The multiverse idea can be tested as I was previously arguing in
this thread, by partaking in a game of quantum roulette, although you'd have to be either very brave or very stupid to try it.
There is also a method devised by David Deutsch involving quantum computation and a self-conscious computer which would give an experimental difference between Copenhagen and Many worlds interpretations. Unfortunately, I can't remember the exact details and I don't have the book in which I read it with me.
Having said that, there are no realistic ways of testing for the multiverse, so I agree with you that it is speculation, albeit interesting.
Personally, I don't see why the multiverse concept is any more ludicrous than the concept of an infinite Universe. Would an infinite universe be described as "an interesting speculation". Aren't a multiverse and an infinite universe almost identical in the possibilities they allow?
Here's a good debate on the topic:
Are parallel universes equally real? | WIRED
PE
[This message has been edited by Primordial Egg, 04-06-2004]
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