Trying to understand branes

[rrw4rusty]

Hi!

 

Are M-Theory’s ‘other’ branes (that is, not ours) thought to physically exist 'elsewhere'… that is, in another universe somehow ‘next’ to ours… i.e. not mingled within our physical space.

 

Or, do these 'strings on other branes' purport to exist within our space – that is, intermixed with the strings on our brane?

 

Or... all of the above.

 

It would seem that this would be… one way or the other. Or, is the answer is neither… and is it one of those ‘things’ which is expressed in the mathematics but, is beyond what mortal man can imagine, envision or understand, LOL. It can be that way if you don't know the math.

 

Thanks any help!

Rusty

[ajb]

Or, do these 'strings on other branes' purport to exist within our space – that is, intermixed with the strings on our brane?

 

The M2 and M5 brane of M-theory are not Dp-branes. Strings do not end on them. There can also be p-branes in string theories that are not necessarily Dp-branes. D = Dirichlet and refers to the boundary conditions of the open strings.

 

If our word is a D3-brane then it is quite possible that other D3-branes are present in the bulk, as well as other p-branes and Dp-branes.

 

 

I remember Warren Perkins talking about a calculation he made a few year ago about branes colliding. He stated that the probability of a collision does not decrease with time. (Given his initial conditions etc...)

 

This could be worrying. It is possible that the collision of branes is what started the big bang. This is called "ekpyrotic colliding brane cosmology". One would hope that this happens once and then the chances of it happening again die quickly. So, watch out for branes that come to close!

[rrw4rusty]

The M2 and M5 brane of M-theory are not Dp-branes. Strings do not end on them. There can also be p-branes in string theories that are not necessarily Dp-branes. D = Dirichlet and refers to the boundary conditions of the open strings.

 

If our word is a D3-brane then it is quite possible that other D3-branes are present in the bulk, as well as other p-branes and Dp-branes.

 

 

I remember Warren Perkins talking about a calculation he made a few year ago about branes colliding. He stated that the probability of a collision does not decrease with time. (Given his initial conditions etc...)

 

This could be worrying. It is possible that the collision of branes is what started the big bang. This is called "ekpyrotic colliding brane cosmology". One would hope that this happens once and then the chances of it happening again die quickly. So, watch out for branes that come to close!

 

Hello again ajb!

 

Thank you for replying. I understand and concur with your last 2 paragraphs. The rest flies over my head a bit. I was hoping to avoid getting into the different types of branes as Greene does in his Nova The Elegant Universe videos. The audience of my project is the same as that series. Ergo, you look at what all brane types can do, select the interaction you wish to discuss and remove the brane's type specification.

 

It looks like you are saying that, yes strings on other branes 'could' exist amount the strings on our brane (the bulk?). Whither this would be 'common' or 'rare' would be nice to know. When asked where these parallel universes were, Kaku said 'right in your living room'. This led me to believe that some strings on some type of branes, within some context, existed within and around each other.

 

As for 'colliding': assuming that Kaku's statement was true then I had to assume that the definition of colliding could be something other then 'touching' or, there could be a natural repulsion holding them apart so that even mixed brane strings would see like those wavy vertical sheets that are shown which I assumed was a logical view (and not a physical view).

 

Thanks so much for your help!

 

Rusty