Merged Relativity+ / Farsight

[Farsight]

Which piece of alpha varies is a matter of convention. Constants with dimensions can vary or not - it's entirely up to you and the units you choose. It's only variation in dimensionless combinations of constants (like alpha) that means something physically. But e is the most natural choice.

Convention isn't scientific, sol. And variations in dimensionful constants mean something too.

To say that e cannot vary because of conservation of charge is completely wrong.

Oh come on sol, we're talking about e here, it's electric charge. Since when did unit charge vary? Surely even you can see an issue in saying it's a matter of convention and then dismissing conservation of charge Especially when virtual particles are virtual?

We're not talking about variations in alpha as a function of time (although even if we were, it would still be wrong).

It's indirect. Alpha varies with energy, the cosmological constant is energy density, and conservation of energy says its reducing as the universe expands.

The "running" of alpha in quantum field theory is as a function of energy scale.

No problem with that.

It occurs primarily because of virtual electron/anti-electron pairs. The vacuum is full of such pairs, and the more energy your probe has, the more of them it encounters.

No sol, the vacuum isn't. They are virtual. Space is not a seething mess of electrons and positrons popping in and out of existence. It really isn't.

Charges in a solid or a plasma get screened - they attract opposite charges and repel like charges, which means the charge inside a sphere drawn around the charge is smaller than the "bare" value of the charge. The same happens with the vacuum in QFT - that's why alpha increases at high energy.

Like I said, that's the given explanation. You can find it in the NIST fine structure constant web page. But I'm afraid that once you understand that virtual particles are virtual, you come to appreciate that it's misleading. Read that Matt Strassler article.

The idea that the type of variation of e/m coupling strength predicted by quantum field theory (the so-called running of the coupling constant alpha) is relevant to issues of fine tuning which are the theme of this thread is patently ridiculous. John Duffield has been challenged to calculate the actual variation in various scenarios, but is unable to back up his vague assertions at all with actual calculations (or is perhaps unwilling to do so, as it would immediately reveal the flaw in his argument).

No it isn't, and calculating variations is a straw man. I give you robust physics, with references. If you'd prefer to dismiss that in favour of a multiverse that's up to you, but please do not encourage others to believe in such woo. This is a skeptics forum, remember, not a forum for gullible suckers.

 

[Hellbound]

Farsight,

You have NUMEROUS threads to promote your theories.

This is not the discussion for them.

Your post(s) have been reported.

 

[Farsight]

Report away, Hellbound. I'm not promoting "my theories", I refer to Einstein and Maxwell and Matt Strassler and NIST. I'm the one giving robust physics references here to counter this multiverse woo. What are you going to do? Try and censor me because you can't bear it when some guy is skeptical about something that has no evidential support whatsoever? And which is a castle in the air sitting on "fine tuned constants" that aren't even constant?

Maybe you'd be more suited to a Roman Catholic forum, Hellbound.

 

[Perpetual Student]

The idea that the type of variation of e/m coupling strength predicted by quantum field theory (the so-called running of the coupling constant alpha) is relevant to issues of fine tuning which are the theme of this thread is patently ridiculous. John Duffield has been challenged to calculate the actual variation in various scenarios, but is unable to back up his vague assertions at all with actual calculations (or is perhaps unwilling to do so, as it would immediately reveal the flaw in his argument).

You, I and several others have asked this question many times. We can only conclude that it's merely another Duffield-make-believe physics bluff with no substance.

 

[Hellbound]

Farsight,

You have NUMEROUS threads to promote your theories.

This is not the discussion for them.

Your post(s) have been reported.

For future readers, this post (and several before and after) were moved from another thread where they were off-topic.

Farsight:

No one is even attempting to censor you. We're just asking you to quit spamming every thread with your theories.

Think of it like getting thrown out of a restaraunt because you want to stand on the table and preach. Or like getting arrested for painting your own message over every billboard you found.

No one is censoring your content. They're disallowing your method (spamming).

 

[Vorpal]

Because it is observed to be flat or very nearly flat, which means infinite or very big if you don't do something. I suppose Farsight wanted to chop it off before it grew to level 1 multiverse size.

But it doesn't mean that at all. For all we know, the universe could easily be flat and wrap around on itself on a scale not too much larger than the observable universe, which is much smaller than the the likely "level 1 multiverse size" (if that means what I think it means).

But I suppose if that was Farsight's belief, it would explain the reason why he'd want an edge. Oh well.

 

[Toontown]

But it doesn't mean that at all. For all we know, the universe could easily be flat and wrap around on itself on a scale not too much larger than the observable universe, which is much smaller than the the likely "level 1 multiverse size" (if that means what I think it means).

But I suppose if that was Farsight's belief, it would explain the reason why he'd want an edge. Oh well.

Flat and wrapped? Is that anything like a square circle?

 

[ctamblyn]

Flat and wrapped? Is that anything like a square circle?

More like a flat torus.

It's rather like PacMan world - you wander off one edge of the screen only to re-enter at the other.

 

[Toontown]

More like a flat torus.

It's rather like PacMan world - you wander off one edge of the screen only to re-enter at the other.

I'm aware of those tortured surfaces that some people try to fob off as flat space by projecting them into higher dimensions and claiming it's all good because none of the lines converge, or whatever. But it is generally agreed that "flat space" means euclidian space, which is why they call it "flat space".

Plus, a torus doesn't have an edge. So Farsight can't be talking about a torus. As I understand it, Farsight claims space is perfectly flat in the euclidian sense but can't be infinite because infinite space can't expand (I'll let Farsight explain why).

Meaning space must come to a sudden stop at an impenetrable edge. And that goes for you too if you hit the edge. And no curving back on itself, because it is perfectly flat in the euclidian sense. And yet there is nothing beyond the edge.

Apparently it's a one-sided edge. There is nothing on the other side of it, so you really can't imagine it having an 'out' side. There is no 'out' to have a side on.

It's all very strange.

 

[ctamblyn]

I'm aware of those tortured surfaces that some people try to fob off as flat space by projecting them into higher dimensions and claiming it's all good because none of the lines converge, or whatever. But it is generally agreed that "flat space" means euclidian space, which is why they call it "flat space".

It depends on the context. In some contexts "extrinsic" curvature may be particularly interesting, in which case you'd be well within your rights to call a cylinder curved. In general relativity the type of curvature of most interest is "intrinsic" curvature, as that is what corresponds to gravitation. By that measure, a cylinder or a flat torus is flat - initially parallel lines do not converge/diverge, as you mentioned, and the internal angles of a small triangle sum to 180 degrees.

Plus, a torus doesn't have an edge either. So Farsight can't be talking about a torus. As I understand it, Farsight claims space is perfectly flat in the euclidian sense but can't be infinite because infinite space can't expand (I'll let Farsight explain why).

Meaning space must come to a sudden stop at an impenetrable edge. And that goes for you too if you hit the edge. And no curving back on itself, because it is perfectly flat in the euclidian sense. And yet there is nothing beyond the edge.

Apparently it's a one-sided edge. There is nothing on the other side of it, so you really can't imagine it having an 'out' side. There is no 'out' to have a side on.

It's all very strange.

Zeus only knows what Farsight means or how it is supposed to work . I was only elaborating on Vorpal's point.

 

[Vorpal]

I'm aware of those tortured surfaces that some people try to fob off as flat space by projecting them into higher dimensions and claiming it's all good because none of the lines converge, or whatever. But it is generally agreed that "flat space" means euclidian space, which is why they call it "flat space".

"Flat space" means space that has zero curvature. It does not mean Euclidean space because Euclidean space is not the only space that has zero curvature.

Euclidean space is the only flat space that is globally isotropic, which is an assumption that the general-relativistic FLRW models make. But if one didn't grant that assumption, there's nothing particularly special about non-Euclidean flat spaces.

Plus, a torus doesn't have an edge. So Farsight can't be talking about a torus.

Yeah; I was wondering why he doesn't want a flat torus because it achieves all the stated goals so far--flatness and finitude--without really wonky edges.

 

[Toontown]

It depends on the context. In some contexts "extrinsic" curvature may be particularly interesting, in which case you'd be well within your rights to call a cylinder curved. In general relativity the type of curvature of most interest is "intrinsic" curvature, as that is what corresponds to gravitation. By that measure, a cylinder or a flat torus is flat - initially parallel lines do not converge/diverge, as you mentioned, and the internal angles of a small triangle sum to 180 degrees.

Except that the internal angles of a BIG triangle also sum to 180 in this space, so we're told, within 0.4% margin of error.

And we are also told by the people who do these measurements that a measure of the macro geometry of space really is a measure of it's magnitude. But we have to bear in mind that they only mean the 3-manifold, which may or may not contain anything except quantum stuff beyond our matter-infested region, in which case it could be quite ghostly out there, far beyond anything we'll ever be able to see.

Or not.

It's all very strange.

 

[Farsight]

For future readers, this post (and several before and after) were moved from another thread where they were off-topic.

Farsight:

No one is even attempting to censor you. We're just asking you to quit spamming every thread with your theories.

Gedoutofit. You reported my posts and JREF removed them from the megaverse thread. Because I was being skeptical about the multiverse you're peddling.

Think of it like getting thrown out of a restaraunt because you want to stand on the table and preach. Or like getting arrested for painting your own message over every billboard you found.

No, think of it as getting thrown out of a Roman Catholic church for refusing to accept something for which there is no supporting evidence, even though you give robust physics references to support your case.

No one is censoring your content. They're disallowing your method (spamming).

I'm not spamming. I'm challenging the people who are spamming the multiverse. And JREF are practicing censorship. They are siding with woo, not skepticism.

 

[Farsight]

I'm aware of those tortured surfaces that some people try to fob off as flat space by projecting them into higher dimensions and claiming it's all good because none of the lines converge, or whatever. But it is generally agreed that "flat space" means euclidian space, which is why they call it "flat space".

There's no evidence for higher dimensions. There's no evidence for a toroidal universe either. You'll recall we discussed this in the Planck thread. Like I said, there's absolutely nothing whatsoever to support the magical mysterious notion that the universe is in any way like the old Asteroids game. Or ctamblyn's Pac-Man world.

Plus, a torus doesn't have an edge. So Farsight can't be talking about a torus.

I'm not, I'm talking about a sphere. Or mathematically speaking, a ball. A ball of space, with waves running through it. This space is "flat" in that waves don't travel in some curve. They don't go thataway and end coming thisaway.

As I understand it, Farsight claims space is perfectly flat in the euclidian sense but can't be infinite because infinite space can't expand (I'll let Farsight explain why).

I've explained this many times. It's really simple. Look at the stress-energy tensor and you can see shear stress in there. That tells you immediately that Einstein thought of space being kind of "elastic". Then see the pressure diagonal, and note that Phil Plait referred to dark energy as pressure. This tells you space has an innate pressure. It's the stress-energy tensor remember, and stress is just directional pressure. In an infinite universe this pressure is counterbalanced at all locations, so it cannot drive the expansion. But as far as we can tell the universe is expanding, ergo it cannot be infinite.

Meaning space must come to a sudden stop at an impenetrable edge. And that goes for you too if you hit the edge. And no curving back on itself, because it is perfectly flat in the euclidian sense. And yet there is nothing beyond the edge.

Space comes to an end, but I can't see how light waves stop if they encounter it. I envisage they'd behave like ripples in a droplet, and would undergo total internal reflection. Since the wave nature of matter is beyond doubt, I imagine the same would apply to you. This might mean you die a terrible death, or it might mean you just find yourself travelling through familiar territory. I don't know.

Apparently it's a one-sided edge. There is nothing on the other side of it, so you really can't imagine it having an 'out' side. There is no 'out' to have a side on. It's all very strange.

But not as strange as an infinite universe that's only been around for 13.8 billion years, and started life as a point-singularity. That isn't strange, that's taking you for an idiot.

 

[Farsight]

But it doesn't mean that at all. For all we know, the universe could easily be flat and wrap around on itself on a scale not too much larger than the observable universe, which is much smaller than the the likely "level 1 multiverse size" (if that means what I think it means).

But I suppose if that was Farsight's belief, it would explain the reason why he'd want an edge. Oh well.

Oh Jeez, not the multiverse again.

Euclidean space is the only flat space that is globally isotropic, which is an assumption that the general-relativistic FLRW models make. But if one didn't grant that assumption, there's nothing particularly special about non-Euclidean flat spaces.

See the Wikipedia shape of the universe article and note that two out of three options are wrong. Something else that's wrong is the assumption that a flat universe must be infinite. There's no evidence for that whatsoever. Au contraire, the evidence supporting big-bang cosmology suggests a finite universe. And whilst I'm on a roll, there is no evidence whatsoever to support the notion that the universe is somehow curved "in a higher dimension". Zip, zero, zilch. And as for PacMan world, pah.

 

[Vorpal]

Oh Jeez, not the multiverse again.

See the Wikipedia shape of the universe article and note that two out of three options are wrong.

The wikipedia article seems incomplete, in that there are actually four distinct homogeneous and isotropic spatial geometries, rather than three. But that's neither here nor there.

Something else that's wrong is the assumption that a flat universe must be infinite.

That's not an assumption. The FLRW model assumptions are that the the universe is homogeneous and globally isotropic. If that's assumed, then the only possible flat spatial geometry is that of the (infinite) Euclidean plane.

But it's obviously not valid to say that just because the observable universe is pretty close to homogeneous and isotropic, then then whole universe must be so. Fortunately, pretty much nobody actually made such a claim--the FLRW family is an idealization to simplify things, not a literal truth. Its actual physical relevance is only that the universe around us is close to a flat FLRW model; there is no suggestion that the universe arbitrarily far away must match the same FLRW model.

Notably, inflationary models of the Big Bang tend to explicitly break the assumptions of homogeneity and isotropy rather hard anyway.

There's no evidence for that whatsoever. Au contraire, the evidence supporting big-bang cosmology suggests a finite universe.

I agree with the first statement. I don't agree with the rest--the evidence is pretty agnostic on the shape of the universe on the scale much larger than the observable universe. Because it's not observable, an claim about it is going to be based on assumptions that there is no evidence for.

And whilst I'm on a roll, there is no evidence whatsoever to support the notion that the universe is somehow curved "in a higher dimension". Zip, zero, zilch. And as for PacMan world, pah.

I don't know what you're talking about here. I don't recall this ever coming up as a claim by anyone.

 

[Reality Check]

It's woo, just like heaven and hell and unicorns and fairies.

It is a set of (speculative!) scientific theories or hypotheses, Farsight:
Multiverse

The multiverse (or meta-universe) is the hypothetical set of infinite or finite possible universes (including the historical universe we consistently experience) that together comprise everything that exists and can exist: the entirety of space, time, matter, and energy as well as the physical laws and constants that describe them.

Everybody here now knows it because I've been banging the drum about it.

Everybody here now knows it because they have bothered to go beyond your constant parroting of the assertion to the actual science: Fine-structure constant.

Conservation of energy tells you it varies over time. Unless you believe in magick. I'm telling you it varies across space too.

We are not interested in your fantasies unless you back them up with evidence, Farsight.
The cosmological constant is defined as a constant. There are theories that speculate about it varying. You have not cited any evidence that it varies.

Wikipedia is pretty good, but not always right. Spacetime is an abstract mathematical "space".

That is what the textbooks and Wikipedia say, Farsight. Of course it is idiotic to think that an abstract mathematical space is physical "space".

The cosmological constant is equivalent to an energy density in otherwise empty space, not spacetime.

That is a ignorant, Farsight.
The cosmological constant appears in GR. GR is a theory about space-time.

Then the energy density of otherwise empty space has to be reducing, doesn't it? Unless you believe in magick.

Obviously you believe in ignorance, Farsight .
It is not often made explicit but the cosmological constant leads to an energy density that remains the same throughout the history of the universe.

Try detecting space.

Try looking though a telescope or at some of the billions of astronomical images. There is lots of evidence that dark matter exists. There are plenty of candidates for what it could be. If dark matter is made of something that can be detected directly then it will be detected directly.

Bah, you know nothing.

Bah, you are still obsessed with Einstein quotes instead of learning the actual physics.
You remain unable to understand the meaning of mass–energy equivalence
Space is not a "body or system" and does not have a rest mass!

GR (and Einstein ) states that the energy of a gravitational field shall act gravitatively in the same way as any other kind of energy.

The cosmological constant is either a property of space-time (when it is on the LHS of the EFE) or a "vacuum energy" (when on the RHS). It does have does have a gravitational effect - a positive value is equivalent to a negative pressure which can be regarded as a "negative" gravity.

Disunite your silly insults ("woo", "quacks", "suckers"), the rest of the world knows that invalidating theories is a core part of the scientific process.
If there is evidence that there is no multiverse then the scientific theory of multiverse will be remembered with respect on a par with Newtonian mechanics (limited), old quantum theory (a stepping stone to modern QM) and aether theory (valid at the time but no evidence supporting it today).

 

[Reality Check]

The energy density of the cosmological constant is .. constant

duplicate

 

[Reality Check]

The energy density of the cosmological constant is constant

Farsight does not seem to know this bit of physics so Cosmological constant on ScholarPedia:

So vacuum energy and the cosmological constant have identical behaviour in general relativity, as long as the vacuum energy density is identified with,
rho^vac = Lambda\pi*G.

Thus the vacuum energy density is constant.

This is a bit strange if you only know about classical pressure in an expanding box. Obviously the energy density in this case would decrease with time there because you have the same energy in an increasing volume.

 

[Reality Check]

Like I said, that's the given explanation. You can find it in the NIST fine structure constant web page. But I'm afraid that once you understand that virtual particles are virtual, you come to appreciate that it's misleading. Read that Matt Strassler article.

Why don't you read the Matt Strassler article and try to understand it, Farsight .
He does not say that they do not exist or do not do anything. He explains what they are. The title should be a hint: Virtual Particles: What are they?

No it isn't, and calculating variations is a straw man

Actually "calculating variations " is the core of the discussion about the fine-structure constant. It is those calculations that told us that the fine-structure constant varies with energy and then that was confirmed experimentally.

It is irrelevant to this thread because that is the variation of the fine-structure constant with energy.
You are asserting that the fine-structure constant varies with time and in space. You have to provide the evidence that the fine-structure constant varies with time and in space.

The "gullible suckers" (as you put it) at least know about the real world

• There are theories about the fine-structure constant varying with time and in space.
• There are some disputed and unverified observations implying that the fine-structure constant does vary.
• This has no effect on the multiverse hypothesis. These hypothetical other universe can also have a varying fine-structure constant.

Is the fine-structure constant actually constant?

While the fine-structure constant is known to approach 1/128 at interaction energies above 80 GeV,[11] physicists have pondered for many years whether the fine-structure constant is in fact constant, i.e., whether or not its value differs by location and over time. Specifically, a varying α has been proposed as a way of solving problems in cosmology and astrophysics.[12][13][14][15] More recently, theoretical interest in varying constants (not just α) has been motivated by string theory and other such proposals for going beyond the Standard Model of particle physics. The first experimental tests of this question examined the spectral lines of distant astronomical objects, and the products of radioactive decay in the Oklo natural nuclear fission reactor. The findings were consistent with no change.[16][17][18][19][20][21]
...read further for some disputed and unverified observations...