# Only wave, no particle

1. Jun 29, 2012

### lazer

Is there anything that can be considered just as a wave and not a particle or any wave that does not have particle?

2. Jun 29, 2012

### Nabeshin

3. Jun 29, 2012

### lazer

is it just wave.. it needs particle to exist

4. Jun 29, 2012

### Vorde

Not in the way I think you are meaning, no. Then again the closer you look the more the words 'wave' and 'particle' get blurry.

5. Jun 30, 2012

### Studiot

A wave in a continuous medium does not require the existence of particles to exist.

6. Jun 30, 2012

### K^2

A wave in continuous medium can still be quantized and considered a collection of particles, though. E.g. phonons. Any linear wave has particle properties, and any sufficiently small disturbance can be linearized. So the real answer is no, you can't really come up with anything that's just a wave.

7. Jun 30, 2012

### Studiot

Of course it can but I said it doesn't require discretisation which is the criterion.

8. Jul 1, 2012

### lazer

i have been thinking of it and i just felt this way: I think it is not possible to have anything like just wave because I do not think there can be any wave without energy. when there is energy there is mass. mass is a matter.. hence a particle.. may be not sure..

9. Jul 2, 2012

### Studiot

Depends on how you define a wave.

The wave equation doesn't require mass or even time for the time independent version.

It could be just squiggles on a piece of paper.

However if you want mass how about a vibrating string?

The entire medium forms the wave and the analysis does not require the separate existance of oscillating particles within the string.

10. Jul 2, 2012

### Staff: Mentor

You may be partially correct. All waves carry energy and have thus the system they are in has more mass than it would if the wave was not there, however mass does not make something a particle. If you take a jar of mayonnaise and heat it up it would have more energy and thus more mass but not more matter, so you would still make the same amount of delicious fried egg and mayo sandwiches as if it were cold. Is anyone else hungry now?

11. Jul 2, 2012

### Studiot

Careful, standing waves do not carry energy although the possess energy. Their energy stays in one place.

12. Jul 2, 2012

### Staff: Mentor

That is how I am using the word "carry". To have energy, to possess it. Is this incorrect?

13. Jul 2, 2012

### Studiot

So long as it is clear to all I don't think it matters.

Travelling waves transport energy from the source to the end of the wave (ie the wave front). So until the energy is dissipated it is always travelling outwards away from the source and must be replenished by the source for the wave to keep going.

Standing waves do not transport energy. So once established the wave does not need further input of energy (dissipation apart).

Waves as squiggly lines on a piece of paper need no energy at any stage.

14. Jul 2, 2012

### Redbelly98

Staff Emeritus
Well, what about the discrete molecules of water that comprise such a wave?

But -- can you give an example of a continuous medium that actually exists?

15. Jul 2, 2012

### Naty1

a distinction without meaning.

If I stand still with a bucket of water, am I "carrying" it???

16. Jul 2, 2012

### Naty1

nope.
In general, any matter [such as a particle] has an associated wave [the deBroglie wave] and a 'particle' can be considered a quanta of a wave. So for example, a photon is a quanta [particle] of light [which is an electromagnetic wave] .

17. Jul 2, 2012

### Studiot

No more than I can give an example of a perfect straight line or a frictionless surface etc etc that actually exists.

However any theory must be valid for such thought constructs.

I did not want to extend the discussion to higher level but since you introduce it,

The wonderful thing about nature is not that perfect continuous media cannot be found, but that an equation only proved in continuous mathematics for continuous media can be applied at all to granular systems.

That is what notion is what should be pursued.

18. Jul 2, 2012

### Redbelly98

Staff Emeritus
Well, by that logic the answer to the OP is pretty simple:
And we could say "Yes. Light can be considered to be strictly a wave, as long as there are a large enough number of photons present so that the classical notion of light as a continuous wave is a reasonable approximation."

But I thought we were doing away with any such approximations in this discussion, at least that is my interpretation of the OP's question.

By the way, I completely agree with this sentiment:
I just don't think it is relevant to what the OP was asking.

19. Jul 2, 2012

### Studiot

Already answered. There is a difference between stating that a wave requires discrete particles to operate and that a bunch of particles can jump up and down to form a wave.

20. Jul 2, 2012

### Nabeshin

Of course, I was just giving an example of a classical wave which has no corresponding quantized 'particle', which is what I took the OP to be meaning. I'm still not sure precisely what he is asking, though.