1

Physics, Astronomy & Cosmology / Re: Does gravity increase relativistic mass?

« on: 29/03/2017 13:31:32 »

Wrong, it is the integral of momentum with respect to velocity. There I've written it in big so you can absorb the information. Speed is a scalar and not a vector so you wouldn't end up with a scalar but a vector. Energy is a scalar. Schoolboy error John. Still, you can write it in big for cut and paste later. Despite yourself you may actually learn some physics yet.

It's speed Jeffrey. You don't end up with negative kinetic energy. Energy is a scalar. Cannonballs do not have less than zero kinetic energy.

Now, do you concede that conservation of energy applies and gravity converts potential energy into kinetic energy and so the relativistic mass of the brick does not increase? Or are you going to persist in promoting bad science? 

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Physics, Astronomy & Cosmology / Re: Does gravity increase relativistic mass?

« on: 28/03/2017 19:53:06 »

...Does the force of gravity increase in magnitude simply because the relativistic mass is increasing? ...

It isn't increasing. Conservation of energy applies. The total energy of the falling brick doesn't change. Gravity merely converts potential energy into kinetic energy.

Right John I will give you some hints. Simply fill in the question marks. The integral of ? with respect to ? is kinetic energy.

The integral of momentum with respect to speed. Please don't try to distract from your errors with trivia.

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Physics, Astronomy & Cosmology / Re: Does gravity increase relativistic mass?

« on: 27/03/2017 22:37:19 »

Are you afraid of calculus then? Since you dodged the question.

Not at all. I just wanted you to focus on the mass deficit. I take it you accept that now?

Yes, please do show me the stack exchange link. Meanwhile the factor of a half is present in KE=½mv² because energy equates to force x distance. Think of a gedanken cannonball in space. It's moving at 100m/s and you apply a constant braking force to stop it in ten seconds. It moves a greater distance in the first second than in the last, and you need an integral to calculate the total distance. Momentum however equates to force x time, and you're applying the force for the same time in the first second as in the last, so there's no integral. I should add that energy and momentum are not two separate things, they're two sides of the same coin, called energy-momentum. You cannot take away that cannonball's kinetic energy without taking away its momentum. 

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Physics, Astronomy & Cosmology / Re: Does gravity increase relativistic mass?

« on: 27/03/2017 22:08:47 »

You do realise that rest mass is invariant don't you?

It isn't invariant. That's why there's a mass deficit. See the Wikipedia binding energy article: "When nucleons bind together to form a nucleus, they must lose a small amount of mass, i.e., there is a change in mass, in order to stay bound. This mass change must be released as various types of photon or other particle energy as above, according to the relation E = mc². Thus, after binding energy has been removed, binding energy = mass change × c²". Whilst you might read about "invariant mass", I'm afraid the phrase is rather misleading. Invariant mass is said to be the same thing as rest mass, but rest mass varies. 

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Physics, Astronomy & Cosmology / Re: Does gravity increase relativistic mass?

« on: 27/03/2017 19:23:29 »

So you think that 'internal' kinetic energy is converted into 'external' kinetic energy. So how do you explain this 'internal' kinetic energy? What is it binding together?

Itself. The E=hf photon is kinetic energy, and you can convert two gamma photons into an electron and a positron in gamma-gamma pair production. See two-photon physics on Wikipedia. As for the exact mechanism I can't give you a peer-reviewed reference I'm afraid. But I suspect it's to do with displacement current.

Also how far does an object have to fall in order to lose all its rest mass and magically transform into a photon?

It can't lose all its rest mass, it can only lose half, because E=mc² and KE=½mv². 

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Physics, Astronomy & Cosmology / Re: Does gravity increase relativistic mass?

« on: 27/03/2017 13:20:03 »

I've told you already. See Einstein's E=mc² paper. A radiating body loses mass because mass-energy is internal kinetic energy. This is demonstrated in extremis by electron-positron annihilation. Each is a radiating body that loses mass. All of it. When you drop an electron, it falls down because some of the internal kinetic energy is converted into external kinetic energy. Then when it hits the ground this external kinetic energy is typically radiated away. The electron mass is then less than what it was. There is a mass deficit. There's also a mass deficit when an electron is attracted to a proton to form a hydrogen atom. The hydrogen atom mass is circa 13.7ev less than the mass of a free proton plus the mass of a free electron. 

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Physics, Astronomy & Cosmology / Re: Does gravity increase relativistic mass?

« on: 27/03/2017 09:12:01 »

Relativistic mass doesn't change? The rest mass is decreasing as the brick falls? And that is just two of your misconceptions. You could always go back to physics.stackexchange.com if you don't like it here. Oh sorry no you can't.

You can read about stack exchange here: Dishonest moderation on Physics Stack Exchange. And you can read about the mass deficit here: Wikipedia: binding energy:

"Classically, a bound system is at a lower energy level than its unbound constituents. Its mass must be less than the total mass of its unbound constituents. For systems with low binding energies, this "lost" mass after binding may be fractionally small. For systems with high binding energies, however, the missing mass may be an easily measurable fraction. This missing mass may be lost during the process of binding as energy in the form of heat or light, with the removed energy corresponding to removed mass through Einstein's equation E = mc²".

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Physics, Astronomy & Cosmology / Re: Does gravity increase relativistic mass?

« on: 24/03/2017 16:49:22 »

BTW John I'm intentionally ignoring the rubbish you typed in response to the first question. Just in case you thought otherwise.

Your response is abusive and ignorant, and it brings Naked Scientists into disrepute. My answer contained appropriate references, and was correct.

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Physics, Astronomy & Cosmology / Re: Does gravity increase relativistic mass?

« on: 23/03/2017 13:55:21 »

If we have a particle freely falling in a gravitational field would it experience an increase in relativistic mass as it accelerates? If not why not?

No, because of conservation of energy, and because gravity is not a force in the Newtonian sense.  When you drop a brick, gravity converts potential energy into kinetic energy. Then when the brick hits the ground the kinetic energy is dissipated, and you're left with a mass deficit. The point to note here is that the potential energy was not stored in the gravitational field, it was stored in the brick, as mass-energy. This mass-energy is actually internal kinetic energy, which is why a radiating body loses mass. See Einstein's E=mc² paper. So when the brick is falling all that was happening is that internal kinetic energy is being converted into external kinetic energy. The sum total energy does not change, so the relativistic mass does not change either, because relativistic mass is really total energy. Instead the rest mass is decreasing as the brick falls.

On a planet with different gravity to earth an object will weigh more if the gravity is at the surface is greater. If we consider this to be a non inertial frame are we justified in attributing this to a gain in relativistic mass. If not why not?

No, because the relativistic mass doesn't change, and because the mass deficit depends on gravitational potential rather than gravitational force.

* conservation of momentum p=mv means the Earth is also affected. But there's no discernible motion of the Earth. The kinetic energy KE=½mv² is not equally shared. The brick gets all bar an infinitesimal portion of the kinetic energy.

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Physics, Astronomy & Cosmology / Re: How would a particle accelerate in a gravitational field?

« on: 18/03/2017 12:28:29 »

If we have a large mass, maybe earth size, in a vacuum with one particle travelling towards it, would it accelerate as fast as say a brick? It should since all masses fall at the same rate. If not why not?

I'm sorry Jeffrey, but your question isn't quite clear. Can you clarify? 

Meanwhile, imagine that I'm in my spacesuit hanging from my gedanken spaceship near an Earth-sized planet. This planet has no atmosphere, but I have a brick in one hand, and an electron in the other. When I let them go, they both fall downwards at the same rate. When they hit the ground the brick kicks up dust and loses kinetic energy, and the electron radiates and loses kinetic energy. The electron then stops radiating. A charged particle does not radiate when its supported in a gravitational field, and it does not radiate when it falls. It only radiates when you stop it falling. Whilst you can find papers saying otherwise, such papers are not in line with the hard scientific evidence, and are wrong.   

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New Theories / Re: Re: Where does the kinetic energy go?

« on: 07/03/2017 22:30:44 »

Likewise polarities repel each other, do you agree with that?

Yes I do. But two bodies attract one another, in line with F = G m₁m₂ / r². The m stands for mass, and the mass of a body is a measure of its energy content, as per Einstein’s E=mc² paper. There are no bodies that contain less than zero energy, just as there are no pencils less than zero inches long. Hence there is no gravitational repulsion. Nor is there any  runaway motion comprised of “a push that repels the positive mass from the negative mass, and a pull that attracts the negative mass”.   

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New Theories / Re: Re: Where does the kinetic energy go?

« on: 07/03/2017 21:58:24 »

Ok John can you list some of the exact solutions to the Einstein field equations that have been found. I can check the answers for you if you like. Seeing as you are such an expert relativist. Oh and not to include the Schwarzschild or Kerr type solutions.

See the scholarpedia article by Malcolm MacCallum. It perhaps gives you what you're looking for:

http://www.scholarpedia.org/article/Exact_solutions_of_Einstein%27s_equations#Some_important_solutions

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New Theories / Re: Re: Where does the kinetic energy go?

« on: 07/03/2017 21:29:37 »

An impossibility, positive v positive = expansion not contraction.

It's not an impossibility, it's general relativity. Check out the stress-energy-momentum tensor  that "that describes the density and flux of energy and momentum in spacetime". It's the energy-density gradient that makes light curve and matter fall down. Also see the Einstein digital papers: "the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy".   

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New Theories / Re: Re: Where does the kinetic energy go?

« on: 07/03/2017 21:05:18 »

Those used copies are nothing to do with me. I can't stop people selling them on Amazon. No new copies have been on sale for about 5 years now.

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New Theories / Re: Re: Where does the kinetic energy go?

« on: 07/03/2017 19:41:59 »

You have to understand that Mr. Duffield has a book to sell and a pet idea to peddle. He has admitted many times that he doesn't actually do physics problems.

I don't have a book to sell or a pet idea to peddle. I'm here to educate and inform with reference to robust physics and so oppose the popscience misinformation that is sadly all too common these days. Einstein made it clear that gravitational field energy is positive, and that this energy has a gravitational effect.

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New Theories / Re: Re: Does a photon have inertia?

« on: 07/03/2017 17:22:50 »

The main sections of this forum General Science, Non Life Sciences, and Life Sciences are reserved for currently accepted theory. Any new theory, or variation or reinterpretation of an accepted theory, should be posted in New Theories or Just Chat. See https://www.thenakedscientists.com/forum/index.php?topic=66954.0 Persistent offenders can face a ban.

I haven't posted anything incorrect. Compare my answer with pmb's here: "No. The speed of a photon changes with gravitational potential. This is a well known fact in GR and was one of the first results Einstein derived in his papers on GR."

PhysBang is being malicious and dishonest I'm afraid. He doesn't contribute positively to forums like this. I don't talk on forums like this for personal gain. I do so to educate. 

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New Theories / Re: Re: Does a photon have inertia?

« on: 06/03/2017 19:17:59 »

Why had this post been moved to new theories? 

How can I complain about this?

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New Theories / Re: What is the difference between gravity potential, and gravity potential energy?

« on: 05/03/2017 13:08:40 »

Thank you John.  Btw, I am aware that if one uses duration of a GR time dilated second to calculate the speed of light via, then it could be said that light slows down closer to mass, as a time variant, not a speed variant.

Einstein talked about the speed varying, as did Irwin Shapiro:

 

This is of course interesting to me, but despite your description of momentum, I am no closer to an explanation of 'why' p is being used in the maths.

I read somewhere that it's p for petere, which is the latin for impetus.

...my question arising from Janus's answer is very specific, and having had the title question answered by Janus, the question I am asking now is specifically as I state and it is that and nothing else that I require an answer to, at this time.

I had hoped I'd answered your question, in that momentum is a time-based measure of resistance to change-in-motion.

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Physics, Astronomy & Cosmology / Re: Does a photon have inertia?

« on: 04/03/2017 19:15:23 »

That is a bold and sweeping statement. Can you justify it in your own words?

It isn't a bold and sweeping statement, it's just physics. Gian Francesco Guidice is a respected CERN physicist with over a hundred papers to his name.

Since by inference you profess to understand it. Will I get a reply?

Why don't you start a thread asking some question or making some proposal, and I'll tell you what I can.

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New Theories / Re: What is the difference between gravity potential, and gravity potential energy?

« on: 04/03/2017 18:51:28 »

Perhaps I can assist?
 

So Janus - In the case of light falling towards body M, we can understand that as the photons are the equal of each other at each coordinate within the gravity potential well, and all travelling at the same speed, ie: c, that all photons are affected equally.

All photons are affected equally, but rather counter-intuitively, the descending photon slows down. In similar vein, the ascending photon speeds up. Check out this PhysicsFAQ article  by relativists Don Koks: Is The Speed of Light Everywhere the Same? The answer is no. See this:

So consider the question: "Can we say that light confined to the vicinity of the ceiling of this room is travelling faster than light confined to the vicinity of the floor?".  For simplicity, let's take Earth as not rotating, because that complicates the question!  The answer is then that (1) an observer stationed on the ceiling measures the light on the ceiling to be travelling with speed c, (2) an observer stationed on the floor measures the light on the floor to be travelling at c, but (3) within the bounds of how well the speed can be defined (discussed below, in the General Relativity section), a "global" observer can say that ceiling light does travel faster than floor light.

And that when m's of differing mass value are free falling towards M, the gravity potential, and resulting gravity potential energy decrease for m in free fall is going to be differing for m's of differing values of mass.

The gravitational potential energy is converted into kinetic energy. Having a mass of a different size is only like having a different number of unit masses.

I know you cannot explain why this happens because it is not currently known why all values of m accelerate at the same rate in free fall.

I didn't think there was any mystery to that.

But...  the mass or relativistic mass value for m and light, respectively, are used in calculation to describe momentum, or p in the maths.

Relativistic mass is a measure of energy.

What exactly is the physical description of momentum?

A time-based measure of resistance to change-in-motion. Kinetic energy is a distance-based measure. Think of a cannonball in space moving at 1000m/s. When you apply a constant braking force you bring the cannonball to a halt in x metres, which is your kinetic energy measure, and y seconds, which is your momentum measure. Divide by c which is distance over time to go from one to the other. People tend to say a cannonball has kinetic energy and momentum, but you can't remove one without the other. Because they're two aspects of the same thing, called energy-momentum.