The weight of capacitance :-)

electrons.

it

Hey, Fields! You sure have a short attention span! Don't you remember Larkin's claim that charge is NOT conserved ?:-) ...Jim Thompson

It does, the other one does too.

Rick

electrons.

it

Try reading the reference! NEVER use Wikipedia as a primary reference. Wikipedia doesn't!!! Go to the reference they list and see what they say. Wikipedia is more like a magazine article and you should assume something is lost in the translation.

In fact, you don't even need to go to the reference. Just look at the mouseover text for the reference link... Here it is for your purview...

The photon is massless,[Note 2]

The mass of the photon is believed to be exactly zero, based on experiment and theoretical considerations described in the article. Some sources also refer to the relativistic mass concept, which is just the energy scaled to units of mass. For a photon with wavelength ? or energy E, this is h/?c or E/c2. This usage for the term "mass" is no longer common in scientific literature. Further info: What is the mass of a photon?

They say the usage of mass as the equivalent of energy is no longer "common" in the literature, but that doesn't invalidate the concept. Mass has momentum and so do photons.

Rick

More nonsense! IIRC, that was the first manner in which relativity was confirmed by experiment, when light was bent by the mass of the sun.

Rick

But it doesn't logically follow that photons have mass. (Actually, mass doesn't have momentum. Mass has the units of kg, but momentum is kg*m/s)

Photons are not affected by the gravitational force. Equivalent mass is not mass.

electrons.

it

Except that it doesn't. Look it up.

That is caused by relativistic distortion of space, not the effect of gravity on photons. Again, look it up.

Photons don't attract one another.

electrons.

it

You are saying a photon does not have momentum? Wow, there are so many examples of why you are wrong. Can you find a reference that says photons have no momentum? I've already pointed you to one that says it does.

You seem to think gravity is just unilateral. The photons also warp space and attract the black hole or other massive body. You can call it "warping space", but that is gravity by another name.

Rick

lectrons.

empty it

s there

Hmm, OK my 'view' is a bit different.

So I figure that the light, as well as all the other 'stuff' in the universe contributes to the overall energy/mass density. (Mind you, I've never studied GR.)

Maybe the 'light' is only a ppm contribution (or even smaller). But without the 4 degree background radiation I'm guessing the universe would 'weight' less.

George H.

ed text -

Uh, actually, it does logically follow. Mass has momentum when it is moving. p = m * v, so yes, the units of momentum will be kg * m/s.

Actually it is. Photons are affected by gravity just like all other mass. Mass and energy are the same thing. Photons have zero rest mass because it would violate Newtons' as well as Einstein's laws, not to mention a host of others, to accelerate a non-zero rest mass to the speed of light. But the equivalent mass of the photon is affected by all the normal laws of the universe as any other mass.

Like someone else pointed out, if photons don't have mass, why would they be trapped inside a black hole?

Rick

electrons.

it

there

They have momentum but no mass. Look it up.

I did look it up and I showed you the reference where they clearly say photons have relativistic mass. You can't have momentum without mass as momentum is proportional to mass times velocity.

Read the page you link to above. But read the full info, the note 2 mouse-over text is good enough or follow the links from there.

Even you should know better than to trust the text on a Wikipedia page that is edited by anyone with a computer.

Rick

electrons.

it

electrons.

it

there

Well it isn't always conserved. What you misplace it? Are you suggesting that I could ALWAYS find my keys if I just put a small charge on them?

I know someone who is a professional conservator and she never seems to conserve charge.

Rick

a mole of photons does have mass, well, it has weight.

Put them in a perfectly reflective box and gravity will curve the paths the phontos take so that they curve downwards, this means they will strike the bottom of the box harder and more often than the top. this will make the box seem heavier than if it was empty.

On a sunny day (Tue, 16 Oct 2012 13:09:39 -0500) it happened JOF wrote in :

Been thinking, I have these special shoes, you walk on those in the supermarket and you get charged to several kV and make long sparks (painful to sometimes) to the racks with food.

So I think that when I am charged that way, I weigh more, as I am carrying all those electrons around. After the discharge I should weigh less. Van De Graaf generator?

Shoes are for rent for destructive EMC testing :-)

charged to

Maybe you can install some of those LEDs you've been lighting with candles into the shoes, making them flash while you're walking. You might need a ground strap, but that can't hurt anyhow. Get a little light in the heels!

On a sunny day (Mon, 22 Oct 2012 22:21:13 -0500) it happened JOF wrote in :

charged to

Neons would work better, flashing red at the rear. :-)

I may actually try that....