mass

[sunspot]

If the speed of light is the same in all reference, how can a reference state created by gravity effect energy if it travels at the same speed in all references?

[TimbaLanD]

Energy has everything to do with mass and mass (well energy) has everything to do with gravity.

 

Ok... if this is the case, they why does light has no mass?

[5614]

Ok... if this is the case, they why does light has no mass?

Because when you say "mass" you are referring to the rest mass of the object.

 

Rest mass is the mass of an object when it is not moving.

 

A photon has no rest mass because it always travels at c, it never stops moving, it never rests, so it cannot have a rest mass.

[CanadaAotS]

A photons relative mass is its mass related to energy. This it does have. Since energy bends space-time (creates gravity) mass (a form of energy) also bends space-time.

[TimbaLanD]

Because when you say "mass" you are referring to the rest mass of the object.

 

Rest mass is the mass of an object when it is not moving.

 

A photon has no rest mass because it always travels at c' date=' it never stops moving, it never rests, so it cannot have a rest mass.[/quote']

 

I wonder what powers a photon!! If it has no mass and it’s capable of travelling such distance with such speed, where the h3ll does it get the power from???

 

Are you saying that a moving photon has mass but it has no mass at rest?

[swansont]

I wonder what powers a photon!! If it has no mass and it’s capable of travelling such distance with such speed, where the h3ll does it get the power from???

 

A photon does not need to be "powered" to keep it moving. Think of Newton's first law.

 

Are you saying that a moving photon has mass but it has no mass at rest?

 

Mass is zero. Some of the confusion her probably stems from people using different definitions of mass (i.e using the outdated "relativistic mass" interchangeably with "rest mass" but the two have contradictory definitions)

[TimbaLanD]

A photon does not need to be "powered" to keep it moving. Think of Newton's first law.))

 

As I understand, Mass is the amount of matter that something has in it?? I don’t see how it can change with respect to speed? No matter how fast we travel, out mass remains the same??

 

Light is something that we see with our eyes, so surely it must have matter thus matter = mass. I still don’t understand the fact that light has no mass but it has matter????

[danny8522003]

Think of Einsteins equation e=mc^2, this shows that energy is interchangable with matter. Therefore more energy, more mass.

 

Rest mass gives the mass of an object if it had no energy, i.e. it is at rest. In this way the rest mass of a photon is zero. Using Einsteins we can see that photons have something called relativistic mass. Use hf=mc^2 to find this.

 

Relativistic mass is an outdated term so we simply say that photons have no mass, they are just a 'clump' of energy.

 

Again, using e=mc^2 we can see that as an object gains energy it's relativistic mass increases (hence why objects with mass cannot reach c because of the gain in kinetic energy it possesses as it gets faster).

 

E = mc^2/sqrt(1 - v^2/c^2) shows that when v=c the equation has a 0 as the denominator, any fraction with a 0 at the bottom and a number >0 at the top equals infinity. This is why infinite energy is required to speed objects with rest mass up to c and is therefore impossible. If m = 0 we get a 0 at the top.

[CanadaAotS]

As I understand' date=' Mass is the amount of matter that something has in it?? I don’t see how it can change with respect to speed? No matter how fast we travel, out mass remains the same??

 

Light is something that we see with our eyes, so surely it must have matter thus matter = mass. I still don’t understand the fact that light has no mass but it has matter????[/quote']

 

Nothing "has" matter. It is matter or it is not.

 

Mass is not the amount of matter something has in it... its the total mass of protons, neutrons, electrons and other particles that travel less then the speed of light.

 

photons are massless as are any particles travelling at the speed of light (gravitons included), being massless they do not need energy to move (besides the fact that they are energy pretty much).

 

Although this is pretty much speculation, there are supposed to be particles that always travel faster then the speed of light, travel backwards through time and have imaginary values of mass (square root of negative 2 as example).

 

and we don't exactly see light either. seeing is produced by photons of certain wavelengths hitting our retina's which stimulate signals sent to the brain that are then decoded into images.

[5614]

Although this is pretty much speculation, there are supposed to be particles that always travel faster then the speed of light, travel backwards through time and have imaginary values of mass (square root of negative 2 as example).

Yeah, "supposedly" as in we've never detected them, there's no solid proof for the and many (in fact the majority) of physicists would say that they do NOT exist.

 

and we don't exactly see light either. seeing is produced by photons of certain wavelengths hitting our retina's which stimulate signals sent to the brain that are then decoded into images.

We do "see light" and "seeing" is when photons hit our retina... What do you mean?

[Quantoman]

@the geek

 

 

i believe that a photon is the only particle that can be at

two places at once.

[danny8522003]

@the geek

 

 

i believe that a photon is the only particle that can be at

two places at once.

 

Nah i know electrons do it too. Id hazard a guess that every 'elimentary' particle does.

[Severian]

What do you mean by 'at once'? Simultaneity depends on the reference frame. Two events which are simultaneous in a particular reference frame may not be in a different reference frame.

 

So photons (or any other particle) cannot be "in two places at once".

 

(I suspect what you mean is that if you were in the photon's rest frame, all other time intervals between external events would appear infinitely time dilated. But since the photon has no rest frame, the point is moot....)

[CanadaAotS]

Yeah' date=' "supposedly" as in we've never detected them, there's no solid proof for the and many (in fact the majority) of physicists would say that they do NOT exist.

 

We do "see light" and "seeing" is when photons hit our retina... What do you mean? [/quote']

 

I was talking about tachyon's. a number of theory say they could exist, but since we'd never be able to detect, they can be said not to exist.

 

I don't know where I was going about that light thing lol.

[5614]

Yeah I was referring to the light thing when I said "what do you mean".

[TheGeek]

@the geek

 

 

i believe that a photon is the only particle that can be at

two places at once.

 

how do u be at two places at once? isn't that breaking laws of physics and the fabric of life?

[swansont]

how do u be at two places at once? isn't that breaking laws of physics and the fabric of life?

 

Feynman path integrals are taken over all paths, meaning a photon behaves as if it takes all possible paths in its travel.

 

A wave function has a spatial extent, so in essence anything with a wave function that has a reasonable spatial extent is in more than one place at once - until you make a measurement.

[Quantoman]

ya what he^ said....

 

 

__________________

 

free thinkers need debunkers and debunkers need free thinkers

[Klaynos]

Feynman path integrals are taken over all paths' date=' meaning a photon behaves as if it takes all possible paths in its travel.

 

A wave function has a spatial extent, so in essence anything with a wave function that has a reasonable spatial extent is in more than one place at once - until you make a measurement.[/quote']

 

But of course this also applies to electrons and other particles.... So not just photons can be "in two places at once"... Although personally I dislike that terminology :s

[TimbaLanD]

Staying on the subject of mass and energy, as I understand from all the above that mass is proportional to energy? But is energy proportional to mass? In Einstein’s equation E=MC2, did he use “C” because it has “0” mass?

 

Force is a from of energy buy why does it has no mass?

[Royston]

As far as I know, any subject in an equation is proportional to any parts of the sum i.e mass is proportional to energy, C squared is proportional to mass and so on.

 

So if we had a=bcd, a is proportional to b, a is proportional to c and so on.

Einsteins equation is showing that the properties of either energy, mass or the speed of light are intrinsic with each other....very basically.

 

Someone correct me if I'm wrong here, I've only just started rearranging and combining algebraic equations.

[swansont]

Staying on the subject of mass and energy' date=' as I understand from all the above that mass is proportional to energy? But is energy proportional to mass? In Einstein’s equation E=MC2, did he use “C” because it has “0” mass?

 

Force is a from of energy buy why does it has no mass?[/quote']

 

The equation is derived, not just stated. "c" shows up as a result of it being constant in all inertial frames, and the dependence on how physical quantities transform between reference frames.

 

Force is not a form of energy. The question is ill-defined.

[TimbaLanD]

The equation is derived' date=' not just stated. "c" shows up as a result of it being constant in all inertial frames, and the dependence on how physical quantities transform between reference frames.

 

Force is not a form of energy. The question is ill-defined.[/quote']

 

Ok, I understand the equation is derived not stated. Now I understand the use of “C” as it has a constant speed.

 

What I am trying to understand is why mass increases as we speed up?

[Ragib]

Ok' date=' I understand the equation is derived not stated. Now I understand the use of “C” as it has a constant speed.

 

What I am trying to understand is why mass increases as we speed up?[/quote']

Well, You see, Eiensteins Equation, E=MC^2, is explaning the EQIVALENCE of Mass And Energy, mass is just a form of energy, as is kinetic energy and so on.

Now, if you speed up, you add Kinetc Energy, energy of motion. Adding this energy adds an extremely small amount of mass. To calculate the Mass of something moving, theres the relatavistic formula: , where . So you see, other than at high velocities, the difference is unnoticeable. Just basically, you gain mass as you speed up because mass and energy are the same, and you are gaining Kinetic energy.

[TimbaLanD]

So, at high speeds, energy is accumulated hence increasing its mass. This increase in mass has no physical form? I am so confused!!!!!