I just finished a book about the mysteries of modern science, and one of the questions raised was 'Does there exists an objective reality?'

The arguments presented were all qunatum-mechanical in nature, and while it made for fascinating reading, I'm not sure I fully understood the conclusions reached (which was that an objective reality does in fact exist).

When struggling with quantum mechanics, Einstein once stated "Do you really think that when we look away from the moon, it disappears?" (or something to that effect) While this argument may be somewhat naive (since quantum objects are much more subtle), it raises a good point. Does observing something give it reality?

One theory advanced is that it is the consciousness of the observer that gives the object reality. Interesting.

What about the wave equation? This equation claims to give a probabilistic account for the position/momentum information of a particle at all instances when it is not being obeserved. When it is observed, the wave equation collapses into one reality. So if the particle is never observed, does it ever in fact come into existance?

Another interesting point raised, was the fact that a radioactive atom observed withing subsequent 'Zeno' times can be prevented from decaying. This blew my mind.

Another question I have, is regarding 'observing' something. How does the quantum system know it's being observed? The following variation of the double slit experiment really intrigued me (I think R.P.Feynman did this):

As the electron went through the slit, they were microscopicly tagged - so that we would be able to deduce which slit the electron went through--, in such a manner that did not interfere with the particle. But when this happened, the interference pattern disappeared on the screen, and the electrons started behaving like particles. However, an apparatus was set up between the slits and the screen, which would un-tag the electrons -- so that we would no longer have any knowledge of which slit they went through-- and the interference pattern returned on the screen (electrons behaving as a wave).

What does this mean? How did the system know that the observer had no possible way of knowing its path when the un-tagger was turned on?

Also, can someone explain 'consistent histories'.

I think this quantum mechanics stuff is really interesting...if I could only get my head around it!

dvst8