Arcadian Functor

occasional meanderings in physics' brave new world

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Marni D. Sheppeard

Thursday, April 10, 2008

Achilles and the Tortoise

Zeno of Elea's lost book is said to have contained 40 paradoxes concerning the concept of the continuum. The paradoxes are mostly derived from the deduction that if an interval can be subdivided, it can be subdivided infinitely often. As an Eleatic, Zeno subscribed to a philosophy of unity rather than a materialist and sensual view of reality. This led to greater rigour in mathematics, since more emphasis was placed on logical statements than on physical axioms laid down arbitrarily on the basis of (inevitably deluded) experience.

Most famously, the paradoxes discuss Time as a continuum. If we have already laid out in our minds a notion of classical motion through a continuum, the infinite subdivisibility of Time must follow. But note the introduction here of a separation between object and background space. To the Eleatics, this is the source of the problem, not the mathematical necessity of infinity itself. By placing a fixed finite (relative to the observer) object in a continuum, we have allowed ourselves to ask questions about its motion which are physically unfeasible.

But the resolution comes not from concrete physical axioms about an objective reality, based as they are on the very prejudices that lead to paradoxes in the first place. Rather, it comes from refining the mathematics until its definitions are capable of quantitatively describing the physical problem correctly. We have known this for thousands of years, but do many physicists really appreciate this today?


Blogger CarlBrannen said...

Clearly I'm going to have to write a post on the Quantum Zeno effect / paradox.

April 10, 2008 3:44 PM  
Blogger Kea said...

Yeah, go on! I'm much lazier than you are.

April 10, 2008 4:47 PM  
Blogger CarlBrannen said...

And here it is.

And are you surprised to learn that the quantum Zeno effect goes away when the measureming device is included in the quantum system? And that this is done with density matrices?

April 10, 2008 5:28 PM  
Blogger Kea said...

No Carl. Not at all surprised.

April 10, 2008 5:32 PM  

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