The Zeno effect

[PRC1964]

It seems that in the future computers will produce results without needing to be turned on. We're doomed, one day they may even invent an automatic tape changer and Milan will be destitute.

http://www.newscientist.com/channel/...25405.700.html

A quantum computer program has produced an answer without actually running.

I also liked this:

A non-running computer produces fewer errors

[threaded]

Time is continuous, and time measurement can be discrete, but they are different things. Much like molecules jumping about can be said to be at 25C, the jumping about is a thing different to temperature.

One of my problems with quantum physics is quantization of time, i.e. that the functions used, such as differentiation and integration, rely on an assumption that a time span can be allowed to become so small that although not actually zero it can be treated like zero.

This is utter nonsence and leads to rubbish like Zenos paradox.

And where a switched off computer gives an answer before you ask it.

[bogeyman]

Time is continuous, and time measurement can be discrete, but they are different things. Much like molecules jumping about can be said to be at 25C, the jumping about is a thing different to temperature.

One of my problems with quantum physics is quantization of time, i.e. that the functions used, such as differentiation and integration, rely on an assumption that a time span can be allowed to become so small that although not actually zero it can be treated like zero.

This is utter nonsence and leads to rubbish like Zenos paradox.

And where a switched off computer gives an answer before you ask it.

Oh dear - the Great Threaded "has a problem with" quantum physics.

I think the leading lights in the world of physics need to be informed of this.

Anyway, why is Zeno's paradox 'rubbish' exactly (assume you mean the Achilles paradox - he had a few others up his sleeve)?

Surely it is quantization that resolves Zeno's paradox (i.e. distances/times cannot become infitinely smaller and smaller).

[threaded]

Lets try a simpler example to show my point: When a ball is thrown into the air, the current mathematical model says that at some moment between going up in the air and coming back down the ball is stationary.

I say that is bollox.

Simple really.

[sasguru]

Lets try a simpler example to show my point: When a ball is thrown into the air, the current mathematical model says that at some moment between going up in the air and coming back down the ball is stationary.

I say that is bollox.

Simple really.

Why do you say it is bollox?

[bogeyman]

Lets try a simpler example to show my point: When a ball is thrown into the air, the current mathematical model says that at some moment between going up in the air and coming back down the ball is stationary.

I say that is bollox.

Simple really.

As for throwing a ball up in the air it decelerates due to gravity. At some point, the velocity of the ball in the upward direction will be zero (stationary) due to the effects of that deceleration. The ball will then fall back to Earth, accelerating due to the effects of gravity.

This is simple Newtonian physics man! What's the problem?

Of course, if you want to expand the argument to include general relativity (i.e. is the ball stationary from a particular observer's POV then carry on).

Now, lets get back to why you think Zeno's paradox is 'rubbish'.

[threaded]

Why do you say it is bollox?

Because it is an artifact of the mathematical model.

Consider bogeyman walking down the railway line at 5 kph, a train coming the opposite way hits him at 200 kph.

i.e. he goes from 5 kph to -200 kph.

So according to the model when he is stuck on the front of the train at some point he is doing 0 kph, hey, but he is stuck to the front of the train, is that not also doing 0 kph at that time?

[bogeyman]

Because it is an artifact of the mathematical model.

Consider bogeyman walking down the railway line at 5 kph, a train coming the opposite way hits him at 200 kph.

i.e. he goes from 5 kph to -200 kph.

So according to the model when he is stuck on the front of the train at some point he is doing 0 kph, hey, but he is stuck to the front of the train, is that not also doing 0 kph at that time?

If you have trouble with that - I suggest you don't stress your brain with too many paradoxes.

Read a little bit about General Relativity!

Funny, Einstein used trains quite a bit in his 'thought experiments' to illustrate relativistic effects. You might be able to grasp that.

i.e. he goes from 5 kph to -200 kph

Yes, indeed I do! In this unfortunate enounter with the Threaded Express, a spot on the end of my nose will go from 5 to -200 kph according to an observer standing (at 0 kph) on the trackside.

This will, however, not happen instantatiously. My mass and velocity will counter the trains mass and velocity. I will take some kinetic energy from the train, and it will add (a lot more) kenetic energy into poor me.

The aforesaid spot on my nose will rapidly decelerate, stop, and begin accelerating in the direction the train is travelling. But, as I said, this happens over a period of time (albeit a short one).

What do you fail to understand here, Threaded?

Did you never do a Physics O-Level/

[threaded]

Hey, don't get me wrong, I teach that stuff to my students so they can pass exams.

It's just that I don't believe in it, cause it's all mathematical bollox made to fit the observations. None of it has made any truely new predictions, just confirmed stuff already observed, and often times it has been twisted some more to fit the observations.

An awful lot of these people who believe in quantum theory are just as bad as these fundamentalist xtians, and potentially do even more damage to scientific progress.

[bogeyman]

Hey, don't get me wrong, I teach that stuff to my students so they can pass exams.

It's just that I don't believe in it, cause it's all mathematical bollox made to fit the observations. None of it has made any truely new predictions, just confirmed stuff already observed, and often times it has been twisted some more to fit the observations.

An awful lot of these people who believe in quantum theory are just as bad as these fundamentalist xtians, and potentially do even more damage to scientific progress.

Sorry mate!

Did you say you TEACH this?

If so, I can only pity your students?

What are you qualifications exactly?