String theory

[Little Bang]

So there is a standard model explanation for why the collision between two waveforms created an electron and positron at the Stanford linear accelerator? It seems curious to me that one of the forces mediated by a standard model particle is turned into a particle.

[Jay-qu]

Im not saying the standard model is correct - it is most certainly not complete or able to explain everything. What I am saying however is that I think there is a flaw in your reasoning and I dont think we can resolve the current 'whys' until we take a few more big steps in the right direction.

[Erasmus00]

So there is a standard model explanation for why the collision between two waveforms created an electron and positron at the Stanford linear accelerator?

 

Yes, there is. In the standard model vacuum, electron-positron pairs are always appearing and disappearing. The photons at SLAC don't directly interact, but rather interact with the electron-positron pairs giving them energy, ripping them apart.

 

It seems curious to me that one of the forces mediated by a standard model particle is turned into a particle.

 

You seem to think the photon is really a wave, not a particle. How then do you explain all the evidence for the particle nature of photons?

-Will

[Qfwfq]

Perhaps LB you are thinking of boson vs. fermion, but the basics of field theory work both ways.

 

A particle is really a wave, a wave is really a particle. If charged fermions can interact via photons, then photons can interact via charged fermion-antifermion pairs. The graph can be viewed as two Compton graphs with their fermion lines joined to make one loop.

[steve 9]

Why is the number of dimensions in string theory so specific? Does it not seem like scientists are 'making up' the theory of extra dimensions because they cannot explain why the force of gravity is so weak compared to the other fundamental forces. The idea of miniscule undetectable universes present in our own seems to have derived from nowhere.

 

 

 

Go ahead and try to find any scientific reference that states spatial dimensions are physical things. String theory is based on extra dimensions. These string guys can not nor have not defined a spatial dimension as a physical thing. It is all fantasy and mathmatical models, not reality.

[steve 9]

Hi Kalexia, where have you been reading about string theory? it seems you have heard some little facts about it without understanding the reason behind them.

 

String Theory works by representing all the fundamental particles with strings instead of being point like. There are many versions of String Theory, some have closed stings - loops, some open, and some include more exotic forms such as branes. Im not sure if its always the case but these strings are only 2-dimensional, in order for all the particles to be described by the theory they are proposed to 'vibrate'. Different vibrational patterns give rise to different properties of the particles. It turns out that string theory requires 10 dimensions (bosonic actually needs 26..) to have solutions that result in flat spacetime like we observe.

 

 

Show me a scientific reference that states that spatial dimensions are physical things.

[steve 9]

Hi. I do know these facts about string theory but I can't get my head around the compactification of several of the dimensions to make our currently existing four and that there may exist microscopic universes with more dimensions within our own.

 

 

Go and define the term dimension. Then you will see that string theory is not based on any obsevered physical data. It is all pure math, no reality.

[Essay]

Go and define the term dimension. Then you will see that string theory is not based on any obsevered physical data. It is all pure math, no reality.

 

I don't want to get caught up in Lie algebra and Dirac operators, Finsler sprays, or Hawking "nuts & bolts," but....

 

Who says dimensions must be spatial. I'd argue that spacetime is simply an artifact of the other dimensions.

The other dimensions inform or create this reality we perceive. (imho)

 

I find it helpful to specifically avoid thinking of other dimensions in spatial terms. For instance:

electro/magnetism;

enthalpy/entropy; or even,

synchrony/discord;

intention/inertia;

empathy/apathy;

joy/despair.

 

I suspect if you label your dimensions correctly, you'll create a universe with a personal G0d; but that has nothing to do with String Theory.

 

There is no space, time, matter, or energy; it's all just dimensionality.

Doesn't E8 + SU3 = 11 dimensions?

:):hihi:

[kalexia]

Go and define the term dimension. Then you will see that string theory is not based on any obsevered physical data. It is all pure math, no reality.

 

I realise that string theory is not proven and is only speculation. However, all theories must originate somewhere down the line from known facts and it was these facts that I was referring to, ie: why 11 (or 26) dimensions, why not 15, 22, 30 etc?

[Qfwfq]

...string theory is not based on any obsevered physical data.

Actually it is consistent with all observation.

 

There is no known experimental way of contradicting it that would not contradict something else too. It isn't based on any physical hypothesis further to those of what it is meant to "explain", IMV it isn't a theory but a formalism.

[steve 9]

I realise that string theory is not proven and is only speculation. However, all theories must originate somewhere down the line from known facts and it was these facts that I was referring to, ie: why 11 (or 26) dimensions, why not 15, 22, 30 etc?

 

 

What is known about dimensions? Have you seen any evidence that dimensions are things that are physical and can be looked for?

[steve 9]

Actually it is consistent with all observation.

 

There is no known experimental way of contradicting it that would not contradict something else too. It isn't based on any physical hypothesis further to those of what it is meant to "explain", IMV it isn't a theory but a formalism.

 

 

What observed data? What scientific reference or observation states that dimensions are physical things that can be looked for? What observations are you referring to?

[Little Bang]

Suppose you could be an observer speeding along beside a photon. The photon is headed toward the center of a black hole. As the photon approaches the black hole it's wavelength becomes shorter and shorter until it hits the center at which point it's wavelength is 0 and it's frequency is infinite " and " there is no time. That is a dimension, just like the one from which our universe was born. Within the next two to four weeks I hope to give you the nuts and bolts of gravity, of charge, and mass.

[Moontanman]

Show me a scientific reference that states that spatial dimensions are physical things.

 

I think that brane theory depends on multiple spatial dimensions being real. But it also implies that exploring or proving these spatial dimensions would take more energy than we can cause to come together in a small space such as an accelerator. But it does imply that such a proof may be possible at some point.

[jedaisoul]

Go and define the term dimension. Then you will see that string theory is not based on any obsevered physical data. It is all pure math, no reality.

I don't want to get caught up in Lie algebra and Dirac operators, Finsler sprays, or Hawking "nuts & bolts," but... Who says dimensions must be spatial. I'd argue that spacetime is simply an artifact of the other dimensions. The other dimensions inform or create this reality we perceive. (imho)

I'm with steve 9 on this. What we observe are three spatial dimensions and one time "dimension". That is reality. Any theory about 11 or so dimensions, is just that, theory. It is not supported by any evidence. All it does is predict the value of gravity that we see in practice. That does not make it correct, it just means that it conforms to the known value of gravity. But it does not conform to the known number of dimensions. So you can either say:

a) The known number of dimensions is an illusion.

:hihi: String theory fails to correspond to reality in this respect.

 

I know which answer I chose!

 

Note: I put the time dimension in quotes because it is not a dimension in the same sense as the spatial ones. You cannot move freely in the time dimension in the same sense as you can the spatial ones. So you really should not use the same word for it in the same context. But that is the word that is commonly used, so I have to use it.

 

Oh, and if you are using the word "dimension" to mean something other than what we observe, you are simply "muddying the water" by changing the meaning of a word to fit the theory.

[HydrogenBond]

I did this analogy before but it is worth repeating. If we start with the three primary colors, one can make any color on one graph if we make a 3-D plot using these three dimensions.

 

If we work under the assumption of 2-D, therefore only allowing two colors per plot, we will need three plots for the three combinations of 2 colors. Since we can't make white or neutral grays out of just two primary colors we also need a plot for that, where we sort of combine the other plots. Then there are the yellow-grays, red-grays, blue-grays. each requiring a plot.

 

In the second scenario we could call each plot a new dimension. But it is only needed because of the original assumption of 2-colors per plot. There may be certain advantages, such as simplicity, to go this route. If nobody thought to plot all three colors on one graph, then it may appear like all these extra plots or dimensions are needed, since they are under these particular circumstances. But in the same token, the additional plots may give us a better feel for building up three color blends. Eventually, someone will get the idea of 3 color compaction, lowering dimensions.

[jedaisoul]

I did this analogy before but it is worth repeating. If we start with the three primary colors, one can make any color on one graph if we make a 3-D plot using these three dimensions.

True, but see below...

If we work under the assumption of 2-D, therefore only allowing two colors per plot, we will need three plots for the three combinations of 2 colors. Since we can't make white or neutral grays out of just two primary colors we also need a plot for that, where we sort of combine the other plots. Then there are the yellow-grays, red-grays, blue-grays. each requiring a plot.

False. What you are describing is a set of "slices" through the 3D volume, not the totality of the volume.

 

To fully desribe the 3D set you would need more than a "yellow-gray", a "magenta-grey" and a "cyan-grey" plot (not "red-grey" and "blue-grey"). In fact you would need 256 different plots. The good news is that, with a full set of 256 plots, the three original two color plots would be superfluous!

 

However, that only describes the color set determinable by the human eye. It is not the full range of colours possible. Why? Because the rainbow alone contains a (theoretically) infinite number of prime colors. The three prime colors used as a basis of the 3D set rely on the ability to fool the mind into believing that it is seeing colors that are not actually there. This works because it mimicks the way that the eye detects color. So it is an illusion.

 

In the second scenario we could call each plot a new dimension. But it is only needed because of the original assumption of 2-colors per plot. There may be certain advantages, such as simplicity, to go this route. If nobody thought to plot all three colors on one graph, then it may appear like all these extra plots or dimensions are needed, since they are under these particular circumstances. But in the same token, the additional plots may give us a better feel for building up three color blends. Eventually, someone will get the idea of 3 color compaction, lowering dimensions.

I know it's only intended as an analogy, but even as an analogy it does not work. Even if we ignore the technical issues mentioned above. The point is, we already know that space is three dimensional. No one is forcing it into two dimensions. So it does not describe an analogous situation.