# Max string frequency

1. Aug 6, 2007

### philiprdutton

If a string is a certain length then is there a max frequency? Is there a min frequency? These are beginner questions but answers would be appreciated. Also, if a string has zero frequency is it at rest? What would zero-frequency string mean in terms of energy?

2. Aug 6, 2007

### Claude Bile

There is no lower limit on the frequencies that can propagate along a string. Strings of a finite length possess a minimum resonance frequency, but this does not prevent lower frequencies from propagating along the length of a string. There is potentially an upper limit based on the material properties of the string - such as how much strain the string can take before breaking.

The zero frequency component is sometimes called the DC component, it is simply a constant displacement from equilibrium.

A string that has a frequency component at zero and only at zero will be at rest.

The energy is such a frequency component depends on how much work it took to displace the string from equilibrium in the first place.

Claude.

Last edited: Aug 6, 2007
3. Aug 6, 2007

### philiprdutton

movement

Thanks for your information! I shall have another question if you do not mind. Assume we have a large string about the size of our earth's moon. Assume it is not moving in the traditional 3 dimensions. Let's us say that the string is vibrating with some particular frequency. How can it it vibrate and not move in 3D space? Within string theory, might one consider vibrational frequencies as something that might trigger movement if the string is large enough to exist in 3D space?

4. Aug 6, 2007

### Danger

Philip, if your are referring to String Theory, it really has nothing to do with physical strings as you first asked about.
I would expand upon Claude's response only to point out that no vibration of any sort can exceed the speed of sound in the string, regardless of the structural integrity.

5. Aug 6, 2007

### philiprdutton

vibrations

Sure I understand that we are not talking about 3D strings. I was perhaps incorrectly using the word vibration. I really am talking about the 1D loops of string theory which undulate with some particular frequency. I thought that one particular version of string theory might suggest that something as "big" as a back hole could actually be a fundamental particle. In such talk, is a fundamental particle a string theory style string or is an elementary particle just something that happens to be composed of lots of string theory strings?

6. Aug 6, 2007

### Danger

That is far beyond my area of knowledge. Your best bet would be to contact the Cosmology or Theoretical Physics experts.

7. Aug 6, 2007

### philiprdutton

sorry

Darn. I thought I posted this in String theory discussion area. Sorry.

8. Aug 6, 2007

### Danger

No need to apologize. Just PM one of the Mentors, and s/he can move this to the appropriate forum.

9. Aug 7, 2007

### Staff: Mentor

Since the OP wants to discuss string theory, I've moved this to the "Beyond the Standard Model" forum.

10. Aug 7, 2007

### ZapperZ

Staff Emeritus
Actually, as far as I have read, the OP has no idea on what "String Theory" is. All the questions so far has been about ordinary vibrating strings in various dimensions from 1 to 3D. This is not THE String Theory. So this thread doesn't belong here.

Zz.

11. Aug 7, 2007

### philiprdutton

thanks for moving this

Thank you for moving this thread for me. I realized I placed it in the "CLASSICAL BORING PHYSICS" topic area by accident.

12. Aug 8, 2007

### ZapperZ

Staff Emeritus
I didn't move it. In fact, if you read my post, I am suggesting that it be moved out of the BTSM forum, since none of what your asking is beyond the ordinary vibration theory, which belongs in the classical physics forum.

Zz.

13. Aug 10, 2007

### philiprdutton

changed

Sorry, I will correct and restate the OP's question:

"In M theory, is a 'string' confined to a sub-range of frequencies which might be determined by which dimensions it happens to be residing in? What is the relationship between dimensions (their properties) and allowed frequency? Also, if a string/brane has zero frequency is this called rest? What would zero-frequency string mean in terms of energy?"