Einstein wrong

[CPL.Luke]

photons do have mass e/c^2=m anything that has energy has mass

[CPL.Luke]

but if the speed of light was much higher than it is now that means there were fewer particles at the big bang. if it was several orders of magnittude higher then there would be several orders of magnitude fewer particles in the universe as 1 gram of matter would be equal far more energy than it is now thus less mass and everything because there should be the same amount of energy in the universe today as there was way back at the big bang

 

my understanding of the theory is that light was at an extreme vleocity ie. c^100 ish kind of speed.

 

so if we take that value with 1 gram of matter +1 gram of antimatter we get some very high frequency light. Which would make me wonder where this super high frequency light is today

[Severian]

photons do have mass e/c^2=m anything that has energy has mass

 

No they don't!! Go to the bottom of the class!

[ed84c]

Photons have no rest mass, which is the m quoted in E=MC^2G where g= Sqrt 1-V^2/C^2, they DO have mass whilst moving as E=MC^2 tells us, which is worked out using E=hf

[SubJunk]

that's what they said about neutrinos too and now it's been found they have rest mass

[ed84c]

and theyve also found they travel lower than C

[Ophiolite]

and theyve also found they travel lower than C

I'm feeling lazy today and can't be bothered to go check for a reference to this. Do you have one handy? Also can you (or anyone else) confirm that the neutrino mass referred to by SubJunk is what explains the apparent shortfall in neutrino production by the sun.

Thank you in advance for doing Ophiolite's thinking for him on an off day.

[ed84c]

here you go http://www.newton.dep.anl.gov/askasci/phy99/phy99x18.htm

[[Tycho?]]

photons do have mass e/c^2=m anything that has energy has mass

 

Nope.

[ed84c]

photons have mass but not RESTMASS, e=mc^2, and E=Hf

[J'Dona]

The E in E = mc² and the E in E = hf aren't necessarily the same thing.

 

In E = mc², the energy is the equivalent energy that would be produced by the mass m when you, say, completely annihilate it with antimatter. It's not saying that "anything that has energy has mass". It's saying that mass can be considered a form of energy (hence equivalence).

 

If all energy has mass by the formula E = mc², then it follows that the amount of mass in the universe would always be constant (since the amount of energy is always constant). In that case, why would the products of a nuclear reaction have less mass than the reactants did? The energy is the same, so why not the mass?

 

Besides, if photons had no rest mass, how could they possibly have mass when they're moving (particularly when they always travel at c and the concept of rest mass is meaningless)? The increase of mass with speed doesn't apply to something that has zero rest mass to increase, by any factor.

[swansont]

photons do have mass e/c^2=m anything that has energy has mass

 

When physicists discuss mass, they mean rest mass.

 

What you're using is "relativistic mass" which isn't used because it confuses the issue. But it's used a lot by some who know only a little physics. They are largely the same ones who don't know the difference between speed and velocity, who think that you can't accelerate unless you change your speed, and use weight when they mean mass.

 

Photons are massless.

[swansont]

photons have mass but not RESTMASS, e=mc^2, and E=Hf

 

Actually E = mc² + p²c²

 

(and Planck's constant is h, not H.)

[ed84c]

I think swansont may have concluded the thread in one , by the way what is p in p^2+c^2

[CPL.Luke]

so they have no rest mass its irrelevant

 

a photon can never be at rest there for it doesn't matter

 

they have mass because they are always moving at c and thus they will exert a gravitational force and will be effected by a gravitational force.

 

if this were not true light would bend while moving through a gravitational field

[SubJunk]

ed84c, the last time I checked (4 days ago I admit) no one had proved that neutrinos travel slower than C. What you may be referring to is one of the possible conclusions that the new findings cause us to come to, which are either:

a) e=mc^2 doesn't apply to neutrinos

b) neutrinos travel slightly slower than C

Four days ago neither was proven to my knowledge. Could you post sources?

[CPL.Luke]

the products of a nuclear reaction would have less mass because you can only weigh the rest mass of the products.

 

you can not weigh something that won't congele and hold still on a balance. it would be like trying to weigh an electron (its impossible to do directly)

 

I said that it had mass not weight

[J'Dona]

CPL.Luke, I think you're thinking about Newtonian gravity there, not relativity or the properties of spacetime, which are rather a bit more clever than common sense.

 

If something had no rest mass, it would have no mass at all at any speed, regardless of whether or not the thing in question can ever be at rest. You can't really say that "they have mass because they are always moving at c", since the two are unrelated, and also because relativity explicitly shows that if an object travelling at c had mass, then that mass would probably be infinite.

 

If you didn't know that, you may wish to do more research before posting a response.

[ed84c]

i gave a source regarding neutrinos speed earlier

[Severian]

Actually E = mc² + p²c²

 

(and Planck's constant is h' date=' not H.)[/quote']

 

I think we should have some sort of macro running, that whenever someone types in E=mc², it produces a reply saying:

 

NOOO!!! It's E² = mc² + p²c²

 

[CPL.Luke]

http://en.wikipedia.org/wiki/Tachyon

 

an article on a superluminal particle that may have a real mass

 

my understanding of relativity is that if a particle were to reach light speed it would take an infinite amount of energy. however (newton) if a particle took infinite energy to accelerate to a certain speed it would also take infinite energy to decelerate it. thus all things moving slower than the speed of light will stay slower than the speed of light, a particle moving at the speed of light will stay moving at the speed of light (einstein said this).

 

if a particle had no mass how would it be effected by gravity, I know that GR states that space is warped by mass so, I do know a good amount of the concepts just not the math. If someone could enlighten me to this It would be very much appreciated.

 

 

 

Swansont can you say what p stands for in that equation?

[swansont]

p is momentum.

 

The momentum of a photon is E/c, and that has been verified many, many times by virtue of the fact that laser cooling works.

[CPL.Luke]

swansont that makes that equation no longer work

 

As energy for a photon would look like this

 

E=mc^2+(E/c)^2 x c^2

 

thus energy would be greater than the photons energy, which is a contradiction

 

correct me if I am misunderstanding what you said before

[swansont]

swansont that makes that equation no longer work

 

As energy for a photon would look like this

 

E=mc^2+(E/c)^2 x c^2

 

thus energy would be greater than the photons energy' date=' which is a contradiction

 

correct me if I am misunderstanding what you said before[/quote']

 

THE MASS OF A PHOTON IS ZERO

[CPL.Luke]

its just that you stated e/c when I asked you what p meant so I figured that you could plug that in for p

 

wich just looking at the way I set it up if a photon had a mass of zero you still have

 

E=(E/c)^2c^2

 

giving us the same problem that I stated before E= to a value greater than E

 

for instance

 

if e were 2

 

2=(2/186000)^2(186000)^2

2=(1.075268817e-10)(186000^2)

2=4

 

if I screwed up somewhere please correct me