I Need Brian Cox.

[Pumpkinstew]

Um, well, if you're happy with idea that matter and energy are equivalent that's always a good place to start.
Then you have to start thinking of particles as not being finite. Instead they're little bundles of waves which have a probability density which localises the vast majority of that energy in that one region of space (and time).
This wiki entry is a bit formal but has a useful graphic

That gets you to the interference pattern (wavelike behaviour) being created by particles. And other phenomena such as quantum tunnelling and Hawking Radiation.

Then the thorny bit - how does observing the wave/particle cause it to behave more like a particle than a wave? Especially as it may have passed through the slit you aren't observing!
There isn't a definitive answer that I know of. Relational Quantum Mechanics has a bash at explaining it. But really it comes down to saying the same thing - by observing the quantum system you force it into a state instead of a range of possible states at the point in time and space when it is passing through the slits. Schrodingers equation is time and space dependent remember.
Importantly though in RQM the observer becomes part of the quantum sytem, and different observers may see different, but still correct, outcomes because the equation continues to evolve with time.

It's worth pointing out though that various detectors and particles have been used in the double slit experiment and the level to which the interference pattern is disturbed varies. this strongly suggests that the fundamental interation between the detector and the wave/particle at the point in space time at which it passes through the slits is what varies the strength of the interference pattern.

The QM I did at university is a hazy and distant memory though and i may have gotten totally the wrong end of the stick. If you were still in Exeter I could have suggested a professor who would know for sure. I may have an old textbook at work still. I'll have a thumb through it tomorrow and see if it becomes any clearer.

[Pumpkinstew]

Originally Posted by Mark

What no mention of Schrödinger's cat?

It does illustrate the RQM way of looking at things quite nicely.

Before the box is opened, the cat, by nature of it being alive or dead, has information about the state of the apparatus

Poor cat.

[Mark]

Originally Posted by Pumpkinstew

Poor cat.

Of course, it seems that Schrödinger completely neglected the obvious solution to the problem - the zombie cat.

[Will]

One of my favourite books - "In Search of Schrodinger's Cat" by John Gribbin.

[Pheebs]

Okay... well the brain is a bit more accepting of the comments here! It makes me feel slightly better that it's all a bit mind boggling to all!

I like Schros Kitty Cat. I understood all of that (I say understood because I looked at it years ago and seemed to absorb it quite comfortably without my mind exploding. I'm sure I need a refresher read of it all).

I think it frustrates me that I have to just *accept* things and not be able to understand why!

Stew - Darnit! I am in Exeter soon but on business! Boo hiss!

Thanking you people and your brain strains! I've just started reading Stephen Hawkings latest book but have paused due to the whole CERN discovery. I have this fear of reading his book, understanding it for the first time ever only to be told it's all messed up and wrong! Hahahaa!

Something tells me my prophecy of me being able to comprehend it in the first place is a slim chance of occurring!

[Creature]

Originally Posted by Pheebs

Mc Chrispycoates suggested it was magic. Which I kinda liked.

I still stand by this. That, or pixies.

[volospian]

Originally Posted by Pheebs

Something tells me my prophecy of me being able to comprehend it in the first place is a slim chance of occurring!

I doubt many people can really, fully, comprehend it all. We have snippets of information that generally explains some things in a very simplistic manner, such as schrodinger's cat but the deep stuff is, funnily enough, all relative.

You can't really get your head around D until you fully understand the concept of C on which it is built, and you can't fully understand C until you really get B, and even that is hard to understand until you know all about A.

I mean, think about gravity. You think you understand gravity, it's what makes apples fall out of trees and so on, but what is gravity? What is going on to make things pull themselves together, or spin around each other in space. The earth, for example, stays in a faily short orbit around the sun, and yet comets, which are much smaller and presumably much less dense seem to have orbits that take them way out as far as Pluto... so, if the sun can affect bodies that far out... how does the earth stay where it is and not crash into the sun? I know acceleration comes into play, but how are gravity and acceleration linked? Is acceleration a "force" like gravity? What's going on out there??

It's like trying to imagine the size of the universe, or what came "before" it. The accepted answer seems to be "nothing" as there was no "time" prior to the big bang, however, one model of the universe allows for expansion to stop and gravity to pull everything back into a "big crunch". This *may* be followed by a "big bounce" as everything is compressed until it reaches a point where the singularity explodes again into another big bang, so, based upon this theory, the universe could have formed and collapsed billions of universes before. We all may have lived our lives billions of times already...

It's also boggling to imagine what comes after it. Some theories suggest a "big rip" where the universe carries on expanding at an increasing rate until the expansion rate becomes infinite and the universe simply rips itself apart. If that's the case... what will it expand into? What is "beyond" our universe? It's hard to concieve of an expanding universe with nothing to expand into. The infinite is very difficult to get your head around...

[Pumpkinstew]

Originally Posted by volospian

I mean, think about gravity. You think you understand gravity, it's what makes apples fall out of trees and so on, but what is gravity?

The standard model attempts to unify the four (or three depending on who you ask) forces of gravity, electroweak and strong nuclear. The last two are exerted by the exchage of particles. The supposition is that gravity should also be exerted by an exchange particle (the graviton) but it hasn't been observed and so the search for a GUT (grand unified theory) goes on.

Originally Posted by volospian

I know acceleration comes into play, but how are gravity and acceleration linked? Is acceleration a "force" like gravity?

Yep, it comes into play. F=ma according to Newton. And this non-relativistic version is super accurate for describing how celestial bodies move around.
Acceleration isn't a force in the same way as gravity. It's the result of an unbalanced force acting on a mass.

Originally Posted by volospian

one model of the universe allows for expansion to stop and gravity to pull everything back into a "big crunch".

Largely out of fashion now since it's been shown that the rate at which the universe is expanding is increasing not slowing down. No-one knows why this is. It's what the search for Dark Energy (ooooh, sounds spooky) is all about. Explaining the expansion of the universe.

[volospian]

Originally Posted by Pumpkinstew

The standard model attempts to unify the four (or three depending on who you ask) forces of gravity, electroweak and strong nuclear. The last two are exerted by the exchage of particles. The supposition is that gravity should also be exerted by an exchange particle (the graviton) but it hasn't been observed and so the search for a GUT (grand unified theory) goes on.

I've been reading lately about the superfluid vacuum theory, and while I don't pretend to understand it fully (or even partially ) it makes more sense to me than the concept of gravitons.

Yep, it comes into play. F=ma according to Newton. And this non-relativistic version is super accurate for describing how celestial bodies move around.
Acceleration isn't a force in the same way as gravity. It's the result of an unbalanced force acting on a mass.

Well, ok... it is described as not being a "force like gravity", but the effects are both so similar... both the addition of "gravity" and the addition of "acceleration" increase mass, and both dilate time... is it not possible that acceleration is gravity, and vice versa?

I mean, an object at rest is still potentially subject to some kind of gravity, wherever it is.

To accelerate an object we need to add some kind of "force" which I presume is a transfer of energy? Adding energy should increase its mass anyway, shouldn't it? and increasing mass also increases gravitational pull, doesn't it, so adding energy increases gravity?

so... what we term "acceleration" is simply the "addition of gravity" above and beyond the local gravity field caused by increasing the relative mass by the application of energy... sort of thing... ?

Largely out of fashion now since it's been shown that the rate at which the universe is expanding is increasing not slowing down. No-one knows why this is. It's what the search for Dark Energy (ooooh, sounds spooky) is all about. Explaining the expansion of the universe.

Yep, that's why I included the "big rip" theory...

[volospian]

ps...

Mrs. Schroedinger to Mr. Schroedinger: What the hell did you do to the cat? It looks half dead!