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What's Up With Gravity And Spacetime Curvature?

general relativity.

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#52 Moronium

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Posted 30 January 2019 - 04:40 AM

Heh, Popeye, that cartoonist expresses my sentiments exactly.



#53 Moronium

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Posted 30 January 2019 - 04:57 AM

I once knew an elderly man who wore spats, a monocle, and affected a limp by walking with a cane.  He spent his time going around to advanced math classes in high schools and enthralled his audiences there by reciting pi, from memory,  to a thousand digits.  They paid rapt attention, only occasionally fidgeting with their slide rules, while listening in wide-eyed amazement.  At the end he would generally get a standing ovation.

 

For some reason, I never found his performances as entertaining as those math geeks did.


Edited by Moronium, 30 January 2019 - 05:49 AM.


#54 Moronium

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Posted 30 January 2019 - 05:33 AM

Math!  Yeah, that's the ticket.  A theory of EVERYTHING, I tells ya!

 

The Dangerous Irrelevance of String Theory

 

Eva Silverstein has a new preprint out, entitled "The Dangerous Irrelevance of String Theory."...

 

...I think the comparison to EM or GR is pretty much absurd. For one thing it’s comparing two completely different things: tests of a particular prediction of a theory (EM or GR) that made lots of other testable, confirmed predictions to the case of string theory, where there are no predictions at all.

 

I don’t think anybody can seriously claim that, 33 years on, we’re closer to a successful string theory unification proposal than we were at the start, back in 1985. I’d argue that the situation is the complete opposite: we have been steadily moving away from such success (and thus entered the realm of failure).

 

 

https://www.math.col...rdpress/?p=9375

 

Many decades and billions of dollars in scarce research funds devoted (unsuccessfully) to the irrelevant pursuit of mathematical "truth," eh?  Have faith though.  Give it another hundred years. Numbers don't lie!!


Edited by Moronium, 30 January 2019 - 05:47 AM.


#55 exchemist

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Posted 30 January 2019 - 05:49 AM

See? I told you he would hate maths.

 

They're almost always like that.   



#56 Moronium

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Posted 30 January 2019 - 05:59 AM

See? I told you he would hate maths.

 

They're almost always like that.   

 

 

In ancient times, there was a highly secretive, highly selective cult called the Pythagoreans.  They had conclusive proof that the entire universe is comprised of numbers, which they naturally worshipped, but they wouldn't share that inside information with many.

 

I said "ancient," but, truth be told, it still exists today.  They won't let me join, the bastards.

 

That's OK, though.  I'm proud to announce that I just got an invitation to a new IQ society.  Me, the moron!  Can you BELIEVE it!?

 

It's called DENSA.


Edited by Moronium, 30 January 2019 - 06:07 AM.


#57 Moronium

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Posted 30 January 2019 - 06:36 AM

The imcomprable John Lee Williamson, proving that time is relative:

 

 

My heart beat like a hammer, my eyes plumb full of tears......You've been gone about an hour, but it seems like a million years.  


Edited by Moronium, 30 January 2019 - 06:39 AM.


#58 Moronium

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Posted 30 January 2019 - 06:49 AM

The younguns might prefer Fleetwood Mac's version of the tune, eh?  They throw in some Elmore James and Buster Brown riffs on electric guitars, ya know?

 

 



#59 Moronium

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Posted 30 January 2019 - 07:21 AM

OK, I've said it elsewhere, but I'll just come out with it again here.

 

I don't believe in "spacetime."  I'll concede that it can be very useful as a strictly fictitious mathematical tool, but I can't see where it has any correspondence to physical reality.

 

True believers will rave on about how much spacetime explains, I know.

 

Their arguments bring to mind something Karl Popper once said with respect to other pseudo-scientific theoretical systems:

 

I found that those of my friends who were admirers of Marx, Freud, and Adler, were impressed by a number of points common to these theories, and especially by their apparent explanatory power. These theories appear to be able to explain practically everything that happened within the fields to which they referred.

 

The study of any of them seemed to have the effect of an intellectual conversion or revelation, open your eyes to a new truth hidden from those not yet initiated. Once your eyes were thus opened you saw confirmed instances everywhere: the world was full of verifications of the theory. Whatever happened always confirmed it. Thus its truth manifest; and unbelievers were clearly people who did not want to see the truth; who refuse to see it, either because it was against their class interest, or because of their repressions which were still "un-analyzed" and crying aloud for treatment.

 

The most characteristic element in this situation seemed to me the incessant stream of confirmations, of observations which "verified" the theories in question; and this point was constantly emphasize by their adherents. A Marxist could not open a newspaper without finding on every page confirming evidence for his interpretation of history; not only in the news, but also in its presentation — which revealed the class bias of the paper — and especially of course what the paper did not say.

 

Freudian analysts emphasized that their theories were constantly verified by their"clinical observations."  As for Adler, I was much impressed by a personal experience. Once, in 1919, I reported to him a case which to me did not seem particularly Adlerian, but which he found no difficulty in analyzing in terms of his theory of inferiority feelings, Although he had not even seen the child. Slightly shocked, I asked him how he could be so sure. "Because of my thousandfold experience," he replied; whereupon I could not help saying:  "And with this new case, I suppose, your experience has become thousand-and-one-fold."

 

 

https://staff.washin...nk/Popper-1.pdf

 

I'm not a practitioner, but I understand that professional astrologists have many elaborate mathematical and geometrical "proofs" of their tenets.  Once you accept the premises, they explain everything--with MATH, which is irrefutable.

 

As far as the laws of mathematics refer to reality, they are not certain, and as far as they are certain, they do not refer to reality.  (Albert Einstein)

 


Edited by Moronium, 30 January 2019 - 07:37 AM.


#60 OceanBreeze

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Posted 30 January 2019 - 11:02 AM

OK, I've said it elsewhere, but I'll just come out with it again here.

 

I don't believe in "spacetime."  I'll concede that it can be very useful as a strictly fictitious mathematical tool, but I can't see where it has any correspondence to physical reality.

 

True believers will rave on about how much spacetime explains, I know.

 

Their arguments bring to mind something Karl Popper once said with respect to other pseudo-scientific theoretical systems:

 

I found that those of my friends who were admirers of Marx, Freud, and Adler, were impressed by a number of points common to these theories, and especially by their apparent explanatory power. These theories appear to be able to explain practically everything that happened within the fields to which they referred.

 

 

 

 

Well, Popper, Marx, Freud, and Adler were philosophers, political theorists and psychologists, all fields where a person can be very proficient without much mathematics. A person will not get very far in engineering, physics or chemistry without a solid grasp of mathematics.

 

Einstein could not have formulated SR or GR without using some very advanced mathematics and indeed he had to rely to some extent on the previous work of Lorentz, Riemann, Gauss, Poincaré and Minkowski, just to name a few.

 

Personally, I could never understand the pursuit of mathematics for its own sake, but there are people who do think of it as an end in itself and would be very offended if someone suggested their work had some practical application!

 

I don’t think anyone is suggesting that physics is “nothing but” mathematics; there has to be a correct interpretation to go along with the equations as well.

 

A good case in point is the Lorentz transform. Lorentz was convinced that physical objects moving through the ether underwent actual physical deformation in length contraction due to an interaction of matter with the ether, while Einstein reasoned that it was space and time that changed, eliminating any need for an ether. The exact same equation was used by both men, but with entirely different interpretations.

 

Even the very basic equation, F=ma, tells us a great deal about the world that a thousand words could not. But I do admit that e=mc^2 is still very mysterious, to me at least. OK, mass and energy are the same thing, mediated by the square of the speed of light, but how should I interpret that? I still really don’t know.

 

Maybe I need to ask a philosopher?



#61 ralfcis

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Posted 30 January 2019 - 11:26 AM

 

for the explanation of e=mc2.

 

See the preceding videos for background but basically Einstein groups gamma with mass instead of velocity.

 

Also, yes the past exists but since there's no way to get to it, time is not like a space dimension. I can go back to my aunt's house but I can't go back to my aunt's house yesterday.

 

Also, you didn't get my VCR analogy about fast forward being analogous to going at twice the rate of time through time?



#62 Moronium

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Posted 30 January 2019 - 11:56 AM

Even the very basic equation, F=ma, tells us a great deal about the world that a thousand words could not. 

 

Well, I'm not sure why you say that, Popeye.  I don't think F=MA is ever presented In Newton's Principia.  He expressed his second law in basic words, i.e.:

 

A change in motion is proportional to the motive force impressed and takes place along the straight line in which that force is impressed.

 

Same with his other two laws of motion.  He first expressed them in simple words.  Putting them in mathematical form doesn't change, or add to, their meaning, it just makes them easier to "work with."

 

His first law (of inertia) basically explains what "mass" is, i.e., a resistance to acceleration. Out of this, it's easy to derive F=MA.  But that has no usefulness unless you first understand the concepts of force, mass, and acceleration.


Edited by Moronium, 30 January 2019 - 12:42 PM.


#63 Moronium

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Posted 30 January 2019 - 12:00 PM

 

I don’t think anyone is suggesting that physics is “nothing but” mathematics; there has to be a correct interpretation to go along with the equations as well.

 

 

 

I agree.  I'm not sure what anyone else is suggesting, but there has to be a correct interpretation.  And, in my view, that would necessarily entail the inclusion of a meaningful conceptual (non-mathematical) explanation which could be expressed in words.



#64 Moronium

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Posted 30 January 2019 - 12:31 PM

 

A good case in point is the Lorentz transform. Lorentz was convinced that physical objects moving through the ether underwent actual physical deformation in length contraction due to an interaction of matter with the ether, while Einstein reasoned that it was space and time that changed, eliminating any need for an ether. The exact same equation was used by both men, but with entirely different interpretations.

 

 

 

Good example.   So the question then becomes "Which is the "correct" interpretation?"  Math can't tell you that, the math is formally identical.  It has been said that the two theories are "equivalent" and that they cannot be empirically distinguished from each other. That's true, up to a point.  Most of the classical experiments would give the same results using either theory.

 

But they are not "identical" theories and they do not always predict the same results.   The advent of modern technology, such as extremely precise and accurate atomic clocks, allows for experiments that were previously impossible.

 

Basically, SR simply "imitates" LR in certain limited circumstances, and therefore derives the same answer in many cases.  But the H-K experiment, for one, illustrates where they depart from each other, and resolves the question of which one makes reliably accurate predictions.


Edited by Moronium, 30 January 2019 - 12:41 PM.


#65 OceanBreeze

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Posted 30 January 2019 - 12:48 PM

 

for the explanation of e=mc2.

 

See the preceding videos for background but basically Einstein groups gamma with mass instead of velocity.

 

 

 

 

Oh, I have seen many videos and I can derive the mathematical equivalency e=mc^2 in at least two different ways, and I have done so on this forum.

 

That still does not get at the fundamental property of mass and energy.

 

Today, we have a composed a picture that the mass of baryonic matter is contained in the binding energy of gluons and is mediated by the Higgs boson. Of course, Einstein had no clue about any of that since particle physics did not exist in his day. But there has to be a lot more to this story as baryonic matter only accounts for 5% of the mass in the universe! So, do we really know what mass is? I don’t think so. And if we don’t know what mass is, we don’t really know what energy is as they are two forms of the same thing. 

 

 

 

 

Also, yes the past exists but since there's no way to get to it, time is not like a space dimension. I can go back to my aunt's house but I can't go back to my aunt's house yesterday.

 

 

 

Yes, the time dimension is different, I didn’t say it wasn’t.

 

 

 

 

 

 

Also, you didn't get my VCR analogy about fast forward being analogous to going at twice the rate of time through time?

 

 

 

 

You still have a VCR?


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#66 OceanBreeze

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Posted 30 January 2019 - 12:50 PM

Well, I'm not sure why you say that, Popeye.  I don't think F=MA is ever presented In Newton's Principia.  He expressed his second law in basic words, i.e.:

 

 

Same with his other two laws of motion.  He first expressed them in simple words.  Putting them in mathematical form doesn't change, or add to, their meaning, it just makes them easier to "work with."

 

His first law (of inertia) basically explains what "mass" is, i.e., a resistance to acceleration. Out of this, it's easy to derive F=MA.  But that has no usefulness unless you first understand the concepts of force, mass, and acceleration.

 

 

I think those relations are made much clearer in equation form.

You are a fan of Popper so you must know he said this:

“It is impossible to speak in such a way that you cannot be misunderstood”

I find it hard to misunderstand F=ma

But, to each his own.



#67 Moronium

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Posted 30 January 2019 - 01:05 PM

I know I have made this same point many other times, but given that it came up here, I'll basically repeat it.

 

Both LR and SR hold that a clock moving at a higher speed will run slower than one moving at a lower speed. Both implement the LT to quantify this presumed difference.  But the LT don't, and can't, tell you which object is moving (faster).  Without acquiring this knowledge somehow, you can't apply the math to determine how each frame of reference "transforms" into the other, so, in itself, the formula is useless.

 

Let's say two objects agree that they are approaching each other at the rate of .6c.  Which one is moving faster?  Just knowing their relative speed can't tell you that.

 

There are an infinite number of possibilities, including that they are moving at identical speeds.  Each could, for example, be approaching the midpoint between them at the rate of .3c.  Or one could be travelling at .3001c and the other at .2999c.  Again, the possibilities are infinite.  But you must know this is in order to apply the LT.

 

How does SR determine what speed each is travelling at?


Edited by Moronium, 30 January 2019 - 01:17 PM.


#68 Moronium

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Posted 30 January 2019 - 02:18 PM

 

I find it hard to misunderstand F=ma

But, to each his own.

 

 

Well, like I said, F=MA is can't be understood unless, at a minimum, you understand the concepts of force, mass, and acceleration.

 

As demonstrated in this forum, there seems to be a fair amount of confusion and uncertainty about all of these terms.  Same with the concept of inertia (which is basically what "mass" is).  You yourself just made the point:

 

So, do we really know what mass is? I don’t think so. And if we don’t know what mass is, we don’t really know what energy is as they are two forms of the same thing.

 


Edited by Moronium, 30 January 2019 - 09:04 PM.