String theory

[morgsboi]

Okay, I have a basic understanding of string theory but not lots so:

 

Please could someone explain it.

What are the strings made of?

And if what makes up and element are millions of tiny strings vibrating in different frequencies, then why are there not trillions of different elements or I (imaginary number) due to the amount of possible combinations of frequencies together as each string is around 10^-35 meters?

[Realitycheck]

Another question would be how many strings exist in a vacuum? In deep space, where you have around 10 atoms per cubic meter, is it still considered to have a separate string for each Planck length?

[morgsboi]

Another question would be how many strings exist in a vacuum? In deep space, where you have around 10 atoms per cubic meter, is it still considered to have a separate string for each Planck length?

 

Good question, but I don't know the answer. But it still doesn't solve my questions.

[Mystery111]

Another question would be how many strings exist in a vacuum? In deep space, where you have around 10 atoms per cubic meter, is it still considered to have a separate string for each Planck length?

 

I will get to the OP soon. To answer your question, there maybe up to 10^80 strings in a single vacuum. This is the least amount of strings required.

 

Okay, I have a basic understanding of string theory but not lots so:

 

Please could someone explain it.

What are the strings made of?

And if what makes up and element are millions of tiny strings vibrating in different frequencies, then why are there not trillions of different elements or I (imaginary number) due to the amount of possible combinations of frequencies together as each string is around 10^-35 meters?

 

 

 

Strings are made of energy. They are vibrating strings of energy, with that energy conneted to the frequency of each vibration.

 

We have the elements we have due to what is called the Pauli Exclusion Principle. This Principle is enough and all that is required to explain why we have the elements we have.

[morgsboi]

I will get to the OP soon. To answer your question, there maybe up to 10^80 strings in a single vacuum. This is the least amount of strings required.

 

 

 

 

 

Strings are made of energy. They are vibrating strings of energy, with that energy conneted to the frequency of each vibration.

 

We have the elements we have due to what is called the Pauli Exclusion Principle. This Principle is enough and all that is required to explain why we have the elements we have.

 

Okay, so I understand that they come from energy so would that be from kinetic or friction?

And please could you give me very basic version of the principal because quantum mechanics isn't really my thing.

Thanks

[Mystery111]

Okay, so I understand that they come from energy so would that be from kinetic or friction?

And please could you give me very basic version of the principal because quantum mechanics isn't really my thing.

Thanks

 

Kinetic.

 

you want a basic version of what sir? String Theory?

[morgsboi]

Kinetic.

 

you want a basic version of what sir? String Theory?

Only for somewhere to start.

[SinkingBiscuits]

Okay, I have a basic understanding of string theory but not lots so:

 

Please could someone explain it.

What are the strings made of?

And if what makes up and element are millions of tiny strings vibrating in different frequencies, then why are there not trillions of different elements or I (imaginary number) due to the amount of possible combinations of frequencies together as each string is around 10^-35 meters?

 

Although Mystery111 has already given you a good answer, I thought it may be of benefit to you if I went into some further explanation-

As has been said, the reason a select amount of elements exists regardless of the potential combinations string theory allows is because of the Pauli exclusion principle. This is the principle that states that particles of like charges will repel each other, ie. protons will repel protons, electrons will repel electrons. The strong nuclear force allows atoms to exist despite the close proximity of protons within the nucleus, however, there comes a point where there are enough protons in the nucleus of an atom for the 'outer' protons to be far enough away from each other for the Pauli exclusion principle to come into play, thus the atom is unstable. So in the case of naturally occurring elements, 92 is the max number of protons that can successfully exist within the nucleus (Uranium).

 

As for strings in a vacuum (given that we are referring to a theoretical 'complete' vacuum), strings would still exist, despite the vacuum being devoid of matter, due to the presence of vacuum energy. As for the quantity, I have no clue.

 

I hope this has been helpful.

[questionposter]

Okay, I have a basic understanding of string theory but not lots so:

 

Please could someone explain it.

What are the strings made of?

And if what makes up and element are millions of tiny strings vibrating in different frequencies, then why are there not trillions of different elements or I (imaginary number) due to the amount of possible combinations of frequencies together as each string is around 10^-35 meters?

 

String are suppose to be 1 dimensional oscillating strands of energy. As far as scientists have come up with, there are only 5 types of them, and some can extend to different sizes, even to the size of the universe. The reason there aren't millions of elements is because of how sub-atomic particles add up as you increase the amount of them in a specific area. If you have too big of a nucleus, the strong force can't hold it together, it just takes too much energy to do so and the nuclei are too big.

[questionposter]

Okay, I have a basic understanding of string theory but not lots so:

 

Please could someone explain it.

What are the strings made of?

And if what makes up and element are millions of tiny strings vibrating in different frequencies, then why are there not trillions of different elements or I (imaginary number) due to the amount of possible combinations of frequencies together as each string is around 10^-35 meters?

 

String are suppose to be 1 dimensional oscillating strands of energy. As far as scientists have come up with, there are only 5 types of them, and some can extend to different sizes, even to the size of the universe. The reason there aren't millions of elements is because of how sub-atomic particles add up as you increase the amount of them in a specific area. If you have too big of a nucleus, the strong force can't hold it together, it just takes too much energy to do so and the nuclei are too big.

[MigL]

Trying to keep things as simple as possible...

 

A quantum theory of gravity is not re-normalisable because the force carrier particles of the quantum field as well as the elementary particles they act on are considered to be point particles. The infinities that arise in the calculations cannot be re-normalised away like in QCD and QED.

So someone ( cannot remember who at the moment ) decided to use a pre-existing theory ( being used for something else ), and consider all elementary particles such as electrons and quarks, and bosons like photons, gluons and gravitons, to be composed of open or closed loops of vibrating space/time at Planck scale size . Different harmonics of the vibrations giving rise to different masses, spins and charges of particles.

The masses that string theories predict for particles are not very accurate, but all ( there are many ) predict a spin 2 boson which turns out to be the graviton. That is one of the biggest attractions of string theory, the fact that it predicts the graviton and so points to a quantum field theory of gravity.

There have been several iterations of string theory, the latest being Witten's M-theory, where all force carrying bosons are open ended and the ends anchored to branes except for gravity, where the graviton is a close loop string and free to pass between branes ( which leads to some complicated results for gravity and its inverse square law ).

String theory has however, made no veryfiable predictions and is at the moment, just a very elegant mathematical theory in search of a universe to describe.

 

As for the vacuum containing strings, what Mystery111 may have been referring to are virtual particles which saturate space, so yes they would be present in a vacuum, but they only make up point particles. That being said our understanding of vacuum energy leaves a lot to be desired as our estimates are 10^100 times higher than expected.

 

As for the elements, others have already explaned. I would only add that only certain numbers of nucleons lead to stable configurations,I'm not sure if QCD explains this as I haven't read up on it since my nuclear physics class in the late 70s.

Edited November 12, 2011 by MigL

[Mystery111]

Although Mystery111 has already given you a good answer, I thought it may be of benefit to you if I went into some further explanation-

As has been said, the reason a select amount of elements exists regardless of the potential combinations string theory allows is because of the Pauli exclusion principle. This is the principle that states that particles of like charges will repel each other, ie. protons will repel protons, electrons will repel electrons. The strong nuclear force allows atoms to exist despite the close proximity of protons within the nucleus, however, there comes a point where there are enough protons in the nucleus of an atom for the 'outer' protons to be far enough away from each other for the Pauli exclusion principle to come into play, thus the atom is unstable. So in the case of naturally occurring elements, 92 is the max number of protons that can successfully exist within the nucleus (Uranium).

 

As for strings in a vacuum (given that we are referring to a theoretical 'complete' vacuum), strings would still exist, despite the vacuum being devoid of matter, due to the presence of vacuum energy. As for the quantity, I have no clue.

 

I hope this has been helpful.

 

 

I don't believe that the Pauli Exclusion Principle really states that like charge particles repel. That is a matter of electrodynamics.

 

Pauli's Exclusion Principle really says that spin is cancelled out. If a particle has a spin down for instance when interacting with another particle, then the other particle will exhibit a spin up. In effect, what I think you where saying from the nature of your post, is that due to spin coherence there is no one energy level in an atom which can be occupied by two fermions sharing the same spin directionality.

 

Trying to keep things as simple as possible...

 

A quantum theory of gravity is not re-normalisable because the force carrier particles of the quantum field as well as the elementary particles they act on are considered to be point particles. The infinities that arise in the calculations cannot be re-normalised away like in QCD and QED.

So someone ( cannot remember who at the moment ) decided to use a pre-existing theory ( being used for something else ), and consider all elementary particles such as electrons and quarks, and bosons like photons, gluons and gravitons, to be composed of open or closed loops of vibrating space/time at Planck scale size . Different harmonics of the vibrations giving rise to different masses, spins and charges of particles.

The masses that string theories predict for particles are not very accurate, but all ( there are many ) predict a spin 2 boson which turns out to be the graviton. That is one of the biggest attractions of string theory, the fact that it predicts the graviton and so points to a quantum field theory of gravity.

There have been several iterations of string theory, the latest being Witten's M-theory, where all force carrying bosons are open ended and the ends anchored to branes except for gravity, where the graviton is a close loop string and free to pass between branes ( which leads to some complicated results for gravity and its inverse square law ).

String theory has however, made no veryfiable predictions and is at the moment, just a very elegant mathematical theory in search of a universe to describe.

 

As for the vacuum containing strings, what Mystery111 may have been referring to are virtual particles which saturate space, so yes they would be present in a vacuum, but they only make up point particles. That being said our understanding of vacuum energy leaves a lot to be desired as our estimates are 10^100 times higher than expected.

 

As for the elements, others have already explaned. I would only add that only certain numbers of nucleons lead to stable configurations,I'm not sure if QCD explains this as I haven't read up on it since my nuclear physics class in the late 70s.

 

 

My calculation only works for one dimension. The true calculation should be [math]3 \cdot 10^{80}[/math] particles in the observable universe, 3 to account for the three dimensions of space. This aint virtual particle stuff I am talking about.

[MigL]

Ah, so 3x10^80 is a guesstimate for the total number of particles in the universe. But what about photons ( and other bosons ) which saturate all space and make up the CMB, are they included in this rough calculation?

And yes virtual particles are a manifestation of vacuum energy.

[Mystery111]

Ah, so 3x10^80 is a guesstimate for the total number of particles in the universe. But what about photons ( and other bosons ) which saturate all space and make up the CMB, are they included in this rough calculation?

And yes virtual particles are a manifestation of vacuum energy.

 

Rough as it is, you can take my calculation as something at, either more or less, the value I gave. All space is saturated with energy. What this calculates is the observable mass. The stuff we see.

[guenter]

Hi,

 

to my (very basic) knowledge, string theory does'nt predict the masses of the elementary particles.

However are there any hints about the relation of masses? For example the masses of electron/proton or constituent quark mass / current quark mass? And further, does the string theory predict, which particles have rest mass and which not? In this context, how about the neutrino?

 

regards, guenter

[MigL]

Without getting into too much detail ( because I'd be in over my head ), the string vibration is just like any oscillation, the requency and amplitude determine the energy and the energy is related to the mass. The problem is that extremely small mass particles like neutrinos or electrons even, are predicted to have zero mass by the theory. And while this may be to a good approximation, it is definitely not accurate. The same is true of massive particles, the masses are only approximate or rounded off. Anyone having a more detailed understanding of string theory mass predictions is welcome to correct me or add to my simple explanation.

 

I first read about this problem with masses in a popularization ( Brian Green, not Elegant Universe, but his subsequent ), so I don't have a good understanding of it myself.

[guenter]

Ok, so the string theory does'nt say much about masses. Then I am not optimistic that it sheds light on my next question:

 

The standard model can't explain why the charge of the elektron equals that of the proton (with the exception of the sign). Why is the H-Atom neutral? The Gut's are dealing with that. But also a theory which aims to be a ToE, like the string theory, should answer such questions, right?

 

But it might well be, that I have a wrong imagination of what the string theory should be able to predict. The predictions of General Relativity include the predictions of Newtonian gravity. With the right simplifications one can arrive at Newton starting from GR. From this my reasoning is: Shouldn't a ToE predict the predictions of the sub theories, QM, the standard model, the GUT's?