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Physics, Astronomy & Cosmology / Re: Can each dimension of space be represented as a vector?

« on: 07/06/2019 02:10:57 »

Can space be represented as a “structure” of three “dimension vectors” ?

I agree. To put a fine point on it the dimension of a manifold (aka "space") is how many numbers i takes to uniquely define a point in a space. That doesn't mean that it takes three distances. Consider spherical coordinates. One number measures a distance from the origin while two represent angles.

Length scales are associated with meters.

Not always true here in the US where things are often measured in miles, etc.

Kerr-Newman metric....Schwarzschild metric...

These metrics are associated with black holes.

The Schwarzschild metric is used for more than that. It describes stars and planets too.

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Physics, Astronomy & Cosmology / Re: What would happen if a human freezes to absolute zero temperature?

« on: 07/06/2019 01:59:41 »

for men the shrinkage would be horrible ...ahhhhhhh!!!!.

But seriously, nothing can reach absolute zero 0 K.

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Physics, Astronomy & Cosmology / Re: What are the mechanics of Time dilation - how and why does it work?

« on: 07/06/2019 01:57:23 »

I created a webpage to provide the derivation. See: http://www.newenglandphysics.org/physics_world/sr/time_dilation.htm

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Physics, Astronomy & Cosmology / Re: What causes space/time dilation?

« on: 07/06/2019 01:53:08 »

I was trying to understand why it is that time slows down as you approach the speed of light and read that it's something to do with space contracting and distorting time.

It's called time dilation, not spacetime dilation. But yes, that is essentially correct. To be more correct means the following derivation of the physics behind it. I created a webpage deriving it at: http://www.newenglandphysics.org/physics_world/sr/time_dilation.htm

As the derivation starts off it says

The phenomena of time dilation can be derived from the two postulates of special relativity, namely

(1) The Principle of Relativity - The laws of physics are the same in all inertial frames of reference

(2) The Light Postulate - The speed of light in an inertial frame of reference is independent of the source

I don't answer questions about that fluid thing since it'd be classified as a new theory which is another sub forum here and I don't like posting in that forum. But I will say that it sounds like an ether theory and those have been discredited for the most part.

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Physics, Astronomy & Cosmology / Re: Is earth moving at close to the speed of light?

« on: 25/04/2019 08:59:42 »

Since motion is relative then in some frames of reference we can be considered to be moving close to the speed of light. Are we actually moving at close to the speed of light?

The question is incomplete. You need to ask "are we moving near the speed of light in as measured in frame S." where S is specified by the person asking the question. In our frame (sitting on earth) the answer is no.

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Physics, Astronomy & Cosmology / Re: Would dark energy cause negative time dilation?

« on: 22/04/2019 00:06:46 »

If gravity causes time dilation would dark energy cause the opposite effect?

No.

Dark energy is the term used to describe what causes with accelerating expansion of the universe.

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Physics, Astronomy & Cosmology / Re: Would dark energy cause negative time dilation?

« on: 21/04/2019 00:54:06 »

No, I mean a really uniform gravitational field, one that causes no acceleration at all because mass is uniformly distributed everywhere, as is dark energy.

Neither of those things are true. A "really uniform gravitational field" causes matter to accelerate anywhere that its placed in the field (at least above the Rindler horizon.

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General Science / Re: Would legalization of Marijuana increase general health?

« on: 10/04/2019 18:45:36 »

I'm all for it. I live in Massachusetts where its medical use is legal and its legal for recreational use. I have chronic pain, an anxiety disorder and insomnia which should be helped by using pot products.

I have no problems with allowing medical uses of cannabis such as alleviating the symptoms of chemotherapy (eg nausea & weight loss), if it can be shown to be effective.

• Short-Term: Impaired alertness and coordination (ie no driving, operating machines or serving customers)
  
• Long-term: Lung Cancer, pulmonary & cardiovascular damage (similar to tobacco), decrease in short-term memory and feelings of paranoia or anxiety

Its use for chronic pain is helped buy using it since opiates are nearly impossible to get nowadays. A few years ago the pain was severe to extreme from hours to days on end. It was like being tortured. I don't knw how well it will work though.

Today's my first day going to buy some at a medical marijuana pharmacy. Wish me luck! [/list]

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New Theories / Re: Can a photon be visualized ?

« on: 10/04/2019 18:31:02 »

Thanks I never thought of it this way.

The derivation is on my website at http://www.newenglandphysics.org/physics_world/gr/c_in_gfield.htm
The paper I mentioned is Fourth Test of General Relativity[/b] by Irwin S, Physical Review Letters, Vol. 13, No. 26, Dec 28, 1964

The author writes

Because , according to the general theory, the speed of a light wave depends on the strength of the gravitational along its path, ...

You might be able to find that paper online at https://booksc.xyz/

Would I be correct in thinking c is still measured as constant, wherever it is measured, because the ruler has shrunk and time as slowed?

No. That's only the why it happens.

Does this also mean light is faster than c as it moves towards a gravitational source, ..

No.

if this is so what happens at event horizons of BH's, do things suddenly disapear as they enter a BH or does time slow, and rulers shrink meaning they are stuck in the horizon??

Those are the reasons behind why light never reaches event horizon.

I urge you to get a GR book and study this phenomena. My website will give you a place to  start. I'm  always here of course.

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New Theories / Re: Can a photon be visualized ?

« on: 10/04/2019 12:39:19 »

Can you confirm c is the same for everyone under GR and SR relatively speaking. I am not aware of any experiments indicating c is variable in a gravitational field.

Experiments in the 1960's by Irwin Shapiro confirmed what Einstein predicted, i.e. that c is variable in a non-inertial frame, i.e. a gravitational field.

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New Theories / Re: Can a photon be visualized ?

« on: 10/04/2019 00:30:28 »

Unlike Maxwell, the particle model doesn't predict the speed of light, nor that it is constant for all photons, unless you accept the conclusion of general relativity, i.e. that massless particles must all travel at c.

I said that not to argue that the standard model predicts c but that your argument was fallacious.

BTW - its SR that c is invariant, nor GR. In GR the speed of light varies with the gravitational potential. Einstein showed this in 1907 and 1911.

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Physics, Astronomy & Cosmology / Re: Why negative gravitational energy?

« on: 09/04/2019 23:35:09 »

Have a read of this.
https://www.s-cool.co.uk/a-level/physics/gravitational-potential-energy/revise-it/gravitational-potential
See how potential is simply a negative scalar. Basically E/m where E is energy and m is mass. Read it through a few times.

Bill asked about potential energy, not potential. U = potential energy whereas U/m = V = potential. Sometimes U is called just 'potential.'

Note: E is usually used to refer to total energy, not potential energy.

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Physics, Astronomy & Cosmology / Re: Why negative gravitational energy?

« on: 09/04/2019 23:31:55 »

The potential is U = -GMm/r just like I said earlier and Janus confirms. Suppose the kinetic energy is positive in the beginning at a large distance from r = 0. Then the potential is negative and the kinetic energy is positive while the total mechanical energy, E, is positive. The closer it gets to r = 0 the greater the kinetic energy and the less U is where E = U+ K = constant.

Hold on! "Suppose the ke is positive in the beginning"? No, I'm releasing a small object m from rest at distance r from the barycentre of m and M. The ke of m is initially zero, and increases as it moves towards M, so its initial pe must be positive.

If you're releasing a particle "from rest" then there is a choice of what to set U to at that point. There always is. If you add a constant to U then the potential will still be negative somewhere. That follows from the fact that F = -grad(U + constant) = -grad U. I could easily set U such that U(r) = 0 rather than U(inf) = 0.

I gotta say that I'm suprised you don't know all of this. You're much better at physics than the comments in this thread,

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Physics, Astronomy & Cosmology / Re: Why negative gravitational energy?

« on: 08/04/2019 23:58:07 »

Now you've got me worried. I have a mass m at a large distance from M. As it hurtles earthwards it exchanges mgh for ½mv², which is always positive, so its potential energy must have been positive before it started moving.

The potential is U = -GMm/r just like I said earlier and Janus confirms. Suppose the kinetic energy is positive in the beginning at a large distance from r = 0. Then the potential is negative and the kinetic energy is positive while the total mechanical energy, E, is positive. The closer it gets to r = 0 the greater the kinetic energy and the less U is where E = U+ K = constant.

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Physics, Astronomy & Cosmology / Re: What is an "event" ?

« on: 08/04/2019 20:26:11 »

PmbPhy#60;
How can you assign a coordinate to empty space, i.e. without a reference object? Distance, time, and motion are only relative to a reference frame, in SR.

I don't think you can in practice. Typically a coordinate system is defined by using a reference. But that doesn't mean that space is filled with stuff.

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Physics, Astronomy & Cosmology / Re: Why negative gravitational energy?

« on: 08/04/2019 20:21:53 »

The gravitational potential of a small test mass is defined as zero at infinite distance from a single large attractor, hence negative at the centre of said attractor. Thus the potential energy of a test mass is always positive with respect to the large attractor, and in free fall towards it, the loss of potential energy equals the gain in kinetic energy.

Bill  - Sorry I wasn't able to explain it better. I think you do understand it. Explaining to others is troublesome due to the wide variety of each of the "other" people. To answer your question one has to use math because your question is math oriented and thus about the math of Newtonian gravity itself.

Not so. The potential energy of a particle in such a field is zero having the value U = -GMm/r

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Physics, Astronomy & Cosmology / Re: Why negative gravitational energy?

« on: 08/04/2019 02:19:33 »

https://en.wikipedia.org/wiki/Negative_energy 

“The strength of the gravitational attraction between two objects represents the amount of gravitational energy in the field which attracts them towards each other. When they are infinitely far apart, the gravitational attraction and hence energy approach zero. As two such massive objects move towards each other, the motion accelerates under gravity causing an increase in the positive kinetic energy of the system. At the same time, the gravitational attraction - and hence energy - also increase in magnitude, but the law of energy conservation requires that the net energy of the system not change. This issue can only be resolved if the change in gravitational energy is negative, thus cancelling out the positive change in kinetic energy. Since the gravitational energy is getting stronger, this decrease can only mean that it is negative.”

Why is gravitational energy, rather than kinetic energy, seen as being negative?

It depends on the particular example. In this case the gravitational potential, U, is negative so that -grad U = F. This also holds for a positive source and a negative particle moving in the sources field. There are cases when U is negative in one region and positive in another. An infinitely long line of mass is an example.

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New Theories / Re: Can a photon be visualized ?

« on: 08/04/2019 02:14:34 »

0 spin connotes zero angular momentum

Not true. Angular momentum is the sum of angular momentum associated with angular speed + spin.

sub elementary particles in the space/time fabric are in a ground state

What is a "sub elementary particle"? There's no such thing that I'm aware of. In any case there's no basis to assert that they're in the ground state. That's only possible when a particle is in a potential. And spacetime has little to do with explaining this.

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New Theories / Re: Can a photon be visualized ?

« on: 08/04/2019 01:16:34 »

Please correct where I am wrong.

Maxwells equations describe the classical view of electromagnetic waves.

A single photon can be viewed as a quantum particle.

Its not possible to state whether a photon is a particle or a wave unless you state how its observed. That's the essence of the wave-particle duality.

Note that the Schrodinger equation only holds for non-relativistic particles and photons are relativistic particles.

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New Theories / Re: Can a photon be visualized ?

« on: 08/04/2019 01:13:52 »

The particle model doesn't predict the speed of light in vacuo because there is nothing there to absorb and re-emit particles.

Let a source emit a photon at A and it arrive at B where a detector registers it. The particle model states that the photon is emitted at and absorbed at B. No need to re-emit. And this holds for distances from 1 nm to any number of light years.