# Help Me with Vacuum Energies quote

1. May 18, 2004

The following is from a book i'm reading:

(With regard to uncertainty and vacuums)

can someone explain whats going on there.

2. May 23, 2004

### Blackforest

To fbsthreads and to anyone on this forum: Sorry I cannot help; and I tell the same question than you: what is really happening in vacuum? I think if someone can explain it with precision: he is the next "Nobel" in physics. Energy in vacuum is actually an enigma. Or is there some one with a super answer and a solution? Thanks for more informations too.

3. May 23, 2004

### sol2

With all the math involved in superstringtheory one might think it will eventually list the geometrically basis to our reality Who knows?

Or it is one of those things, where we will keep developing the math until we run out of room. Pure speculation. We know einstein got to where he did by following some basic geometerically defined rules.

Does it not have to be this way in understanding the dynamics of the universe?

So when you run out of tools for explaining, what do you think these mathematicians do? They create a new math I say......Reinmann couldn't have seen without the help of gauss's vision?

Or smolin, in developing a "synthesis" that arose out of pure logic from three roads?

Last edited: May 23, 2004
4. May 23, 2004

Staff Emeritus

The unseen player in this description is the uncertainty principle. The UP says that the product of the uncertainty in the energy of a particle times the uncertainty of its time (i.e., its lifetime) is greater than or equal to a certain small constant. Thus if the uncertainty of one of them is small, the uncertainty of the other is large.

Now to be observable, a particle has to be "on the mass shell" which is code for the equation* $$p^2 = e^2 - m^2$$. In a virtual particle, the equation is not satisfied because the energy and momentum are small in accordance with the uncertainty principle.

So you can imagine a particle that comes into being from the vacuum, has a lifetime too short and an energy and momentum too small to be observed, and dies. This is a virtual particle. energy and momentum are conserved, "up to the uncertainty".

* In units with c = 1.