In my view Physicists spent the first half of the 20th cent exposing contradictions and the second half covering them up with ever more convoluted 'theories of everything'

Special Relativity works fine. There are no known inconsistencies.

General Relativity cannot overcome what in mathematics is known as the 'hairy ball theorem'
It is a basic tenet (postulate) of both relativities that there are no 'special points' which we can use as a point of reference or origin.
General Relativity introduces the idea of curved space on a 4 dimensional manifold, a non euclidean geometry.
The hairy ball theorem basically states that euclidean geometry is the only geometry that does not contain at least one 'critical point' -Such a point is special and couls be used as an origin.

Anyway back to Physics. You will note that I have consistently avoided having time in my equations.
By symmetry the wave equation could equally well be separated and solved for a time axis.

If this is all there is to matter, as quantum mechanics would have us believe, then the solution along a time axis would be a complete history of a particle for all time.

In other words we live in a completely deterministic universe.

Once again I stress the importance of not blindly or slavishly using mathematical techniques in the physical world.

A couple of points about the speed of light and functions.

Firstly we have discussed the speed of light before and its position vis a vis relativity.

http://forum.allaboutcircuits.com/showthread.php?t=6779&highlight=hydraulic+jump

Secondly

Do not suppose that the statements 'the function equals zero and 'the function does not exist' ... both for some value of x are the same.

Far from it.

The average of -3, 10 an -7 is zero. All the components and the average exist. Zero is a perfectly respectable number.


But

Solutions to the equation y = arcsin(x)


do not exist outside the range -1 < x < 1
and cannot be replaced by the number zero.

 

I am no expert on phonons but I wonder if they need a transverse component?

Sound is transmitted through both liquids and gasses. However fluids cannot support S waves, a fact exploited by seismologists.

I do not subscribe to the view that the Minkowski 4D space-time universe is wholly accurate, any more than Mercator thought his map was. It is a model, a bit like a cartographic map, with at least one point of gross distortion of reality, by the aforementioned hairy ball theorem.

A mercator map has the useful property that bearings read from it are true. However the distortion of distance is infinite at top and bottom of the map.

 

In other words we live in a completely deterministic universe.

But quantum mechanics also involves the uncertainty principle, and the idea that only when we actually make a measurement, is it actually "determined".

Doesn't that contradict determinism: randomness does exist based on quantum dynamics?

-blazed

 

Are you talking about tachyons rather than neutrinos Billo? I was under the impression neutrino velocity was just fractionally less than c..
If it is tachyons, then they are just theoretical particles that would carry imaginary mass, and can move only faster than c, requiring infinite energy to slow down to c.. They are just the result of allowing the sqrt of a negative value in the denominator of the SR gamma transformation..
Sorry if I'm confused and everyone knew that already..

 

uncertainty principle

How does this apply to calculations rather than measurements?

We are always at liberty to specify
Let there be a particle of mass m, at a point p, and velocity v....... A bit like an exam question...

At the end of the 19 cent physicists thought that given that statement and the then laws of mechanics it should be possible to predict the entire course of the rest of that particle's history and by implication all the other particles in the universe. It was called the 'clockwork universe'.

This deterministic approach was beloved of the SCiFi writers of the early 20 centuury, perhaps epitomised by the Doc Smith Lensmen series. Scifi also reflected the development of logic theory at this time 'the worlds of Null A'

New (at that time) experimental data that eventually led to quantum mechanics ran counter to this idea. It was also opposed on religous grounds.

At the end of the 20th century we are alleged to be close to the grand unified theory that will explain and predict everything (in physics). Do you see a pattern emerging?

The question is: given my particle above what do the calculations of its future physical properties mean if we apply clasical physics, quantum mechaincs, relativity, quantum chromodynamics etc or some combinations of these.

 

Learning about the universe is like collecting water in a plastic shopping bag.. There is bound to be a drop of water/knowledge that splits the bag open and forces you to take a step back to clean it all up..

 

How does this apply to calculations rather than measurements?

We are always at liberty to specify
Let there be a particle of mass m, at a point p, and velocity v....... A bit like an exam question...

At the end of the 19 cent physicists thought that given that statement and the then laws of mechanics it should be possible to predict the entire course of the rest of that particle's history and by implication all the other particles in the universe. It was called the 'clockwork universe'.

This deterministic approach was beloved of the SCiFi writers of the early 20 centuury, perhaps epitomised by the Doc Smith Lensmen series. Scifi also reflected the development of logic theory at this time 'the worlds of Null A'

New (at that time) experimental data that eventually led to quantum mechanics ran counter to this idea. It was also opposed on religous grounds.

At the end of the 20th century we are alleged to be close to the grand unified theory that will explain and predict everything (in physics). Do you see a pattern emerging?

The question is: given my particle above what do the calculations of its future physical properties mean if we apply clasical physics, quantum mechaincs, relativity, quantum chromodynamics etc or some combinations of these.

Yes, we can claim in physics, given a particle p with position x, and velocity v, etc., etc.. But what does that have to do with saying whether or not the universe is deterministic?

The uncertainty principle doesn't just say we can't measure the position and velocity of a particle (or any other two opposing variables), but those two variables don't even exist at the same time. Furthermore, until we measure one of them, they are only in a quantum limbo. That's why Schrodinger's wave equation is only probabilistic.

It boils down to the fact that the universe at the subatomic level is literally random, which disputes determinism. Causality still applies, but determinism is not possible in a universe that contains true randomness. We can't predict exactly how the universe will act in the future if there is a random component involved.

-blazed

 

The question is: given my particle above what do the calculations of its future physical properties mean if we apply clasical physics, quantum mechaincs, relativity, quantum chromodynamics etc or some combinations of these.

Assuming classical modeling is at all relevant for your hypothetical particle, then classical physics would determine future properties to varying degrees of accuracy depending on the system you're looking at, relativity would yield the same general result, but more accurately, and since m is large enough that classical physics applies, using measurement scales appropriate for a particle of that size, quantum mechanics would yield a probability spread so tight the solutions would appear to be definate rather than a range of possibilities like you would see if the particle was so small that classical physics didn't provide anything sensible..

Edit: Regarding the accuracy, in extreme gravitational fields Newton's version doesn't perform to well.. There was a problem understanding the orbit of Mercury until GR was applied.. In flatter spacetime though, Newton provides pretty much the same result as GR with a fraction of the effort..

 

but those two variables don't even exist at the same time.

I would be interested to see your reasoning in support of this claim.

 

I would be interested to see your reasoning in support of this claim.

The way I phrased what I was trying to say doesn't make any sense. I take it back. I apologize.

A friend and I had a long conversation recently about determinism, which lead to me claiming that quantum mechanics shows randomness, which lead to him trying to claim the possibility of the hidden variables theory, so I have been delving into trying to figure out exactly how to explain to him the details of bell's inequalities and aspect's experiment, which proved that the uncertainty principle and quantum mechanics are true, and that they are not as EPR (Einstein, Podelsky, and Rosen) put it, incomplete.

But, to suggest that what I said, that the variables don't exist, is stupid, and would discredit any reasonable experiment of them. In fact, the first point bell makes, is that they DO exist, and must, because when you have two electrons (for example) defined by the same schrodinger wave equation (let's say they originated from the same radiating particle, or bounced off each other), then if you read one of their spins, the other will ALWAYS have the opposite.

And yet, there is a quantum entanglement that forces you to still not be able to know more than one of the associated variables...

But, alas, it seems I had only briefly read of the experiment and its implications in a book by Brian Greene, so I didn't really understand how it worked... and now I'm still trying to struggle with figuring that out... so I can explain it to him. Honestly, I was highly considering posting about it on the forums in this section, but then I finally found the original papers, and a few others talking about them, which shed light on some previously mysterious aspects. Still, it's a work in progress.

I can share with you guys what I have so far, since it would actually be right on topic, if you would like.

-blazed

Edit: about the conference call you mentioned, I only have a cell phone, so I don't think that's possible... but I'm curious if phone lines can perhaps work in tandem with something like skype perhaps... or if I'll ask the lab I work in to let me use their phone. Normally they would say yes, but if it's for a long distance, lengthy phone call, I'm not so sure.

 

Its not that the variables don't exist, its that discrete measurable values of them do not exist.. No matter how we look at them..
One thing I hear ppl say alot is that it is impossible to know the exact state of an electron at any given time.. This isn't true, we can know the exact state, what we can't know is the exact position or velocity, or energy and time of measurement.. Within those two pairs of variables, the more accurately you measure one, the less accurately you can know the other.. In a hypothetical situation where you could have an exact value, the complementary value would be infinitely unknown..

 

The Mach-Zehnder interferometer is an interesting practical demonstration of wave/particle duality as it forces a particle to exhibit firstly purely particulate behaviour then purely wave behaviour.

Have you seen the book referred to in post#28.

This is a wonderful compendium of this, Bell's inequality, EPR and much much more.
Penrose devotes a whole chapter (CH29) to the uncertainty principle.

 

The Mach-Zehnder interferometer is an interesting practical demonstration of wave/particle duality as it forces a particle to exhibit firstly purely particulate behaviour then purely wave behaviour.

Have you seen the book referred to in post#28.

This is a wonderful compendium of this, Bell's inequality, EPR and much much more.
Penrose devotes a whole chapter (CH29) to the uncertainty principle.

I've seen it in a book store before, but I know that's now what you meant.

I will probably try and look for it pretty soon. I wonder if it could be in my school's library... *goes to do an online check*

-blazed

Edit: It's there! And available... So yes, I'll be signing that book out today... sweet.

 

We'll see you in a decade then, when you've finished reading. M-Z is on page 515.

 

We'll see you in a decade then, when you've finished reading. M-Z is on page 515.

I have already read about the M-Z experiment and its results, in both books on my own and in previous classes.

I forgot actually to go to the library today, so I'll have to do it sometime next week I think. But mostly, I'm probably not going to read the whole book, just look at specific portions. Too much of the book is probably material I'm already familiar with for me to have the patience to read it all over again.

-blazed

 

Wow, this thread is taking off! Good, interesting stuff.

My last post did not show up. I guess I neglected to submit it.

I'm home from my road (air) trip and I just picked up an Acer Aspire One. Time to play!

Anyway, I can set up the con call next week. Anyone interested in joining, let me know and I'll PM you the toll-free acces number and the pin.

Bill

 

Wrong thread. Silly me.