# Thread: Length Contraction in the Muon Experiment

1. Originally Posted by Aer

This seems like an ex post facto argument. How might you reach this conclusion using Special Relativity laws only a prior?
It is not a conclusion, it is a intial condition of the test. The muon crosses the depth of the Earth's atmosphere as measured in both frames.

Are you sure this predicts what you say it will predict?

2. Originally Posted by Janus58
It is not a conclusion, it is a intial condition of the test. The muon crosses the depth of the Earth's atmosphere as measured in both frames.

It appears we are approaching the problem from different perspectives. The only condition related to special relativity in the experiment is the fact that the muon is created and decays and at all points in time (from the muon's perspective or the Earth's perspective) the muon is travelling at .998c. Is this correct? the fact that the muon reaches the Earth's surface is not a condition of the experiment or special relativity, it is a result.

3. Concerning the Muon Experiment:

The muon doesn't see time dilation in it's own frame nor does the Earth. So both their clocks are ticking along at the same rate in their respective frames but they see the other's clock tick slower.
Yes.

The muon is explained by saying the Earth sees the muon's clock slower
Yes.

and the muon, with a normal tick rate in it's own frame, sees the Earth move over a smaller distance.
Yes.

This argument seems inadequate to me because isn't the reverse true if neither frame is preffered. That is, the muon sees the Earth's clock slower while the Earth sees the muon move a smaller distance.

Can anyone point out where this thinking is flawed? I have not been able to resolve this issue and would like to!
No.

The muon sees all distances and lengths that have relative velocity to it as contracted.

The earth sees all distances and lengths that have relative velocity to it as contracted.

In our rest frame, the muon is created 10000m up and must traverse that distance. In the muon's rest frame it is created 600m up and need only traverse that distance.

Consider time for the muon, in order for no light to reach it beyond the edge of the known universe as defined in the earth frame (156b ly) and the muon frame (9.6b ly), then the time accumulated on the muons clock
...
would have to be less than that accumulated on the Earth clock.
Assume muon v = 0.79c Distance to traverse in earth frame = 15.6b ly. When we meet:

On the earth, we would see the muon clock at 12.0by with our clock at 19.7by.

Now, when the muon is created the distance it must travel in its frame is only 9.6bly and will take it 12by on it's own clock.

So, the muon would read our clock at 7.3by with its clock at 12by

That statement does not agree with the statement that each clock ticks normally in their own frame and each sees the other clock as running slower.
Yes, it does.

Hopefully this helps?

4. Originally Posted by Aer
That is, the muon sees the Earth's clock slower while the Earth sees the muon move a smaller distance.
Originally Posted by superluminal

No.

The muon sees all distances and lengths that have relative velocity to it as contracted.

The earth sees all distances and lengths that have relative velocity to it as contracted.

In our rest frame, the muon is created 10000m up and must traverse that distance. In the muon's rest frame it is created 600m up and need only traverse that distance.
Ah ha! This is more of the answer I was looking for. However, from the muon's perspective, the Earth travels 600m, as the muon doesn't consider itself "traversing". Anyway, thank you superluminal. I'm still not sure that the other issue has been resolved.

5. Anytime. And of course you are right, the muon is happy in its rest frame and all else moves about it.

Which was the other issue? The accumulated time thing?

6. Originally Posted by superluminal

Assume muon v = 0.79c Distance to traverse in earth frame = 15.6b ly. When we meet:

On the earth, we would see the muon clock at 12.0by with our clock at 19.7by.
That is all well and good, but what would the muon see when we meet?

Originally Posted by superluminal
Now, when the muon is created the distance it must travel in its frame is only 9.6bly and will take it 12by on it's own clock.
I think the issue of who is considered travelling is confused here.

Originally Posted by superluminal
So, the muon would read our clock at 7.3by with its clock at 12by
This is of course assuming the muon's frame is length contracted and on second thought, I am not sure about my agreement with you on the post above.

Originally Posted by superluminal
Hopefully this helps?
Hopefully I'll be able to reconsider the issue from what you have said and express my thoughts in a more clear manner.

7. Hmmm... Ok

8. Sorry about the "who is travelling" confusion. I have trouble sometimes yanking myself out of my own rest frame and into another.

9. Aer:

This is of course assuming the muon's frame is length contracted and on second thought...
From the muons POV (travelling at .79c or whatever) the universe exists in a contracted state. What appears to us to be 15.6bly is, to the muon, only 9.6bly. The earth only travels () that distance to the muon.

10. Originally Posted by superluminal
Geist you fucking asshole. Back to the pseudoscience forum and let people discuss actual science.

If you don't want to read all this, they use balloon lofted instruments and know very well the muon fluxes in the upper atmosphere.

http://hyperphysics.phy-astr.gsu.edu...ativ/muon.html

http://www.cosmicrays.org/

http://www.lbl.gov/abc/cosmic/SKliew...Rays/Muons.htm

http://pandora.physics.lsa.umich.edu..._70_092005.pdf

http://people.roma2.infn.it/~aldo/A51prl_cap94_mu.pdf

And the explanation for why muons with a HALF-LIFE of 2.2us reach the ground, is that from our frame, the muon lasts much longer. From the muon's frame an earth clock would also appear to run slower.
Sl, One paper you provided (see link below) show muon creation over three orders of altitude magnitude.

While I am in the process of matching the use of d/m<sup>2</sup> terms to determine altitude
this paper indicates variation (experimental data) of muon fluxes with altitude.

Notice that these data indicate muons created at altitudes nearing the planet surface. I have seen no information in this forum other than SRT claims that time dilation accounts for the muons reaching the planet surface. Obviously these data in the paper cited above show experimental contradictions, not that this means anything to a believer in special relativity theory. As was pointed out earlier if one ignores these data the reliance on pure special relativity theory turns out to be just another pile of pure scientific bullshit.

Geistkiesel

11. Originally Posted by superluminal
From the muons POV (travelling at .79c or whatever) the universe exists in a contracted state. What appears to us to be 15.6bly is, to the muon, only 9.6bly. The earth only travels () that distance to the muon.
The distance the Earth travels was not the issue here, it was the time on the muon's clock. In order for light to not reach the muon in it's contracted universe, the total time accumulated in the muon's frame must be less than that accumulated in the Earth frame. However, this is not what Special Relativity claims.

12. geist:

I have seen no information in this forum other than SRT claims that time dilation accounts for the muons reaching the planet surface
Well big G, since this thread is about accepted science and how we explain muon fluxes at the surface, then I guess you better star another thread dedicated to why that ain't so. Whaddya think?

13. The distance the Earth travels was not the issue here, it was the time on the muon's clock. In order for light to not reach the muon in it's contracted universe, the total time accumulated in the muon's frame must be less than that accumulated in the Earth frame. However, this is not what Special Relativity claims.
Ok let me think. I'll get back to it tomorrow.

Actually, I don't understand the problem as you state it.

14. Originally Posted by Janus58
It is not a conclusion, it is a intial condition of the test. The muon crosses the depth of the Earth's atmosphere as measured in both frames.

Janus58 there are some data needing explaining by someone with familiarity with SRT as these data are contradictory. See what you can do with this, ok?what does special realativity theory say about muons created at various levels of the atmosphere?I have seen nothing from SRT on this. How, or why does SRT ignore these kinds of experimental data?
I suppose it is, not by ignoring the data, rather the data is not sought out, is it Janus 58?

Why do you appear on this forum professing to offer anything other than what is expected from a robot?

Geistkiesel

15. Janus58,

If It were me, my answer to:

Why do you appear on this forum professing to offer anything other than what is expected from a robot?
Would be "Fuck you geistkiesel, and the fucking relativistic jackass you rode in on."

Just my opinion though.

16. by superluminal:

"The muon sees all distances and lengths that have relative velocity to it as contracted.

The earth sees all distances and lengths that have relative velocity to it as contracted.

In our rest frame, the muon is created 10000m up and must traverse that distance."
================================================== =============

Do you guys really not see the mistake here? 'The earth sees all distances and lengths
that have relative velocity to it as contracted.' Then an UNCONTRACTED distance is
stated, 10000m.

Surely you guys know that all you have to do to skew Special Theory results is to start the gedanken from the 'wrong frame'. Example:

The muon is created at 10,000 meters from the Earth through decay. (varies,of course). The muon sees the Earth clock as beating slower than its own. The muon lives a MEAN life (not half-life, a different thing) of 2.2 microseconds in its 'rest' frame,
and 'sees' the Earth's clock accumilate only a fraction of this time, about .13 microseconds, before it decays. The Earth 'sees' the distance to the muon as length
contracted, instead of 10,000 meters, the Earth observer sees the muon created at
about 600 meters. Special Theory blows up when starting the exercise from the 'wrong'
frame, even though STR states there are no preferred frames.

17. 2inq:

There's no mistake in superluminal's post. Both the muon and the Earth observer agree that the muon originates in the atmosphere right next to the (imaginary) altitude balloon with "Height: 10km" on it. The muon doesn't agree that there's 10km to the surface of the earth, however.

Your gedanken fails not because you start from the "wrong" frame, but because your setup doesn't match the conditions of the muon experiment: If the muon originates 10,000 muon meters away from the earth, it'll originate far outside the atmosphere, because the earth (and it's atmosphere) is length contracted.

The starting condition, however, was that the muon originated 10,000 Earth meters up in the atmosphere, not 10,000 muon meters. To interchange the two is to mix length measures from different frames, and that's a no-no.

18. Uh, no funkstar. When beginning the exercise from the muon's frame of reference,
the muon sees the Earth clock running slow. The muon DOES NOT see distance
contracted from this frame. Changing to the Earth's frame of reference, the distance
to the muon seems contracted. It is exactly opposite of starting from the Earth's frame
of reference, in which the Earth observer sees the muon's clock running slow, then
changing to the muon's frame of reference, the muon sees the distance contracted.

19. 2inq:

When beginning the exercise from the muon's frame of reference,
the muon sees the Earth clock running slow. The muon DOES NOT see distance contracted from this frame

20. 2inq, I'm sorry, but you're mistaken.

In one gedanken the muon originates 10,000 Earth meters from the surface of the earth. In the other gedanken the muon originates 10,000 muon meters from the surface of the earth. This is not the same thing. Can you see why? Think about the altitude balloon...

Also, of course the muon sees the Earth as length contracted. After all, in the muon frame the Earth is moving and so must be length contracted. And therefore the Earth's atmosphere, moving with the Earth, is also length contracted.

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