Re: Search for Higgs Boson not dangerous.

From: Bjoern Feuerbacher (feuerbac_at_thphys.uni-heidelberg.de)
Date: 08/27/04 

Date: Fri, 27 Aug 2004 18:52:43 +0200

TomGee wrote:
> Bjoern Feuerbacher <feuerbac@thphys.uni-heidelberg.de> wrote in message news:<cgl5bk$bvh$2@news.urz.uni-heidelberg.de>...
>
>>TomGee wrote:
>>
>>>"Old Man" <nomail@nomail.net> wrote in message news:<DaydnV08J62AyLfcRVn-pA@prairiewave.com>...
>>>
>>>
>>>>Rather than an explosion of matter, the Big-Bang was / is an
>>>>explosion of space, and not at just one point, but at all points.
>>>>Local mass / energy exists in an inertial reference frame that
>>>>co-moves with the expansion.
>>>>
>>>
>>>So you believe that as the universe expands, space and all
>>>objects/systems in it move along with it as if fixed in the space they
>>>occupy?
>>
>>Yes, essentially (please notice that there are also so-called "peculiar
>>velocities"). That's what General Relativity says.
>>
>>Snip
>>
>>
>>>It seems the latter would be correct since
>>>objects/systems appear to be independently moving away from each
>>>other. If the former were true, that requires some sort of universal
>>>absolute force to impose itself upon all objects/systems in relation
>>>to the space they occupy, and in relation to all of space.
>>
>>Err, how does this follow?
>>
>
> In an explosion, matter flies outward from its center in all
> directions due to the impetus provided by the forces of the explosion,
> and such matter moves independently of the space it moves through. In
> a landmine explosion, e.g., the air through which the metal fragments
> fly does not expand or move along with them. In order for objects to
> move along with the expansion of space as if they are fixed in the
> space they occupy, something must fix them "in place" like a glue
> would fix ants on the surface of an expanding balloon.

The force which fixes them there is simply inertia.

>>>Such a
>>>force is not evident, but if you have a theory about it, let's have
>>>it.
>>
>>The theory which says that the universe "carries" objects with it as it
>>expands is called General Relativity.
>>
>
> Okay, twice now you have referred to GR as the basis for your beliefs,
> but you have not let me in on just exactly where I can find such
> information. Would you please quote me that part of GR which makes
> that statement so that I may learn it too? Thank you.

The geodesic equation of GR (that's the analogue of Newton's first law,
essentially - it tells us how things move as long as no forces act on
them) tells us that as long as no forces act on an object, its
coordinates will not change. Nevertheless, since the distance between
any two objects is given by a(t) * sqrt(dx^2 + dy^2 + dz^2), where a(t)
is the so-called "scale parameter" (I give here only the simplest
example, a flat universe; for the general case, read up on
"Robertson-Walker metric"), the distances between objects increases with
time, even if their coordinates stay the same.

How else would you call that than "space carries objects along with it"?
One could perhaps also say "object stay where they are, but the space
between them expands" - that has the same effect.

Bye,
Bjoern