Freethought & Rationalism Archive

FairFiend · 02-02-2003, 08:26 PM

Thanks tk

I don't know if I'd call them "mythical" concepts, but your explanation helped. Now I know why I didn't go into physics.

For a mintue there I was about to become an agnostic.

Defiant Heretic · 02-03-2003, 12:51 PM

Just because something possesses the traits of two different things doesn't mean that it's self-contradictory.
There�s a difference between �A and B� and �A and not A�.

In case anyone reading this thread is a programmer, this shows what I'm talking about.

Code:

#include <stdio.h>
int main(void)
 {
  int a,b;//1=true, 0=false
  for (a=0;a<=1;a++)
   {
    for (b=0;b<=1;b++)
     {
      if (a&&b) printf("\n\nTest1 Successful\na=%i\nb=%i",a,b);
      if (a&&!a) printf("\n\nTest2 Successful\na=%i\nb=%i",a,b);
     }
   }
  getchar();
  return 0;
 }

Shadowy Man · 02-03-2003, 12:58 PM

Quote:

Originally posted by tk

We now also know that electrons are not idealized particles. Electrons can actually `cancel' each other out in certain cases, like waves can cancel each other out. But we know that idealized particles don't `cancel' each other out.

I think this statement is a bit misleading. Can you tell me in what instance you think electrons are "cancelling each other out"?

jj · 02-03-2003, 01:54 PM

Quote:

Originally posted by Shadowy Man
I think this statement is a bit misleading. Can you tell me in what instance you think electrons are "cancelling each other out"?

You can see interference patterns just like you can with light.

Shorter wavelengths to be sure.

At least shorter than most photons, there's a bit of energy there.

Shadowy Man · 02-03-2003, 02:11 PM

Quote:

Originally posted by jj
You can see interference patterns just like you can with light.

Shorter wavelengths to be sure. At least shorter than most photons, there's a bit of energy there.

Yes, you can get "interference" patterns with electrons. But this is not because they are canceling each other out.

If you perform a "two-slit" experiment with electrons what happens is that the wave nature of the electron interferes with the slits, not with other electrons.

jpbrooks · 02-04-2003, 01:43 AM

Quote:

Originally posted by FairFiend
I may be wrong, but entropy is a property of matter. Light is made up of oscillating electric and magnetic fields at right angles to one another. I think the analogy doesn't hold. I don't see how entropy would apply, but nice thought.

I may be wrong myself. But I always thought that the spreadng out of a non monochromatic light beam as it travels through space is a result of entropy.

On the matter of contradictions, assuming that our (real) world can allow the existence of entities of any kind with actual (not merely apparently) contradictory attributes doesn't really help existence arguments because there would be then no basis left on which to rule out the denial of any existence (or nonexistence) claim.

John Phillip Brooks

FairFiend · 02-04-2003, 06:14 AM

Quote:

Originally posted by jpbrooks
I may be wrong myself. But I always thought that the spreadng out of a non monochromatic light beam as it travels through space is a result of entropy.

Found this site which might clear things up.

http://www.entropysimple.com/

"Entropy measures how much energy is dispersed in a particular process (at a specific temperature)."

I would assume that as far as thermodynamics are concerned "process" would refer to a chemical reaction and "at a specific temperature" would be problematic for light since I'm pretty sure it's unaffected by temperature.

Quote:

Originally posted by jpbrooks
On the matter of contradictions, assuming that our (real) world can allow the existence of entities of any kind with actual (not merely apparently) contradictory attributes doesn't really help existence arguments because there would be then no basis left on which to rule out the denial of any existence (or nonexistence) claim.

Good point. Let's cross our fingers.

jpbrooks · 02-04-2003, 09:59 AM

Quote:

Originally posted by FairFiend
Found this site which might clear things up.

http://www.entropysimple.com/

"Entropy measures how much energy is dispersed in a particular process (at a specific temperature)."

I would assume that as far as thermodynamics are concerned "process" would refer to a chemical reaction and "at a specific temperature" would be problematic for light since I'm pretty sure it's unaffected by temperature.

Thanks for the link, FairFiend. I have a rapidly growing list of websites that I need to spend more time viewing.
I agree with you that, since the thermodynamic laws were given their first "formal" expression in the study of physical substances, they primarily apply to physical and chemical processes. I was thinking of entropy in more general terms (taking into account, for example, Einstein's principle of matter/energy equivalence) as a characteristic of the disorder of any physical system.

Hawkingfan · 02-04-2003, 02:25 PM

Quote:

Originally posted by Shadowy Man
Yes, you can get "interference" patterns with electrons. But this is not because they are canceling each other out.

If you perform a "two-slit" experiment with electrons what happens is that the wave nature of the electron interferes with the slits, not with other electrons.

I'm not arguing with this, but if I remember correctly from high school I thought the interference of the light waves and/or the electron wave nature was that the crest of one wave coincided with the trough of the other wave, therefore creating the fringes. Is that right, or am I totally off-base?

Shadowy Man · 02-04-2003, 03:19 PM

Quote:

Originally posted by Hawkingfan
I'm not arguing with this, but if I remember correctly from high school I thought the interference of the light waves and/or the electron wave nature was that the crest of one wave coincided with the trough of the other wave, therefore creating the fringes. Is that right, or am I totally off-base?

That is a misleading way of looking at it. If you send electrons through a two-slit experiment, but you send them in one at a time with a two week interval between electrons you will still get an "interference pattern" - assuming that the electrons all have the same energy.

So, in that case, can you say that the particles are interfering with each other, given that there is so much time in between events?

Many people are used to looking at light as purely a wave, with the intensity of the light being equal to the magnitude of the electric field vector. I, being an ultraviolet spectroscopist by training, am used to thinking of light as individual photons. An individual photon still manages to interact with a diffraction grating to get reflected at the correct angle for its wavelength even when we only get several hundred photons on the grating per second.

At some point you can't really say that the photons are interacting with each other. Go ask an X-ray astronomer - they typically have even lower count rates.

So, thinking of the troughs and the waves, etc. will give you the correct answer, but may not adequately reflect the "reality" of the situation, in my humble opinion.

Edited to add: This thinking of light as photons will get me in trouble if I ever switch to radio astronomy. Hehe... like that will ever happen.

02-03-2003, 12:51 PM	#12
Defiant Heretic Veteran Member Join Date: Jul 2002 Posts: 1,288	Just because something possesses the traits of two different things doesn't mean that it's self-contradictory. There�s a difference between �A and B� and �A and not A�. In case anyone reading this thread is a programmer, this shows what I'm talking about. Code: #include <stdio.h> int main(void) { int a,b;//1=true, 0=false for (a=0;a<=1;a++) { for (b=0;b<=1;b++) { if (a&&b) printf("\n\nTest1 Successful\na=%i\nb=%i",a,b); if (a&&!a) printf("\n\nTest2 Successful\na=%i\nb=%i",a,b); } } getchar(); return 0; }

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02-02-2003, 08:26 PM	#11
FairFiend Junior Member Join Date: Dec 2001 Location: East Lansing, MI Posts: 27	Thanks tk I don't know if I'd call them "mythical" concepts, but your explanation helped. Now I know why I didn't go into physics. For a mintue there I was about to become an agnostic.

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