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Comment author: DanielLC 20 September 2014 09:18:13PM 1 point [-]

4: the infinity is not even a coherent concept

What do you mean by this? Do you just mean that it doesn't make any sense for something infinite to actually exist, or do you mean that set theory, which claims the existence of an infinite set as an axiom, is inconsistent?

6: Venus is hot due to volcanoes

Why? It seems to me that it would be obvious if the standard theory that Venus gets most of its heat from the sun was wrong, since we can easily see how much it absorbs and emits and look at the difference. Besides which, you'd need expertise to have a reasonable chance of coming up with the correct explanation on your own. Do you have relevant expertise?

Comment author: Thomas 21 September 2014 09:12:51AM 0 points [-]

Well, I have learned that explaining one of my views from this thread just costed me karma points.

I'll pass those two.

Comment author: Mark_Friedenbach 20 September 2014 04:27:26PM 2 points [-]

Is that healthy or realistic?

Comment author: Thomas 20 September 2014 05:44:06PM 6 points [-]

It's not realistic. MIRI has nothing to show in the field of AI.

Comment author: Thomas 20 September 2014 04:10:13PM 1 point [-]

The official LW attitude as I understand is: Don't do it at home, might be incredibly dangerous - MIRI will do it for you!

Comment author: army1987 20 September 2014 11:03:14AM 1 point [-]

(Why are you expecting apparent sizes to match real sizes in the first place? The Sun looks as small as the Moon as seen from Earth, do you think it actually is?)

Of all light rays entering your eye right now, the ones coming from parts of the object farther away from you departed earlier than the ones coming from parts closer to you. If the object moved between those two times, its image will be deformed in a way that, when combined with Lorentz contraction, foreshortening, etc., will make the object look the same size as if it was stationary but rotated. This is known as Terrell rotation and there are animated illustrations of it on the Web.

(BTW, galaxies are moving along the line of sight, so their Lorentz contraction would be along the line of sight too, and how would you expect to tell (say) a sphere from an oblate spheroid seen flat face-first?)

I agree that “Lorentz contraction” is a misleading name; it's just a geometrical effect akin to the fact that a slab is thicker if you transverse it at an angle than if you transverse it perpendicularly.

Comment author: Thomas 20 September 2014 04:07:44PM 0 points [-]

will make the object look the same size as if it was stationary but rotated

Yes. Rotated rope looks shorter. Problem remains.

galaxies are moving along the line of sight

We see the close and the far edge of many of them. Still, the pancake apparently isn't neither squeezed neither rotated.

Comment author: army1987 19 September 2014 12:47:33PM 1 point [-]

Hubble flow is at best a very noncentral example of travelling. Also, images aren't supposed to show any contraction (see Terrell rotation), only the objects themselves.

Comment author: Thomas 19 September 2014 01:44:34PM -1 points [-]

If images aren't supposed to show any contraction, then measurements aren't supposed to detect any contraction.

My point exactly.

Are you saying, that there in an invisible contraction?

Comment author: army1987 19 September 2014 12:21:44PM 0 points [-]
Comment author: Thomas 19 September 2014 12:35:54PM -1 points [-]

The link you gave does not talk about the direct observation of the Lorentz contraction. Rather of "explanations".

Fast traveling galaxies, of which all the sky is full, DO NOT show any contraction. That would qualify as a direct observation.

Comment author: army1987 19 September 2014 08:39:18AM 0 points [-]

They say those packets don't qualify for the contraction as they are "not rigid in Born's sens" and therefore not shrinking.

A bunch of particles not bound to each other by anything is not rigid in any reasonable sense I can think of, so what's your point?

Comment author: Thomas 19 September 2014 09:06:19AM *  0 points [-]

Every rigid body is just a cloud of particles. If they are bonded together, they are bonded together with other particles like photons. Or gravity. Or strong nuclear force, as quarks in protons and neutrons.

Also the strong nuclear force is responsible for bounding atomic nucleus together. The force just doesn't stop at the "edge of a proton".

But why do you think they "must be bonded together" in the first place?

Comment author: gjm 18 September 2014 10:45:21PM 0 points [-]
Comment author: Thomas 19 September 2014 07:37:31AM -1 points [-]

This description fits only for protons at such ultrahigh energies that even the most advanced experiments will probably never be able to detect them.

See? It's only calculation based on Relativity, not actual experimental data.

Comment author: gjm 18 September 2014 09:17:17PM 1 point [-]

To get direct verification of length contraction we'd need to take something big enough to measure and accelerate it to a substantial fraction of the speed of light. Taking the fact that we don't have such direct verification as a problem with relativity is exactly like the creationist ploy of claiming that failure to (say) repeat the transition from water-dwelling to land-dwelling life in a lab is a problem with evolutionary biology.

Comment author: Thomas 18 September 2014 10:00:55PM -2 points [-]

We have. The packet of protons inside LHC, Geneva.

Packets all around the circular tube. Nobody says, they shrink. They say those packets don't qualify for the contraction as they are "not rigid in Born's sens" and therefore not shrinking.

If we can measure even a tinny mass gain, we could measure a tinny contraction.

Had there been any.

Comment author: gjm 18 September 2014 07:42:39PM 0 points [-]

Yeah, but it's a "paradox" only in the sense of being confusing and counterintuitive, not in the sense of having any actual inconsistency in it. The point is that this is a situation that's already been analysed, and your analysis of it is wrong.

Comment author: Thomas 18 September 2014 08:34:10PM -1 points [-]

It wouldn't be a problem, if it was just "paradox", but unfortunately it's real.

We can't and therefore don't measure the postulated Lorentz contraction. We have measured the relativistic time and mass dilatation or increase, we did. But there is NO experiment confirming the contraction of length.

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