Universe's expansion may be understood without dark energy

[Cheetah]

Have a look at http://physics.nist.gov/cuu/Constants/alpha.html

Thanks for the link!




That next paper really needs its own thread thread, I'll do so, please carry on there. I really enjoying your discussions.

 

[sol invictus]

He was simply talking about the speed of light.

"Speed" is distance over time. To measure speed you therefore must choose coordinates.

No it doesn't, you do. And the evidence proves it. The Shapiro delay is a delay.

Farsight, Shapiro time delay is a prediction of GR. It's trivial to derive from GR. So how can it possibly be evidence against GR?

When people say "the speed of light is constant", they mean something specific, something which was quite well explained in that Baez link you posted earlier. And what they mean by that is perfectly consistent with Shapiro time delay.

My general position is that expert skeptics can behave like creationists at times, abusing their authority to discredit scientific evidence that challenges their position.

Your position has been undermined at every turn by the fact that you don't understand what you're talking about. Not to mention that no one participating in these threads can possibly "abuse their authority", since we are all anonymous posters on someone else's forum.

 

[Dancing David]

Dancing David: Let's talk about that paper on another thread. But meanwhile look at the title again. It starts with the word evidence. Please don't try to dismiss it, or the fact that the fine-structure constant isn't constant, by throwing ad-hominem abuse at me.

I think you must be very sensitive to think that was an ad hom, the error bars and the graph look really funny, did you notice that?

Did you look at the error bars or not?

 

[ben m]

If we were sitting here in 1923 talking about some guy called Einstein, I suspect there would be people saying he made a mistake once and telling people to ignore everything he says.

There sure were---especially (pace Godwin) the Nazis, who didn't like it because it was discovered by a Jew, and attempted to set up a whole school of "German Physics" in explicit opposition to "Jewish Physics".

And there are people saying that *today*---about Einstein, Schrodinger, Hubble, Bardeen, Darwin, Bohr, Maxwell, Koshiba, and probably Isaac Newton for all I know. "Ignore Maxwell, he made a mistake, which I have corrected, and I have used the corrected laws to build a free-energy machine."

What's your point? Oh, right, a general argument that "new ideas" are automatically rejected. They're not. New ideas are tested carefully, with very high standards of proof (to overcome the "trials penalty", since the number of theories far exceeds the number of true theories), which is basically the right thing to do.

 

[W.D.Clinger]

See above. It's the other way round - there's an issue with the "locally-STR nature of spacetime" in that it's of infinitesimal extent. I'm not happy with Einstein's usage of this, but nobody's perfect. It means it's actually of zero extent. So it isn't actually there at all.

Farsight, let me introduce you to the subject of calculus:

Calculus, this is Farsight. He may never have heard of you, but you have much to teach him about limits and infinitesimals.​

 

[Vorpal]

He was simply talking about the speed of light. Here's the quotes again:

1911: If we call the velocity of light at the origin of co-ordinates co, then the velocity of light c at a place with the gravitation potential Φ will be given by the relation c = co(1 + Φ/c²).

Here is some context (hi-lite mine):

For measuring time at a place which, relatively to the origin of the co-ordinates, has the gravitation potential Φ, we must employ a clock which--whenremoved to the origin of the co-ordinates--goes (1+Φ/c²) times more slowly than the clock used for measuring time at the origin of the co-ordinates. If we call the velocity of light at the origin of co-ordinates c₀, then the velocity of light c at a place with the gravitation potential Φ will be given by the relation
[latex]$c = c_0\left(1+\frac{\Phi}{c^2}\right)$[/latex]
The principle of the constancy of the velocity of light holds good acoording to this theory in a different form from that which usually underlies the ordinary [special] theory of relativity.​

That's precisely what people have been telling you across different threads. By the way, that relationship is actually a bit off, but that's because that's Einstein in 1911, a half-decade before general relativity.

What he actually said in 1916 was die Ausbreitungs-geschwindigkeit des Lichtes mit dem Orte variiert which translates to the speed of light varies with the locality. The word velocity appears in the translation, but this is the common usage rather than the vector quantity.

Of course it does. That's because he's talking about the coordinate speed.
In the passage you've for some reason cut out, he says "the principle of the constancy of the velocity of light holds good ... in a different form," which again, is what people have been telling you.

No it doesn't, you do. And the evidence proves it. The Shapiro delay is a delay.

Of course it is. As Sol says, you can calculate pretty easily... but you don't even have to do that exactly. Already from the PPN calculation (post #40) it's obvious that it's going to be proportional to (γ+1) in the weak-field limit. That's why I brought it up way back in post #34: GTR predicts γ = 1, Annila, as far as the prediction makes any sense, has γ = -1/2, so Shapiro delay will be off by a factor of four.

That was the point: even if Annila fixes deflection of starlight by the Sun (and I don't understand his reasons), a lot more things are broken by messing about with light propagation in this way. They will all need to be fixed, which also would be an impressive trick for experiments like GPB's in particular because they aren't even directly connected to light propagation.

Now think about what Einstein said, and think of the two light beams like they're racehorses. Are they really going at the same speed?

Which speed? Do the calculation yourself in any configuration of any non-flat spacetime of your choosing. You will see what's varying is the coordinate speed plain as day.

My general position is that expert skeptics can behave like creationists at times, abusing their authority to discredit scientific evidence that challenges their position. My particular position with GR is Einstein's position: that the speed of light varies and space is inhomogeneous. The "modern interpretation" of GR takes a different position.

All that's different in the "modern interpretation" is purely a value judgement: this "different form" in the Einstein quote is considered more fundamental. But there is zero physical difference, and both of Einstein's statements are completely accomodated. I don't know why you're making it out to be such a big deal.

There is no calculating it. We use the motion of light to define the second and the metre.

If you think NIST retroactively broke GTR somehow, do the calculation a physicist should be doing in a hypothetical world where the meter is still defined using a platinum-iridium bar. Or any physicist ca. 1930-1960.

See above. It's the other way round - there's an issue with the "locally-STR nature of spacetime" in that it's of infinitesimal extent. I'm not happy with Einstein's usage of this, but nobody's perfect. It means it's actually of zero extent. So it isn't actually there at all. If it was, it would mean that according to Einstein space was locally homogeneous, so things wouldn't fall down.

Einstein may not have been perfect, but on this matter he was right on target.

Say you live in a Newtonian universe. There's a gravitational potential Φ. You're in freefall, say in orbit on the ISS around the Earth. Everything around you in freefall, so you don't detect any gravity and things look just like an inertial frame.
... but what happens over finitely extended intervals?
You and an object that is at a slightly different elevation have different orbits, so if you watch it very carefully, you can detect the fact you're in a gravitational field. That's where the 'infinitesimal' bit comes in, but the reason why you have to watch it very closely in the first place is that what you're observing are the gravitational tidal forces, and they're given by the second derivatives of the potential.

Far from being a defect in Einstein's thinking, the way in which the local intertial frames deviate corresponds to something essential to the interpretation of spacetime as a curved manifold. Instead of Newtonian local inertial frames, you have STR local inertial frames, the gravitational potential is the spacetime metric, and the tidal forces are determined by, surprise, its second derivatives... and they are exactly the Riemann curvature.