[charles1948 (OP)]

Is it wise to appeal to Newton's "shell theory"?  Newton was a 17th century scientist. He was undoubtedly a genius.

But he didn't have access to the knowledge we have in the  21st century.  Such knowledge includes the existence of the "Strong Force" which operates between the protons in the nucleus of atoms.

Isn't this "Strong Force" a "repulsive" one,  which lets protons overcome the inner force of Gravity.
And so remain as individual particles. Instead of being crushed together by Gravity into a homogenous lump.

Newton didn't know anything about this. His theory dealt only with the outer "attractive" effects of matter on a large scale. Such as between big bodies, like planets. He knew nothing about atoms, and their inner workings.

So why rely on Newton when asking questions about a possible repulsive force at the core of a body?

[charles1948 (OP)]

Thanks Kryptid.  On the subject of Newton, don't you think he'd have a fit, if he received (via time-warp) a book on modern physics.

[Kryptid]

On the subject of Newton, don't you think he'd have a fit, if he received (via time-warp) a book on modern physics.

I guess that depends on what you mean by "fit". No doubt he'd be shocked and amazed at some of our discoveries.

[charles1948 (OP)]

Yes, and probably been appalled . He might've said: "Go on Diamond, knock the candle over again and burn the book".

Then given up physics and concentrated on his alchemical and biblical studies. 

[Kryptid]

Is there a point you are getting at?

[charles1948 (OP)]

Is there a point you are getting at?

Not really, I just get pleasure from conversing with you, and other scientifically-minded people on this forum.

It's such a relief from trying to converse with my partner, who's a nice man, but isn't interested in science, and just watches vacuous TV all day.

[Kryptid]

Ah, all right. Sorry if that sounded snappy. I thought you may have been trying to imply that we couldn't trust Newton's physics.

[Kryptid]

It would be nice if his ideas extended to the Universe as a whole. That would make sense.

Perhaps they do, and we are being misled by attaching an undue significance to the "speed of light".

Relativity is pretty well supported by the evidence. Regardless, I think you'd need to start a new thread if you want to go down this route.

[charles1948 (OP)]

"Relativity"  theory has become too firmly entrenched to be challenged in the 21st Century.

Just as "Geocentric" theory was historically entrenched in the 16th Century.   If you challenged it,  you got stuffed.

Doesn't History repeat  itself, even in Science?

[Kryptid]

"Relativity"  theory has become too firmly entrenched to be challenged in the 21st Century.

It's "entrenched" because it has massive experimental support. If we found strong evidence of it being wrong, it would be rejected as being an incomplete description of reality. We already know that it is incomplete because it doesn't mix well with quantum mechanics.

If you challenged it,  you got stuffed.

The "challenges" to it are based on misunderstandings of it. Misunderstandings of how relativity works are legion. I get it wrong myself from time to time. If one is going to contest relativity, they'd better get the facts right before they even try.

But like I said, if you are going to go on about this, start a new thread. This is my last off-topic reply to this matter.

[charles1948 (OP)]

I'm not going to start a new thread, because we've had enough already on this issue.  The basic fact is this:

The core of all bodies in the Universe, must contain a source of repulsive gravity.  Like the OP suggests

Otherwise, everything in the Universe would shrink into a dimensionless point, and blink out of existence,

The fact that this hasn't happened, and that the Universe continues to exist,  must mean that it contains a repulsive force.

This seems so obvious.  Why are posters trying to dispute it?

[Colin2B]

I'm not going to start a new thread,

Ok, we’ll do it for you

[Bored chemist]

This seems so obvious.

It is obvious,

Why are posters trying to dispute it?

It is wrong- not least for the reason I gave earlier.
If there was something which was repelled by mass the one place you would not find it would be in the middle of a lot of mass- like in a star, because it would be repelled away from there.

Otherwise, everything in the Universe would shrink into a dimensionless point, and blink out of existence,

Unless something else stopped it- which it generally does..
https://en.wikipedia.org/wiki/Electron_degeneracy_pressure

So, it's obvious that they will collapse- unless you understand why they don't.

[Kryptid]

The core of all bodies in the Universe, must contain a source of repulsive gravity.

There is a repulsive force, but it isn't related to gravity. In most common forms of matter familiar to us, it's the repulsion between the electrons that surround atoms. In a gas, there is an additional "repulsive" force that arises from its internal pressure (which comes from the kinetic energy of the gas atoms/molecules). That is the force that keeps the stars from collapsing.

[CrazyScientist]

There might be evidences, that can be tested experimentally and suggest that gravity can act as a replsive force:

http://www.ccsenet.org/journal/index.php/apr/article/view/57519

Plasma arc bends upwards even in partial vacuum. Repulsive force of gravity can be expressed here as "negative weight". I will discuss this subject further in a separate thread in the near future...