Do atoms exist?

Robosapien said:
It's not that straightforward - even if one particle is fired through a pair of double slits you still get a diffraction pattern. How does that happen if it's, as you imply, particles exhibiting wavelike behaviour, with the wave equation simply giving position.

The act of observing the position actually changes the system. So the wavefunction only really tells us what the system will be like once a measurement is made - we don't know for certain what the system is like before we fire something in there and screw things up.
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The wavefunction is a wave of probability, so the photon of light is spread over an undefined area. You can think of the wavefunction travelling through the slits, diffracting and then the resulting wavefunction will produce an intereference pattern, however this won't be visible for just one photon, it can't be detected at two places. If you were to fire single photons one after the other, then the pattern would form.
 
Six7th said:
The wavefunction is a wave of probability, so the photon of light is spread over an undefined area. You can think of the wavefunction travelling through the slits, diffracting and then the resulting wavefunction will produce an intereference pattern, however this won't be visible for just one photon, it can't be detected at two places. If you were to fire single photons one after the other, then the pattern would form.
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The wavefunction is a mathematical expression which represents the probability of the electron's position.
So I can think of the 'probability of the electron's position' as having passed through both slits?
That's wrong, the electron itself passes through both slits, otherwise you wouldn't get that pattern (or the one electron ending up at a particular point in that pattern).
You are implying that the electron carries with it some invisible extra information which interacts with itself giving resultant position, which is somehow divorced from the reality where the particle itself just goes through one slit. That's not the case.
It's not a particle exhibiting wave-like properties, nor the reverse. It's both. Which is why it's called a 'duality'.

None of this proves that atoms don't exist however, so I don't know why I'm bothering.

Edit:- Although what it does suggest, is that sometimes a single model/description does not always adequately represent the reality.
 
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Just to make a point, years ago, a completely different "model" existed. It was then proved redundant.

Same thing could potentially happen tomorrow.

My Physics teacher defined science in a very good way. I just can't remember it.

Something along the lines of "Science is the belief of ... ... ... due to the presence of repeatable experimentation results".
 
AshD93 said:
Just to make a point, years ago, a completely different "model" existed. It was then proved redundant.

Same thing could potentially happen tomorrow.

My Physics teacher defined science in a very good way. I just can't remember it.

Something along the lines of "Science is the belief of ... ... ... due to the presence of repeatable experimentation results".
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I hear that a lot. "All of modern science could be overturned tomorrow." I mean, it's technically correct - anything is 'possible', but people often use it in such a way as to imply that as a result of this modern science is worthless and without evidence.
 
AshD93 said:
Just to make a point, years ago, a completely different "model" existed. It was then proved redundant.
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Probably not redundant at this stage, unless we find out we're trapped in the matrix, or it's all a gigantic conspiracy by the lizards.

We've had very useful, proven results, so not exactly redundant. Unless you're talking about much older universally accepted at the time theories, like a flat earth or faith healing. Some older theories may even be more useful if they apply to special cases.
 
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Lots of the old technically incorrect stuff is used. How many people put the gamma factor in the speed equation, there isn't any reason to for most speeds as the difference is negligible. Same with most of classical physics, some of it is technically wrong but gives good enough accuracy.
 
Dimple said:
The most mind blowing fact I've ever heard is that if you take out all the empty space out of every atom of every person who has ever lived on the Earth, you could squash them all into a sugar cube.
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Almost, a bit more than current population would fit in a sugar cube, based on the same calculations they use in the wiki reference for that piece of info, you'd need 14 sugar cubes for all the people that have ever lived :)
 
I did my own calculations, if you compressed everybody that had ever lived down to the density of a neutron star they would all fit on a tablespoon. Although i think the population figures i used might have been from the 80's, shouldn't make that much of a difference...
 
bam0 said:
Almost, a bit more than current population would fit in a sugar cube, based on the same calculations they use in the wiki reference for that piece of info, you'd need 14 sugar cubes for all the people that have ever lived :)
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Did they take into account Pauli Exclusion principle?

Depends what is meant by empty space. Highest density we know of is singularity.
 
semi-pro waster said:
I'd probably not recommend that approach as the most beneficial way to go about the issue as you might be being unduly offensive but you're right that it's worth bearing in mind when people start to expound theories outwith their area(s) of expertise that they could well be complete bunkum.
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Not saying he's right but his stance is one in which he is adopting a anti-realist or antirealism v realism perspective so I wouldn't necessarily argue he is just talking off the top of his head the way in which the OP has said either.:) wise advice regardless.
 
Mason- said:
**** you.

I never said what I was saying was correct. I'm not a scientist. How dare you judge me on one thing I say. Do one and get off your high horse.
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Well, just a suggestion here; if you're "not a scientist" then try to refrain from making concrete statements about things that you clearly do not understand? That might save you from getting your knickers in a twist. :rolleyes:
 
Sefirosu said:
Bear with me...

My old philosophy teacher said that he didn't believe atoms actually existed; he said that it was just a convenient way to describe the behaviour of matter, and that they didn't exist as they were described to as such, and furthermore atoms have never been directly observed.

Obviously, I'm assuming this is BS, but what is the main evidence that atoms, electrons and so forth exist?
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I hope you didn't pay for that degree.
 
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