Merged Relativity+ / Farsight

[DeiRenDopa]

Here's something mighty strange I've noticed, Farsight: as far as I can tell, these sorts of opinions are held by just one person (you). Why is that?

I'm afraid it isn't true, DeiRenDopa.

Hmm, I think I may have found at least part of the answer.

Is English not your native language, Farsight?

My statement again, with some added emphasis: Here's something mighty strange I've noticed, Farsight: as far as I can tell, these sorts of opinions are held by just one person (you).

In your reply, you stated that what I noticed (as far as I could tell), was "not true".

How can that be? Are you some kind of psychic? You have an insight into what I notice that I myself don't?

Or perhaps because, despite your millions (?) of words, in thousands of posts, over many years (and in many forums), you have failed so incredibly spectacularly, to communicate The Truth?

Nope.

I see that this is, without a doubt, your firmly expressed opinion.

It is also not backed by any evidence. Can you point to even a single post which shows that a JREF member agrees with what you posted AND disagrees with what sol and/or RC posted? I had a look back over the last dozen or so pages of this thread and could not find any such posts.

 

[Farsight]

Show that TQFT is relevant to this discussion about electric charge.

TQFT is a variant of QFT which incorporates QED which is a QM restatement of classical electromagnetism.

Show that the book you just mentioned supports your view (hint: it doesn't).

See the title. It's the Geometry of Electromagnetic Systems. Electromagnetism involves geometry.

(Regarding the context - the existence of negative curvature in spatial slices through spacetime...)

"Then you're talking about electromagnetism."

Nope, gravitation.

Yes, electromagnetism. How many times do I have to draw your attention to The role of the potentials in electromagnetism where you can read "We conclude that the field describes the curvature that characterizes the electromagnetic interaction." There's a curvature associated with gravitomagnetism which is different to the spacetime curvature associated with gravity. Gravitomagnetism is related to electromagnetism. There's a curvature associated with that too.

(Regarding the large-scale curvature of the observable universe...)

"I say it's zero"

Possibly, but it would be very remarkable if it were exactly zero. It isn't relevant to my next point, so I'll put that aside for now.

It's exactly zero, and it isn't remarkable at all. Because on the large scale, space is homogeneous, so there no gravitational field, and expansion apart, spacetime is therefore flat.

(Regarding my pointing out that spatial slices through the Schwarzschild solution have negative curvature...)

"You can plot the Flamm paraboloid using light clocks in an equatorial plane. The curvature isn't actually curved space, it's a curvature in your measurements. Your metric."

No, it's genuine honest-to-goodness spatial curvature.

No, it isn't. GR refers to the geometry of spacetime. The space around the Earth isn't curved, it's inhomogeneous, and therefore motion through it over time is curved. Again see this article on John Baez's website, where you can read this: "Similarly, in general relativity gravity is not really a 'force', but just a manifestation of the curvature of spacetime. Note: not the curvature of space, but of spacetime. The distinction is crucial." You know that it isn't curved space, because if it was, a ball would travel the same arc regardless of how fast you threw it.

You can measure it without any clocks at all like so:

Create a very large circle out of string (or dental floss or whatever) centred around a star, being careful to ensure that it is stationary with respect to the star, and measure the circumference C_inner of the circle. Now, create a second circle by moving each point of the first circle radially outwards by a short distance a (small in comparison with C_inner), measured locally using standard metre sticks. This will require you to either stretch the string, if it allows, or splice in some extra. Now measure the circumference C_outer of the new circle.

If there were no spatial curvature, the circumference of the second circle could only be

C_outer = C_inner + 2πa .
​

This formula must hold if the spatial geometry is Euclidean - most teenagers could provide the proof. However, according to GR if you perform this experiment you will find that

C_outer = C_inner + 2πa√(1 - 4πM/C_inner)
​

where M is the mass of the gravitating body in units where G = c = 1. Thus, the space is not Euclidean.

Wrong. See above. You defined your metre using the motion of light through space. That's the most fundamental way to do it, and it takes you right back to those the light clocks on the equatorial plane. The motion of light through space is not constant, so your metric is not Euclidean. Because space is inhomogeneous. And as a result the motion of light through space over time is curved. It's what Einstein said, ctamblyn. He said light curves because the speed of light varies with position, not because space is curved, and not because spacetime is curved either. Learn to distinguish cause and effect.

 

[ctamblyn]

TQFT is a variant of QFT which incorporates QED which is a QM restatement of classical electromagnetism.

No, don't hand-wave. Show that TQFT incorporates QED.

See the title. It's the Geometry of Electromagnetic Systems. Electromagnetism involves geometry.

No, don't hand-wave. Show that the book itself supports you, not that you can pick words out of a title.

Yes, electromagnetism.

Nope, it's still gravitation. This started when W.D.Clinger pointed out that negative curvature exists in GR (ETA: here), not e/m, and you objected. I then pointed out that negative curvature exists all over the place in GR.

It's exactly zero,

Evidence?

...and it isn't remarkable at all. Because on the large scale, space is homogeneous, so there no gravitational field,

Non sequitur.

and expansion apart, spacetime is therefore flat.

Non-sequitur.

(Regarding me showing that the spatial sections throught the Schwarzschild solution exhibit negative curvature.)

No, it isn't.

Then you are using (useless) private definitions of curvature which no-one else in the field uses. According to the standard definitions as understood by every mathematician since Gauss and every physicist since Einstein the spatial sections through the Schwarzschild geometry have negative curvature.

(Regarding an explicit calculation done within the framework of GR, showing the existence of curvature in the spatial slices through the Schwarzschild solution.)

Wrong. See above. You defined your metre using the motion of light through space.
...

I'm sorry, but you simply don't know what you're talking about here. Whatever length standard you use will show the discrepancy in the circumference measurements I calculated. You can use the wavelength of light emitted in a particular atomic transition if you want, but you can also use mean travel distance of beta-decaying particles (with no e/m involved). It doesn't matter. The same formulae apply, because the curvature is actually there.

 

[Farsight]

You do actively promote it, in the sense that you are more then merely mentioning as a possibility, you are claiming that it is the The Truth

Stop banging on about it. I give the explanation and the logic, and you can't offer anything to counter it apart from vague toroidal abstraction that fails to satisfy Toontown along with everybody else including yourself.

No, yet again, because expansion occurs in the infinite FLRW models too, and those have the great benefit of actually being solutions of the GR field equations, unlike your fantastical finite flat universe.

It isn't fantastical. WMAP etc evidence indicates that the universe is flat, and the standard model of cosmology does not say the early universe was infinite. And as I said, two out of three of those FLRW "solutions" are definitely wrong. They can't all be right. And it is a non-sequitur for you to insist that the flat solution demands an infinite universe that was even infinite when the big bang occurred.

The evidence is currently inadequate to answer that question definitively. However, you are attempting to shift the burden of proof. You claim the universe must be finite because (a) GR and (b) it is expanding, and you cannot support that claim (because it is utterly wrong).

I've explained it in simple terms that everybody can understand: GR features the stress-energy-momentum tensor. It has a pressure diagonal. Phil Plait likened dark energy to pressure. If the pressure is counterbalanced at all locations, expansion cannot occur. You have no counter to this. You are reduced to saying "utterly wrong". It cuts no ice.

Yep.

No, the infinite universe isn't consistent with the standard model of cosmology. If you think it is, please refer to a description of the such which features a universe that was already infinite when the big bang occurred, and then give your evidential or logical support for any such assertion. There isn't any, and you know it. Which is why I smell another "utterly wrong" coming on.

 

[ctamblyn]

Stop banging on about it. I give the explanation...

You posted a lot of stuff, repeatedly. However, Friedmann, Lemaître, Robertson and Walker demolished your "explanation" with their explicit solutions to the GR field equations, long before the internet existed.

(As for the toroidal thing, I'm not sure why you keep bringing it up. That was a conversation between Toontown and I, which has already finished.)

It isn't fantastical.

It is fantastical to claim that expansion proves the universe is finite within the framework of GR. Again, see: FLRW solutions.

 

[Farsight]

Hmm, I think I may have found at least part of the answer.

Is English not your native language, Farsight?

English is my first language. I'm John Duffield, I live in Poole. That's in England. I was born in Manchester. That's in England too.

My statement again, with some added emphasis: Here's something mighty strange I've noticed, Farsight: as far as I can tell, these sorts of opinions are held by just one person (you).

In your reply, you stated that what I noticed (as far as I could tell), was "not true".

How can that be? Are you some kind of psychic? You have an insight into what I notice that I myself don't?

I see that this is, without a doubt, your firmly expressed opinion.

It is also not backed by any evidence. Can you point to even a single post which shows that a JREF member agrees with what you posted AND disagrees with what sol and/or RC posted? I had a look back over the last dozen or so pages of this thread and could not find any such posts.

You didn't do any such thing. If you did you would have seen edd's post on page 27, only three pages back. So your dishonesty is exposed. People do agree with me. Here, feast your eyes on this:

"this wouldn't be the first time I've expressed a small very carefully worded element of agreement with you".

When people agree with me, some have been forced to concede, whereupon they go quiet on us, Dopa. As ctamblyn will do shortly, when I force his confusion between curved space and curved spacetime down his throat. I can see from his latest post that he's getting desperate, bleating about "hand waving" and the like. So utterly unconvincing. You best not look Dopa, it isn't going to be pretty.

But ah, look at the time. Time for bed.

 

[ctamblyn]

I can see from his latest post that he's getting desperate, bleating about "hand waving" and the like.

Well, how unfair of me to expect someone to actually support their questionable assertions with something more than cherry picking words out of a book title!

See the title. It's the Geometry of Electromagnetic Systems. Electromagnetism involves geometry.

 

[Farsight]

Ah, now it's "cherry picking". Now that's a convincing counterargument.

I will nail you on your curved space error, ctamblyn. You would be best to concede now. People think more highly of people who say Sorry, my mistake. They don't think highly of people who demonstrate insincerity and keep digging themselves into a hole.

Anyway, like I said, time for bed, so mañana.

 

[ctamblyn]

Ah, now it's "cherry picking". Now that's a convincing counterargument.

"Counterargument" would imply that I was responding to an actual argument. In fact, when asked to show that a book supported your position about the nature of electromagnetism, all you did was say "see the title!"

I suggest that is because you unable to show that the actual contents support you.

 

[DeiRenDopa]

English is my first language.

OK, so I guess the next best hypothesis for your - screamingly obvious - inability to understand simple English is that your reading comprehension is about the same as no better than that of a Grade 8 (?) student.

I'm John Duffield, I live in Poole. That's in England. I was born in Manchester. That's in England too.

Yes, I see that you've said this.

Many times.

It is also not backed by any evidence. Can you point to even a single post which shows that a JREF member agrees with what you posted AND disagrees with what sol and/or RC posted? I had a look back over the last dozen or so pages of this thread and could not find any such posts.

You didn't do any such thing. If you did you would have seen edd's post on page 27, only three pages back. So your dishonesty is exposed.

Hmm, so that - I think - constitutes pretty darn good evidence for what I wrote.

Yes, edd did write that (and yes, I did see it).

However, it does not seem to be relevant.

Why?

Because of this: "AND disagrees with what sol and/or RC posted".

Farsight's reading comprehension 0, DeiRenDopa's statement 1.

People do agree with me. Here, feast your eyes on this:

"this wouldn't be the first time I've expressed a small very carefully worded element of agreement with you".

Yeah, there's that reading comprehension thing again. Pesky, it is.

Of course, I could be quite wrong (I often am); it may well be that you engage in these sorts of 'quote out of context' games often, and coldly deliberately. It may well be that this is your MO, one that you've refined over many years.

When people agree with me, some have been forced to concede,
[irrelevant text snipped]

I do not doubt that, not for one second.

However, it's completely unrelated, and irrelevant, to what I wrote. Honestly, what would you rate your own reading comprehension level to be? Grade 6?

 

[ctamblyn]

I will nail you on your curved space error, ctamblyn.

Sure. Let's make sure we remember where we are in the morning.

1. I claimed that spatial sections through the Schwarzschild geometry have negative curvature.

2. You claimed that it wasn't actually spatial curvature.

3. I showed how GR predicts a departure from Euclidean-ness in the spatial part of metric, using a measurement which doesn't depend on clocks.

4. You tried to claim that my rods were dependent on the motion of light through space.

5. I pointed out that many choices of rod are possible, not just light-based ones, and all will agree because they are all responding to the same curvature of the same space.

For a ruler, just to avoid confusion, I will use a near-monochromatic source of neutral delta baryons, and measure the distance they need to travel before half the the particles have decayed via the strong force. That way we get a perfectly good ruler without needing to appeal to electromagnetic interactions.

 

[Reality Check]

Yes. Of course I do. I've understood it for decades.

That is strange because you seem ignorant about this "kid's stuff" having of space-time intervalsbeing positive, zero or negative.
You need to read the question again:
Do you now understand the meaning of Space-time interval and its values (positive, zero and negative)?
First asked 26 July 2013 - 4 days and counting.

Wow, Farsight. Your answer to
Farsight: Do you now understand the meaning of infinity?
is to cite the Wikipedia article I cite to you !
At last we will not longer see the mistake of treating infinity as a number from you.

I've told you already. It's Einstein's Leyden Address where he referred to a gravitational field as inhomogeneous space.

That is wrong in so many ways, Farsight:

• A speech is not a good source. A paper or text book is a good source.
• That speech never mentions your claim that "a homogeneous universe is a flat universe"

Farsight: Source for "a homogeneous universe is a flat universe"
First asked 26 July 2013 - 4 days and counting.
Remember - "The statements are wrong" is an answer!

1. Expansion

The inanity of a one word unsupported assertion should be obvious even to you, Farsight !
This is especially true when the standard cosmological models are of an infinite expanding universe so expansion is not evidence for finiteness.

Farsight: Can you list the evidence for a finite universe?
First asked 26 July 2013 - 4 days and counting.

But I can say it can't be infinite, because if it was it couldn't expand.
...snipped irrelevant gibberish....
...snipped irrelevant stuff about black holes ....

Farsight Show mathematically that an infinite universe in GR cannot expand.
First asked 26 July 2013 - 4 days and counting.

Farsight: Support your assertion that GR conserves energy
First asked 26 July 2013 - 4 days and counting.
This is GR in general not the case of black holes.

All: Reality Check will now say I haven't answered his questions at all, and will keep on repeating them.

All:
Reality Check actually says that Farsight wrote replies to all of the questions.
Reality Check actually says that Farsight answered a trivial part of 1 question (he knows the space-time intervals exist) and parroted a citation that I gave him. The rest of the replies are either wrong or irrelevant.

 

[Reality Check]

And like I said, the volume of the ball isn't negative.

Farsight, everyone knows that that volume of the ball is not negative - really needs a duh!

What everyone (except you evidently) knows is that Ricci curvature is not the volume of a ball . Read what you quote:"represents the amount by which the volume of a geodesic ball in a curved Riemannian manifold deviates from that of the standard ball in Euclidean space".
Which reminds me:
Farsight: Do you now understand the meaning of Ricci curvature? 26th July 2013 - 4 days and counting.
That is Ricci curvature represents a difference between volumes of 2 balls, not the volume of one of the 2 balls mentioned.

 

[Reality Check]

Wrong. If the energy-density is uniform, there is no gravity.

Wrong, Farsight.
A non zero "energy-density" always produces curvature of space-time. According to GR (and you!) curvature of space-time is gravity.
See this article on John Baez's website, where you can read this: "Similarly, in general relativity gravity is not really a 'force', but just a manifestation of the curvature of spacetime. Note: not the curvature of space, but of spacetime. The distinction is crucial."

Light always goes "straight", i.e. follows a geodesic.

Curvature of space-time is never caused by "delta" energy density - see the Einstein field equations where there is only the stress-energy tensor, not any difference between any energy densities.

ETA:

How an infinite universe can possible square with the standard model of cosmology absolutely beats me.

Luckily it does not beat cosmologists or people who actually learn about the standard model of cosmology.
The basic concept is quite simple. You first ask how can you define the size of a universe. The answer is that you cannot if the universe is infinite. So instead you basically look at distances between points which is good because

• that is how the geometry of space-time is defined in GR (via metrics).
• this includes finite universes.

Add in the assumptions that this infinite or finite universe is isotropic and homogeneous and there is an exact GR solution: Friedmann–Lemaître–Robertson–Walker metric.

 

[Perpetual Student]

(Regarding Mr. Duffield)

Of course, I could be quite wrong (I often am); it may well be that you engage in these sorts of 'quote out of context' games often, and coldly deliberately. It may well be that this is your MO, one that you've refined over many years.

You are not wrong. But no one here has been fooled; it's a tired debating tactic that has become quite transparent to all.

 

[lpetrich]

About GR, Farsight thumps Einstein's Leyden Address as if it was some inspired book, inspired in the theological sense of the word. I think that Einstein was being less-than-precise in a nontechnical sort of lecture. Nontechnical expositions are *not* the primary statements of physical theories, and one will get into a *lot* of trouble by supposing that they are.

Even worse, rejecting Farsight's interpretations of Einstein's works he interprets as rejecting Einstein.

Farsight also notes the NIST page Current advances: The fine-structure constant and how it states that the FSC is a "running" constant. He ignores the details of its running, details that some of us have tried to explain to him, details mentioned in that page itself. He even waves away calculation of this running as somehow a distraction from the fact of the running itself.

That's the sort of arguments that I call arguing like a theologian.

 

[Farsight]

I'm no theologian, lpetrich. Au contraire, it was you who referred to intelligent design on the multiverse thread. There's just as much evidence for the multiverse as there is for intelligent design. And puhlease, I don't ignore details of running constants. I'm the one who is forever pointing them out. As for interpretations of Einstein, see arXiv. I'm no book thumper. You're the book thumper round here, I'm the skeptic.

 

[Reality Check]

I'm no theologian, lpetrich. Au contraire, it was you who referred to intelligent design on the multiverse thread.

Not quite right, Farsight.
lpetrich's reference was to intelligently designed universes not the creationist intelligent design:

As to our Universe being intelligently designed, for all we know, our Universe could be part of a lab experiment in making universes. That is also consistent with the Universe being borderline habitable -- the experimenters haven't figured out a simple way to make a super habitable Universe.

This is a common speculation about the nature of the universe, i.e. the universe as a computer simulation. The nature of computer simulations is that they are usually run multiple times with different parameters and often in parallel. Thus "universe as a computer simulation" means many universes being simulated, i.e. a multiverse.

What you ignore about the details of running constants is a couple of basic facts.

• Change the value of the running constants at zero energy and you change them for all energy.
• We can think about universes with different running constants. This is usually expressed in terns such as "let us look at what happens in a universe where the fine-structure constant is different from our universe".

 

[Perpetual Student]

Mr. Duffield is a man of dogma. There is no place for speculation in his universe of physics based on book titles, descriptive notes, speeches and pretty pictures.

 

[Farsight]

So says the guy who started the multiverse thread.

RC: the universe is not some computer simulation!

Why is it that JREF is infested by cuckoo-in-the-nest suckers who believe in woo with such utter conviction that they reject simple straightforward relativity backed by Einstein references and hard scientific evidence? Answers on a postcard please.