Re: heating and expanding

Ron Kean (
Wed, 31 Mar 1999 08:02:05 -0500

On Wed, 31 Mar 1999 16:37:28 +1000 Julian Leviston <> writes:
>Hi :-)


Most of the ideas that are in current science
>are based on theory. Theory in my definition of the word is unverified
>I don't understand how scientists have arrived at the fact that the
>universe is expanding if not simply from theory.
>And theory is guessing. I'd rather not accept guessings.

In common speech, the word 'theory' is often used to mean a guess or a conjecture. And those are among the dictionary definitions of 'theory'. People sometimes use the word 'theory' as in 'This is just a theory...' when they mean 'hypothesis', 'conjecture', 'tentative assumption', or 'informed guess'.

But in the context of the scientific method, a 'theory' is not just a guess. It is a well-developed explanation of a class of phenomena, an explanation which is experimentally testable, an explanation which can in principle reliably predict the outcome of a relevant experiment, and, usually, an explanation which is widely understood to be true within its proper context and area of application.

Examples include Einstein's Theory of Relativity, or Newton's Theory of Gravitation.

Ron Kean




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