't the case. Even light beams approaching each other at c only experience relative speeds of c.

So if you and your friend were on those light beams, you'd pass each other at the speed of light, and not a jot more.

Told you it was a head-f***!

Whaaaaaaaaaaaaaat? That's weeeeird!

So wait. Lets say you have 3 objects. Object A is flying towards Object C.

Object A and C are travelling at the speed of light but Object B is standing still.
How could Object A and C have a relative velocity of c when Object B would also have a relative velocity of c to both of them?

Because light is oh so special.

No really.

Ask one of the real physicists like Maeve or James Bond!

This thread makes me really look forward to my physics class that I signed up for next semester. Or not!

Relativity was a mind-**** to me as well. It showed when I got a low B on my test.

It all comes down to reference frames. I think it's easier to examine this type of problem at sublight like Martyn's speeds. And yeah, I suggest that James Bond help explain this.

JediGandalf: As per that mathematical equation you have so kindly shared with us, pray tell, where did that little-gamma come from in the first place? For, how conveniently it makes v limited to the value of c. Is it not merely just a way of building this relationship into the equation on the pretence that it is true, and not in fact, on the basis of a natural phenomenon?

Just wondering, how are we measuring c. I mean, wouldn't all of our measurements be relative to the speed of the earth?

Also, how can an object gain mass simply by traveling faster? It's not like they gain matter...

It is called the Lorentz factor. It is used in the Lorentz Transformations, time dialation, and length contraction equations. I do not know how the Lorentz factor was derived.

You're being ridiculous. You're acting as if there's some conspiracy to cover up something propogated by the entire physics community. If you were to experimentally have objects approach relativistic speeds, and graph force vs velocity or something of that nature, you would find that there is an asymptote such that the required force approaches infinity as velocity approaches c.

The situation you've described has already been simulated in real life, thanks to space travel. The air in the space shuttle, for example, still exerts a pressure on the human body equal to the outward pressure exerted by the matter inside the body. This despite a virtual absence of gravity.

That's because the air is trapped within a closed container, the cabin. If the Earth somehow stopped exerting gravity, I imagine there would be nothing to hold the air from fleeing into space.

I've not taken physics yet. this is going to be a hard subject.

Obviously. I'm just correcting his claim that gravity creates the pressure that keeps us from exploding.

Gravity sucks air down do earth. The gravity is stronger at the bottom, pulling more air down there. Spaghettification, on a smaller level. More air cluttered at the bottom, more pressure exerted by it on other things.
Same with water. The weight of the water on top makes the water on bottom so clunched up together, exerting massiv epressure on surrounding materials.
***
And this whole thing about being able to slow C down... it reminds me of K-PAX...
Dr. Mark Powell: What if I were to tell you that according to a man who lived on our planet, named Einstein, that nothing can travel faster than the speed of light?
Prot: I would say that you misread Einstein, Dr. Powell. May I call you Mark? You see Mark, what Einstein actually said was that nothing can accelerate to the speed of light because its mass would become infinite. Einstein said nothing about entities already traveling at the speed of light or faster.

-Ok-ish movie.

Yep, they are, so which is why you use an inferometer, which measures speeds in both directions from the earth (orthagonally) and you repeat it for different times in the earth's orbit, and you STILL find that c = 3x10^8 ms^-1.

The Michleson-Morely experiment is where this all started, with an attempt to prove that there was an ether through which light waves travelled (because all waves need a medium).

Fascinating stuff, and well spotted there SG-Fan - you'll make a great physicist if you take it

All of you shut up!













...quit reminding me of school.

[cue cheesy cartoon music] Here I come to save the day! [/end cheesy music]

K, firstly I will not be answering these questions because I'm a lazy arse, but my girlfriend will as she just happens to be at my house as its my birthday tomorrow.

Why my girlfriend? because she is a year older than me, graduated this year from Queen Mary with a First Class Masters Degree with Honours in Astrophysics.

Can I also say that I had such a great laugh reading some of the posts, Yoshi did a good job till relativity came up and martyn has explained most things quite well.

Anyways, here’s Jo, don't argue with her, she gets mad....she's just hit me now...ouch...I must move now...

-----------------------------------

Hi, a couple of things came to my attention during this thread but I'll try and keep it short...

- correct, particles have to be mass less to travel faster or at the speed of light, this is why light does it, it doesn't have mass, IT'S (also) A WAVE!! This is why it is not effected directly by forces, it's a wave in electromagnetic fields, although it can be bent by them. An example: when there is an eclipse, you can see the stars that are actually behind the sun.

Particles such as neutrinos travel at nearly the speed of light, somewhere around .9c, but they have very tiny mass so can't travel at the speed of light. Their small mass is also what makes them very hard to detect as they do not interact with matter very strongly. If there were particles travelling faster than the speed of light, we probably wouldn't be able to detect them anyway with the current technology.

On a slightly different note, there is a theory that there exists a Higgs boson that interacts with all matter giving it mass and that the particles themselves do not have mass... this is the basis of string theory and is a requirement of the standard particle physics model.

- next, wormholes. Now it's correct about the spaghettification, but a normal black hole destroys what goes in. If it comes out of a theoretical white hole, it would be energy. A wormhole would only exist if the black hole were rotating so that the singularity in the centre would be a ring. The person would have to travel through the ring to travel through space and time overcoming weight gain (approaching infinite mass) becoming shorter (length contraction) and taking nearly forever (time dilation) as time is not a constant either, which is why the speed of light is.

The speed of light was shown constant by Maxwell's electromagnetic formula. c = 1/( permeability of free space x permittivity of free space) both of which are constant.

Also, if there was "reverse gravity" holding up a wormhole, how do you suppose we "walk through" as all particles would be pushed towards the walls and we would get ripped apart as discussed in the "earth without gravity" debate, which by the way would destroy the earth in the process. No gravity = no atmosphere and no planet.

- Next up, relativity. The (gamma)m represents relativistic mass, the normally referred to E=mc^2 represents rest mass energies and we're talking moving ones. And another *theoretical* example/question... if you're travelling at the speed of light and you look in a mirror, would you see your reflection? If you think no then you are invisible which is false. You DO see your reflection as the light from your face travels at c to the mirror which bounces back at c to you. Thus, the speed of light is constant irrelevant of where you are and how fast you travel. The proof: Relativity has a postulate that says, "the laws of physics are the same in all frames of reference" so Maxwell’s law still stands and the speed of light is still c.

Hope that answers some of this thread, I don't mind debating the science, helps me learn to explain it better. And for once, James agrees with me on this bit of science. This not ask him about the "Why everything goes round the sun in the same direction" debate :o) Sorry, this wasn't as short as it was supposed to be.

-----------------------------------

back to normal old me now, we don't always agree on things, i personally think Jo sticks far too rigidly to confirmed ideas, but then I always like to believe things like Star Trek and Star Wars could actually be possible, so maybe i'm just a day dreamer....

As we can only currently account for 10-20% of the known (thoerised) mass of the universe, there is still a big window for stuff to exist that we may not currently even know about.

[QUOTE=James Bond]big post[/QUOTE]

Yeah, I blame only having had high school physics. Lame thing to blame, I know :p

Yay dark matter!

[QUOTE=Dj Yoshi]No, Matt, I don't think you get it. As you approach the speed of light mass increases--this is what Detty said. It's a law in the physics world. It's been proven many times. And theoretically, if you ever hit the speed of light, your mass would become infinite. Of course, nobody's been able to prove this since the only thing that travels as fast as light is well...light...

Here, read up.[/QUOTE]

Actually, they've supposely have been able to accelerate muons to .97c (according to the college physics book I had), though I have not yet been able to varify this (among many other experiments related to relativity). If it is true that they were able to do this, then it would certainly disprove that velocity and mass are relative in the sense that Eistein describes them (as the muon would have had an extreamly large mass). The experiment was meant to prove the effects of time dialation, btw, and there was know acknowledgment of the mass of the muon increasing (only it's life time...which, btw, if the experiment is true, I can easily debunk that element as well).

This isn't totally accurate. In particular the: "It's not just a straight linear 'mass increases as speed increases' because you'd notice as you flew in planes or whatever. The effect is minimal until you hit relativistic speeds at around significant portions of C (~0.4C if memory serves), and then the effect of mass gain becomes not only noticeable, but crippling to further accelleration: F = ma."

It's not velocity that causes you to go back in your seat. For that matter, it's not a "force" either. Acceleration (and it's important to note here, that this is only true in a non-vaccum, gravity present environment...it's slightly different in deep space enviornments where they are not a factor). Although it's against traditionaly held scientific belief, what actually causes you to go backwards in your seat has to do more with how your body is constructed versus how the plane, car, train, whatever is constructed. Human material has a lot more "give" (that is to say, more elasiticy) in it then the metals and other solid materials used in planes. The greater the elasticity, the more time it takes for tension to be created from one molecule in the substance to the next (adjacent) molecule. In short, the time it takes all of the molecules at one end of the plane to all of the molecules at the other end of the plane to move x distance is far less then the time it takes the molecules in your feet (that are somewhat connected to the plane) and the molecules in your head to move the same distance. In fact, the molecules at the bottom of your feet move distance x in approx. the same time as it takes the molecules in the plane directly under it to move the same distance x. However, it takes your head x + (the time for tension to be created from the molecules at the bottom of your foot to the top of your head to travel the same distance). THIS is why your head goes back into the seat while the plane is accelerating (not, so called "G Forces"...though maybe you could call it "T Forces" where T is for Tension). The proof of this is simple. Regardless of whatever speed the plane levels out at (stops accelerating to travel at a constant velocity), your head is no longer pressed against the seat and you can now move it as freely as your feet. Of course this could also be simulated with water or any other non-solid.

I don't think you understand what he said. He's saying that there is no significant change in mass until you reach VERY high speeds, such as 0.4c, because mass doesn't increase too much until it hits that point on the curve. Someone else posted a graph earlier, go check it out.

He's not saying anything about acceleration in airplanes. He's saying that your mass isn't changing enough when you travel at the velocity of an airplane to notice it because in terms of relativity it's hardly faster than standing still.

Actually, he was using the example to illustrate the effects at higher accelerations (which he later admitted was a bad example). I however, was pointing out in his example (as is and not sctrickly in reference to the initial purpose of the example) that it is not gravity or a mysterious "force" that causes those effects on the human body. By the debunking the currently held belief that it is caused by gravity and/or "g-forces" it paves the way to debunking the above equation (and it's graph representation). In short, however, the above equation is only valid for objects in an environment similer to that of earths. It's principles are derived from the observation of acceleration on earth. However, the observation of acceleration and constant velocity are much different then that in the deep reaches of space...which is where newtonian physics is based on. In other words, the "once in motion always in motion" doesn't apply on Earth. However, a constant acceleration that maintains an objects velocity is ofter misconstrude as constant velocity. If you applied the same amount of constant acceleration in space, the result would be constant acceleration. In other words, it does not require energy to maintain velocity in space. Additionally, because of this, it has some interesting changes on how we preceive "inertial frames" and the differences there in. Due to this, the equation above is flawed because v only increases after an occurances of an a (which is a delta v / delta t OR a change in velocity over a change in time. In the case of a spaceship, this can occur in burst periods, where each burst represents an instance of acceleration and the time between each burst represents periods of constant velocity. In these periods of constant velocity we find that, while to an outside observer or an inside observer looking out, it may appear that they are traveling at velocity x, as far as the ship structure and crew are concerned, it is clear that they are traveling at a relative velocity (right down to the molecular level, and don't confuse my use of "relative" with those associated with the theroy of relativity unless I specifically state so) of 0. So, we now learn that not only does the equation does not include the descripancy between v and a, but, it only "true" from the perspective of an observer. And it is! An observer watching a ship accelerating to the speed of light would observe the object increasing in mass. The ship would then disappear one it reached the speed of light and the observer would no longer be able to observe it. THIS IS BECAUSE OF THE RATE AT WHICH LIGHT TRAVELS ONLY! THIS EQUATION IS TRUE FOR OBSERVATION PURPOSES ONLY! Which was Eisteins intent. Everything in relativity was meant to explain how to calculate events occuring realtive to an observer. Which, unfortunately, is only half of what is needed in the scientfic world, yes, we need to be able to calculate and understand what the observer is seeing, but we also need to know what the observer in the other frame of reference is experiencing. Unfortunately, even this was explained by Einstein from the perspective of the stationary observer. I short, the bottom line is to realize the differece in what is being observed and what is actually happening (or is possible).

As far as objects accelerating in space: In the case of a space ship expending fuel, it would actually be losing mass as it accelerates (even though it would appear from an observer that it was increasing in mass).

Your English teacher would have a fit if you wrote a paper like that!

I was just trying to get the basics over to Matt - I'm no physicist, I am however a structural engineer who once upon a time studied physics.

Oh, and until you learn to organise your thoughts and occasionally press the enter key, I'm not gonna even ATTEMPT to read that block of text, because (a) I can't be bothered because of the layout, and (b) it's probably picking apart what I said, and like I just said, I don't pretend to be the expert - which is why I invoked the JB.

EDIT: Skim reading tells me that you may think I was talking about G-Forces in planes - I was not, and am perfectly aware of the effects of accelleration: I was talking about relativistic forces, and trying to bring it down to Matt's level.

[QUOTE=James Bond]Lots of physics[/QUOTE]
*applauds the gf*

Thank you for setting us amateur physicists straight.

... I have absolutely nothing constructive to add to this discussion, except...

[QUOTE=Raoul Duke]You have no proof whatsoever, infact all rules of psychics and science go against your claims, yet you just believe this?[/QUOTE]

YOU ARE BREAKING THE RULES OF THE PSYCHICS. MISS CLEO IS ANGRY.

Actually, my emphesise was on the fact that, while the force equation (F=ma) can be helpful in summerizing (mathematically), it doesn't truly exist. It works wonders for esitamating the effects that two objects will have on each other, but contains absolutely nothing of what actually cause the effects. This also applies in gravitational force (F=mg). The traditional line of thinking is that if a book is on a table, it applies a downward force of mg and the table exerts an upward force of -mg. This is absolutely rediculous. In actuality, the book exerts a downward "force", however, it's the tables strong molecule alignment (elasticty and tension considered) that supports the book and not the upward force exerted against the book. Given time, the book will eventually break through the table as the tables molecular strength begins to weeken over time. Likewise, houses settle over time, because the ground's strength (in tension) is constantly changing (due to rain and other factors), under the weight (considered mg) of the house.

Ok, don't even bother to tell me about soil mechanics, especially when you liken it to a book resting on a table. Why should the table fail first? Why would they not just blend into each other?

House settlement is caused by lots of effects, including consolidation, ground water flow, slip surfaces and geological change. You cannot begin to compare it to a book resting on a table.

Also, houses are typically made of solids, and are resting upon a granular medium. Books and tables do not share these properties.

Shoot, this kid is about as bright as brown crayon in a box of glowsticks.

/me shoots self in face in exasperation.