empty space has an energy density, true or false?

Question

Sorry Rahul, the others seemed to understand it!!

Answer 1

Like these Q's!!

From a quantum viewpoint, true

Answer 2

Hi yodaisneverwrong

I'm not sure what your physics background is, but here's some extra detail for you anyway:

The zero point energy mentioned above is basically the difference between the classical and quantum expectation values for the vacuum. The key differentiator is the uncertainty in time. You may be familiar with Heisenberg's Uncertainty Principle (HUP) in it's most common form: del(x) * del(p) =/> h-bar/2. the operators for position (x) and momentum (p) are one set of what is called non-commuting operators. The HUP limits the precision with which you can simultaneously know both operators: the more precisely you measure momentum the less precision you can measure in position and vice versa.

Anyway, there are a number of other non-commuting operator pairs and you can construct HUP relations for each. One such pair is energy (E) and time(t). The HUP constrains your measurements in energy, and this translates into an uncertainty about a zero or ground state. The uncertainty is (in a manner of speaking) the zero point energy.

Now before you get exceited and started running around trying to extract and use this "vast reservoir of free energy" (like the rabid "free lunch" zpe fanatics), a couple of points about this zpe:
* first - the scale of the fluctuations associated with uncertainty is set by the appearance of Planck's constant (h) in the relation: h is on the order of 10^-34 J.s (0.000 000 000 000 000 000 000 000 000 000 000 6 Joule-seconds). That's *very* small.
* second - vacuum fluctuations tend to average out over any reasonable time scale (again due to the scaling factor h)


Hope this helps!
The Chicken

Answer 3

True. Enjoy Wikipedia!

"In Physics, "Vacuum energy" or "zero-point energy" is the volumetric energy density of empty space. More recent developments have expounded on the concept of energy in empty space.

Modern physics is commonly classified into two fundamental theories: quantum field theory and general relativity. Quantum field theory takes quantum mechanics and special relativity into account, and it's a theory of all the forces and particles except gravity. General relativity is a theory of gravity, but it is incompatible with quantum mechanics. Currently these two theories have not yet been reconciled into one unified description, though research into quantum gravity" seeks to bridge this divide.

In general relativity, the cosmological constant is proportional to the energy density of empty space, and can be measured by the curvature of space. It is subsequently related to the age of the universe, as energy expands outwards with time its density changes.

Quantum field theory considers the vacuum ground state not to be completely empty, but to consist of a seething mass of virtual particles and fields. These fields are quantified as probabilities - that is, the likelihood of manifestation based on conditions. Since these fields do not have a permanent existence , they are called vacuum fluctuations. In the Casimir effect, two metal plates can cause a change in the vacuum energy density between them which generates a measurable force.

Some believe that vacuum energy might be the "dark energy" (also called quintessence) associated with the cosmological constant in General relativity, thought to be similar to a negative force of gravity (see antigravity). Observations that the expanding Universe appears to be accelerating seem to support the Cosmic inflation theory — first proposed by Alan Guth (1981) — in which the nascent Universe passed through a phase of exponential expansion driven by a negative vacuum energy density (positive vacuum pressure)."

Answer 4

If by 'empty space' you mean space which contains no matter, then yes, it can contain energy in the form of electromagnetic fields.

Answer 5

Empty space ? are you talking about Vacuum as in space / universe or is it something like a space on earth without any physical things but air remains, like an empty room ? please make your question clear, if you are looking for an appropriate answer :-)

Answer 6

True

Answer 7

true... but never been discovered to produce energy from it

Answer 8

i think true