String Theory, M-Theory, whatever

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Discussion Overview

The discussion revolves around the nature of strings in string theory, particularly their mass, vibration, and implications for particles such as photons and dark matter. Participants explore theoretical concepts related to the properties of strings and their role in the universe, including energy-mass equivalence and the characteristics of dark matter.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that strings have mass, which depends on their vibrational modes, while others question the implications of this mass for particles like photons.
  • There is a suggestion that the vibrational energy of strings could be equivalent to mass, raising questions about whether strings themselves "have mass" or if it's a reflection of their energy.
  • One participant argues that dark matter could be made of strings, but another counters that this is not obvious and highlights the unique properties of dark matter.
  • Quantum jitters and their relationship with string vibration energy are discussed, with some suggesting that this could lead to massless particles like gravitons.
  • The relationship between energy and mass is noted, with references to Einstein's formulation and the implications for particles in string theory.
  • Participants mention the incompleteness of string theory and its experimental challenges, while also suggesting that insights into dark matter and dark energy could reshape our understanding of matter.

Areas of Agreement / Disagreement

Participants express a range of views on the nature of strings and their properties, with no consensus reached on whether strings have mass or how they relate to dark matter and energy. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Some claims depend on specific interpretations of string theory and its implications, which are not universally accepted. The discussion includes speculative ideas about the nature of mass and energy in relation to string vibrations, reflecting the complexity and ongoing debates within the field.

Who May Find This Useful

This discussion may be of interest to those exploring theoretical physics, particularly string theory, and its implications for particle physics and cosmology.

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Does these strings have mass?

So, everything's made of these strings. Obviously, dark matter would also be made of strings, vibrating to give them certain properties? What makes them vibrate?

Are photons made of strings? If strings have mass, then the mass can't just vanish, if photons are strings..

Could strings vibrate a certain way to be energy? I kow there's a connection between energy and mass, but does energy have mass?

I know, lousy questions. It's just that I'm wondering.
 
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Yes, strings have mass, but the amount depends on the way the string is vibrating. This also answers you second question: the type of vibrations determines what type of particle the string corresponds to. In turn, there is a vibriational mode which corresponds to the photon. This vibrational mode does not carry any mass - just like the photon.
 
xepma said:
Yes, strings have mass, but the amount depends on the way the string is vibrating. This also answers you second question: the type of vibrations determines what type of particle the string corresponds to. In turn, there is a vibriational mode which corresponds to the photon. This vibrational mode does not carry any mass - just like the photon.

This is interesting, can you maybe elaborate a little on the way in which the vibrational mode determines mass?

Also (if this question makes sense) in these cases does the string actually "have mass"? Or would it be more correct to say that the vibrational energy of the vibrating string is equivalent to a certain amount of mass?
 
So, everything's made of these strings. Obviously, dark matter would also be made of strings, vibrating to give them certain properties? What makes them vibrate?

It's possible, but NOT obvious. Not likely in my layman's opiion. Dark matter appears unique in that it's the only matter that does not reflect light...and nobody knows what it is. Dark energy consitutes about 70% of the universe, dark mass about 26% and all common matter (neutrons,protons,electons,etc) only 4%...we know little about 96% of the universe! A guess is that when we figure out dark matter and dark energy we'll have new insights into what constitutes "common" matter.

Quantum jitters (energy) are reflected in overall of string vibration energy...yet quantum jitters of strings alone reflect negative energy!...for the graviton, the energy cancellation between quantum jitters and string vibration energy is perfect...hence a zero mass gravitational like particle emerges.


Are photons made of strings? If strings have mass, then the mass can't just vanish, if photons are strings..

Some strings appear as gravitons, other as photons. Some are bosons (matter particles) some fermions (force particles)...but string theory is incomplete and largely unproven experimentally while it has offered significant insights...in a sense mass CAN vanish becauseit's a reflection of energy and quantum energy can offset string vibrational energy. In field theories, photons are waves (fields); in quantum theory photons are quanta (particles);in string theory, they are vibrating strings...one dimensional bits of energy. Take your pick!

Could strings vibrate a certain way to be energy? I kow there's a connection between energy and mass, but does energy have mass?

yes, energy is equivalent to mass...as formulated by Einstein...His stress energy tensor reflects gravity resulting from mass,energy,stress...in string theory, gravitons and photons, for example, have energy but no mass in accordance with the standard model of particle physics. Higher modes of energy vibrations resuls in higher mass particles.

You can try Brian Greene's books (Fabric of the Cosmos, The Elegant Universe) or Lee Smolin's The Trouble with Physics for good discussions of all this...available in paperback...
 
Or would it be more correct to say that the vibrational energy of the vibrating string is equivalent to a certain amount of mass?

I like that better.
 
Those interested can find a discussion of string theory in Wikipedia at...
http://en.wikipedia.org/wiki/String_theory

It jumps right into rather advanced concepts at points, typical of Wikipedia, but you can get a basic idea of some of the ideas used...Greene and Smolin have clearer explanations in my opinion along with interesting insights...

Also I posted a brief discussion thread about how space time might emerge from string theory here in physics forums:
https://www.physicsforums.com/showthread.php?t=297908
 

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