Ok, even though I know some basic pricipals of physics, I deal with people who know physics very well all the time, even debate physics alot because of what I know from private study, I still have one very basic question...

WHY CAN'T ANYTHING WITH MASS TRAVEL FASTER THAN LIGHT? All I keep hearing is that objects mass becomes infinite as they approach the speed of light, because of the increase in the kinetic energy of an object as it moves faster and faster. I still don't understand how that happens if light as a set speed limit. If the speed of light is 300,000km/s, then how come something can't move 300,001km/s? I don't understand that basic principal. How can the mass of an object increase to infinity, when the speed of the object isn't infinite?

I've asked this question for years, and the only thing they say in layman's terms is simply "it is, or it isn't." when they try and actually explain it, they use terms that I have no clue about, because I'm neither a physicist, nor a physics student. I have no idea what they are talking about.

If it is possible to explain in layman's terms, than can someone please do it for me.

P.S.- Can NOTHING move faster than light that has mass? No even protons, neutrons, and electrons?

Originally posted by BetweenThePoints


P.S.- Can NOTHING move faster than light that has mass? No even protons, neutrons, and electrons?

That's the general idea of it.

Wait...... Maybe we can relate this to the problems when we are trying to go faster than sound, but I can barely make up the theory. I can just provide the possible facts.
Suppose there's a matter which is either irradiative and not pure 'black' or radiative and black. Either way, either the matter reflect any EMW or emit EMW, but when the matter moves fast enough, it the EMW will relatively 'slow down', to such a degree that both matter and EMW move at the same speed and more.
When the matter moves almost as fast as EMW, the EMW it emits accumulates, and making a 'wave barrier' in front of him (because it emits EMW constantly). When it finally goes as fast as EMW, the wave barrier becomes so great, the matter needs great energy to overcome this barrier.
What do you say?

Originally posted by BetweenThePoints
Ok, even though I know some basic pricipals of physics, I deal with people who know physics very well all the time, even debate physics alot because of what I know from private study, I still have one very basic question...

WHY CAN'T ANYTHING WITH MASS TRAVEL FASTER THAN LIGHT? All I keep hearing is that objects mass becomes infinite as they approach the speed of light, because of the increase in the kinetic energy of an object as it moves faster and faster. I still don't understand how that happens if light as a set speed limit. If the speed of light is 300,000km/s, then how come something can't move 300,001km/s? I don't understand that basic principal. How can the mass of an object increase to infinity, when the speed of the object isn't infinite?

I've asked this question for years, and the only thing they say in layman's terms is simply "it is, or it isn't." when they try and actually explain it, they use terms that I have no clue about, because I'm neither a physicist, nor a physics student. I have no idea what they are talking about.

If it is possible to explain in layman's terms, than can someone please do it for me.

P.S.- Can NOTHING move faster than light that has mass? No even protons, neutrons, and electrons?

The crux of the matter starts with the fact that the speed of light does not vary from observer to observer. IOW, if I shine a flashlight away from me, I will measure the light moving at 300,000km/s relative to me. Anyone else would measure the same light as also moving at 300,000km/s relative to themselves, even if I were moving relative to them.

This behavior of light leads to two observations between moving objects. Time dilation and length contraction. Objects moving relative to each other will measure each other to be shorter and having each other's time move slower.

We don't normally notice these effects because they don't become large enough to measure until the relative velocities become a fair fraction of the speed of light.

Taking these effects into account, we have to modify the classical formula for energy of a moving object:

E = mv²/2

to a new form:

E = mc²/sqrt(1-v²/c²)

One that shows that as v increases approaches c, E approaches infinity. Meaning that an mass must have infinite energy to travel at c.

Now the above explanation skips a lot of the details, but to give it the proper treatment would take a lot more than I am willing to devote to one post.

Wow, sargentlard, your statement helped me with nothing. You basically said "that's the way it is." That's not an explanation.

Now,Janus58, Your explanation would work, If only I had any idea what the last equation meant... Sorry, but I did say that, although my interest in physics is great, and I understand many of the concepts, I don't know any details, which is why I posted this question to begin with. Ok, Ok... I can understand most of it.. but what the hell is sqrt? If I knew that, I would understand the whole post.

Originally posted by BetweenThePoints


Now,Janus58, Your explanation would work, If only I had any idea what the last equation meant... Sorry, but I did say that, although my interest in physics is great, and I understand many of the concepts, I don't know any details, which is why I posted this question to begin with. Ok, Ok... I can understand most of it.. but what the hell is sqrt? If I knew that, I would understand the whole post.

sqrt means squareroot. You take the squareroot of the expression inside the parenthesis.

If you look at the part in the parenthesis (1-v²/c²)

c = the speed of light
v= the velocity of the mass. (m)

As v gets closer to c, v²/c² gets closer to 1, and 1-v²/c² gets closer to 0.

And as this happens the entire equation approaches infinity.

The problem is that to accelerate an object with mass, you need to somehow provide kinetic energy to the object (e.g. by pushing it, or using a rocket engine). Relativity tells us that the faster it travels, the more energy you need to put in to make it go just that bit faster again. And to accelerate it to the speed of light would require infinite energy input, which is obviously impossible.

Relativity doesn't really say nothing can go faster than the speed of light. It just says nothing with mass can be accelerated to the speed of light.

because?
Maybe that's the initial question: What actually hinders matter to go as fast as light? I know, I know, all physicists tend to answer with the help of relativity theory, but why? What is the TRUE reason for that, aside from any related theories available?

I just told you.

Sorry if I seem to be too demanding, but all those classical answer start to dissatisfy me...... Like, what makes a matter require infinite energy just to accelerate to such speed?

Exactly my question Curioucity, only put much simpler. WHY does it take infinite energy to reach 300,000km/s? Especially since light has a finite speed.

Oh, and Janus, thanks. I've never seen someone use "sqrt" instead of the standard square root sign before. That clears up alot in your equation. But back to the top part of my post, and Curioucity's post, the question is why. People always answer with the "special relativity says so" but obviously objects with mass cannot travel faster than light simply because "it says so" . ofcourse I don't think I've ever read relativity. It might help, but again, I probably wouldn't understand the language as einstein would rationalize it, I need the explanation in layman's terms. Equations and references to Relativity don't help at all. I need an in depth explanation.

James R.- As you would see in my original question, I already know that relativity says only objects with mass can't go faster than light.

I think I actually get it Janus... I tried out the equation on a calculator... and the final result never quite reaches 0, unless ofcourse it's the speed of light itself. Wow... it's infinite because it can never quite get there, and when it does, it's 0. I guess that's all I needed; to try the actual equation out. Cool. Thanks.

Originally posted by curioucity
Sorry if I seem to be too demanding, but all those classical answer start to dissatisfy me...... Like, what makes a matter require infinite energy just to accelerate to such speed?

The quick and dirty answer: It's the way the universe works.

It all basically derives from the fact that the laws of physics are the same for everyone regardless of their relative motion. The speed of light relies on two fundamental constants. Since these constants are the same for everyone, everyone measures the same value for the speed of light.

Since this is true, our concepts of time and space must be changed so that they are relative rather than absolute. This in turn logically leads to the fact that the energy of a mass changes with velocity in such a way that it nears infinity as the velocity nears c.

Each step is a logical conclusion of the one before it.

Same ol' classic........

"Why does a brick fall to the ground when I drop it?"

"Due to gravity."

"But why does it REALLY fall?"

"Well, the laws of gravity say that every two objects in the universe with mass attract each other according to an inverse square law. The Earth attracts the brick, and vice versa."

"Yes, that's the standard physics answer, but I want to know the REAL reason."

"Nobody knows. It's just the way the universe works. Physics describes what happens, not the ultimate 'Why'."

"That's such a typical physicist response!"
---------

Question: What kind of REAL reason would satisfy you?

Fine, you hit me with that. Satisfied? I guess I'll be running away from this too deep theories.

Originally posted by curioucity
Same ol' classic........

Okay, let's see if I can paint you a picture.

Every piece of matter has mass. One of the properties of mass is inertia, or the resistance to change in its movement.

A property of a moving object is energy. The faster an object moves, the greater its energy, and the more massive an object is, the more energy it takes to change its velocity by a given amount.

One of the things that we've discovered is that mass and energy are closely related, and are really just different ways to look at the same thing, and an object's energy also contributes to its inertia.

Thus if you start with an object at rest, and add y energy so that it is now moving at x ft per sec, the added energy increases the object's inertia. This means that it will now take even more energy to increase the object's velocity by another x ft per sec. This increases the inertia even more, requiring even a greater input of energy to further change the object's velocity, etc...

As the energy requirement for further acceleration goes up, so does the inertia. the resistance to movement always stays one step ahead of the energy's ability to accelerate the object.

After awhile the increase in inertia vastly outpaces the increase in velocity, to the point that as you get close to c it runs away to infinity.

I am sorry Betweenthepoints but i can understand what you ask but just not put it into words so well. You are asking the reasons behind why these things happen and like everyone else has told you already They just do, it's a design of the universe. Perhaps it would be more clearer if we had a better understanding of gravity on a quantum level and all the 4 forces unified in one superforce. It seems reading alone won't help you, you maybe more of a visual person. Watch some documentries on this, it certainly made a world of difference for me in understanding theories like the string thory and such. I, much better understood gravity after seeing the visual explanations behind it.

The quantum world is extremely crazy, our current english language isn't design to deal with so i really recommend visual aid rather than words.

Janus, thanks. At least that has some of what I actually expect: the reason behind the problem why it is hard to give mass energy to move that fast. Though I wonder why the 'limit speed' is 'chosen' to be the speed of light, not other....

Originally posted by curioucity
Janus, thanks. At least that has some of what I actually expect: the reason behind the problem why it is hard to give mass energy to move that fast. Though I wonder why the 'limit speed' is 'chosen' to be the speed of light, not other....

Because the physical constants that "control" the speed of light have the values they have and don't change with velocity, causing the Speed of light to be fixed. These constants set the maximum speed limit, and light just travels at it.

Why these constants have these particular values, no one knows.

Symmetry, Universe must, at all times, have perfect symmetery. That is why certain things increase and certain decrese during reactions. Law and order must be perserved.

sarge,
did you mean an increase of speed must be countered by the decrease of acceleration? Sorry if that's wrong...
Anyway, I feel like I'm contradicting myself often when it comes to comparing this thread and the <u>light sphere</u> thread in Phy&Math. Don't ask me why, I've thought of some theories which seem to contradict each other.....

Not exactly. Symmetery is a sort of a confusing concept to grasp at first.

There's already been an experiment where they were able to move light faster than the speed of light (might've been lasers)

They had to do it under very specialized conditions (dont remember what they were)

It seemed to them that the light was coming out before it even went in which is pretty cool.

Things can move faster than light, but not in the direct way of applying engines, and trying to move faster and faster because it would just take too long.

Let's get into space first and then figure out how to travel faster ok?

ya, I know, Faith... one thread even discussed that. Besides the experiment was to manipulate wave to act differently; it didn't use matter as the object of experiment.

Can anyone tell me in miles how fast is light.

186,000/sec or 669,600,000/hr

Originally posted by curioucity
ya, I know, Faith... one thread even discussed that. Besides the experiment was to manipulate wave to act differently; it didn't use matter as the object of experiment.

Exactly, anything with no mass can theoretically travel fster than light.

Exactly, anything with no mass can theoretically travel fster than light.

And what theory would that be, John?

I know tachyons are just theoretical, but aren't they particles (with mass) that travel faster than light?

If so, how is this explained?

Originally posted by ic0n612
I know tachyons are just theoretical, but aren't they particles (with mass) that travel faster than light?

If so, how is this explained? IIRC, they have imaginary mass.

Originally posted by ic0n612
I know tachyons are just theoretical, but aren't they particles (with mass) that travel faster than light?

If so, how is this explained?

Aren't Tachyons a byproduct in the string theory?

(Q)


And what theory would that be, John?

I remember reading the same thing. Anything without mass could, theoratically, travel faster than light.

What is the story on this?

Originally posted by sargentlard
Aren't Tachyons a byproduct in the string theory?

(Q)



I remember reading the same thing. Anything without mass could, theoratically, travel faster than light.

What is the story on this?

Patterns can. I think that's what they ment.

Originally posted by (Q)
Exactly, anything with no mass can theoretically travel fster than light.

And what theory would that be, John?

Does not relativity itself imply that massless objects can travel faster than light? Not sure if it was Einstein himself that believed it though, or somebody in years later that figured it out. It has now of courses been proven that light itself can go faster than c (which I hate calling the speed of light).

John

The postulates of relativity are:

"The speed of light c is a universal constant, the same in any inertial frame".

"The laws of physics are the same in any inertial frame, regardless of position or velocity".

I don't see anything that would lead one to assert that massless objects can travel faster than light.

Can you offer an explanation based on these postulates?

Without getting into things like wave/particle duality and such.....don't photons, being particles, have mass?

Originally posted by Halcyon
Without getting into things like wave/particle duality and such.....don't photons, being particles, have mass?

Particle behavior doesn't mean there is mass.

Gotcha.

Now here's a question, which actually has been brought up to surface in a thread, but the thread itself messed up. So here it goes:
When a matter goes fast enough to approach speed of light, according to Lorentz it will shrink. In which direction would this shrinking occur? I mean like when a log goes at speed close to c with both of its points pointing to the same direction, would it be either:
1) The rear point somehow 'moved' to the front
2) The front point somehow 'moved' to the rear
3) Both points moved to the center of gravity of the log
?

Originally posted by (Q)
John

The postulates of relativity are:

"The speed of light c is a universal constant, the same in any inertial frame".

"The laws of physics are the same in any inertial frame, regardless of position or velocity".

I don't see anything that would lead one to assert that massless objects can travel faster than light.

Can you offer an explanation based on these postulates?

Notice I said relativity IMPLIES that, I didn't say it stated it and I certainly didn't say it was a postulate of Einsteins! Remember I said that Einstein himself may not have believed it.
Basically I am saying that relativity doesn't contradict particles travelling faster than c or in other words they are 'allowed' to do so according to relativity. Is that ok ?

Originally posted by curioucity
Now here's a question, which actually has been brought up to surface in a thread, but the thread itself messed up. So here it goes:
When a matter goes fast enough to approach speed of light, according to Lorentz it will shrink. In which direction would this shrinking occur? I mean like when a log goes at speed close to c with both of its points pointing to the same direction, would it be either:
1) The rear point somehow 'moved' to the front
2) The front point somehow 'moved' to the rear
3) Both points moved to the center of gravity of the log
?

I would have thought 3)