Re: Reaching Light Speed,

From: Bjoern Feuerbacher (feuerbac_at_thphys.uni-heidelberg.de)
Date: 09/30/04 

Date: Thu, 30 Sep 2004 11:01:03 +0200

jahn wrote:
> "Bjoern Feuerbacher" <feuerbac@thphys.uni-heidelberg.de> wrote in message news:cjeffe$a3t$1@news.urz.uni-heidelberg.de...
>
>>jahn wrote:
>>
>>>"Bjoern Feuerbacher" <feuerbac@thphys.uni-heidelberg.de> wrote in message news:cje8sn$8hj$1@news.urz.uni-heidelberg.de...
>>>
>>>
>>>>jahn wrote:
>>>>
>>
>>[snip]
>>
>>
>>
>>>>>Deflection plates (since we want to ignore spin [shrug]) co-moving with a particle
>>>>>can accelerate the mass to near c wrt the plates.
>>>>
>>>>Err, if the plates are co-moving with the particle, then how can the
>>>>mass move with almost c wrt the plates?
>>>
>>>Put identical charges on the plates.
>>
>>How does that help? Again: if the plates are co-moving with the mass,
>>then how can the mass move with almost c wrt the plates?
>
> Think of it in two steps. First the plates and the particle are accelerated to 0.8 c wrt the lab by using Einstein rail car.
> Secondly the plates are chaged to further accelerate the particle an additional 0.5 c. wrt the rail car.

So the plates are in the second step no longer co-moving with the mass?

Anyway: the result will be that the plates move wrt the lab
(as measured in the frame of the lab, or of the plates) with 0.8c,
the mass will move wrt the plates (as measured in the frame of the
plates, or of the mass) with 0.5c, and the mass will move wrt the lab
with 1.3/1.4 c, which is about 0.93c (as measured in the frame of the
lab, or of the mass).

[snip]

>>>>>The particle's motion wrt the lab imposes no constraints on the
>>>>>ability to further accelerate the particle wrt the lab.
>>>>
>>>>Wrong. It does indeed impose constraints, since the inertia increases.
>>>
>>>So how do the plates know this?
>>
>>Before I can answer that, you probably should first tell me how
>>the plates can be co-moving with the mass, and at the same time,
>>the mass is moving at 0.5c wrt them. Doesn't that somehow sound
>>contradictory to you?
>
> No. It sounds more like your previous argurment fell apart when
> electrostatic charge replaced the Lorentz force of the magnets you
> were using.

What previous argument do you mean? Where did I use any magnets???

[snip]

>>>>No, this never happens. The velocity of one bunch wrt to the other
>>>>(as measured in the frame of one of the bunches) is *not* the same
>>>>as the difference of the velocities of the two bunches (as measured
>>>>in the lab frame).
>>>
>>>Then colliders are a waste of money, Eh?
>>
>>No. How does that follow, IYO?
>
> The purpose of a collider is to overcome the speed of light
> limitation wrt the lab frame.

No, it isn't. Why on earth do you think so?

> You are suggesting that colliders can't
> really work because a limit of c will apply to one bunch as
> observred from the other bunch.

Such a limit indeed applies. And that does not in any way hinder the
working of the collider. Why on earth do you think so?

Bye,
Bjoern

Relevant Pages

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  • Re: Reaching Light Speed,
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