How does one describe the energy of space to the public?

solarblast

See Subject. How does one simply explain that space is permeated by energy and what it represents? Feynman mentions that we really do not know what it is, but yet we do know how the calculate it. How do we know that it's there (in space)?

phyzguy

What do you mean by the "energy of space" Do we really have a self-consistent theory that the physics community agrees on? I think the answer is no. If that's the case, should we be trying to explain it to the public?

Ich

If he meant vacuum energy, there's an appropriate saying where I come from: you can't misguess as badly as you can miscalculate. (my translation, feel free to correct it)

Matterwave

Even with renormalization the vacuum energy calculated by QFT is something like 120 orders of magnitude off from the real value...I don't think we can exactly explain something even physicists don't know much about to the general public...

solarblast

To be specific,

"It is important to realize that in physics today, we have no knowledge of what energy is ... It is an abstract thing ..." -- Richard Feynman

In his Character of Physical Laws, he pretty much suggests it's an accounting system. He gives some simple examples with a child misplacing balls in his room, and his mother figuring out the number missing. Galileo hints at something abstract with a ball rolling down a ramp and up another ramp to the same height (almost). That was probably the beginning of the idea. It was something begging for an answer. Another related idea is entropy. It's a property of matter, and one can talk (briefly!) about orderliness. The, of course, there's E=mc**2.

I guess for the public or layman, some hand waving is needed. My need is really not to lecture or provide a simple talk exclusively about energy. It's to give some credence to it when generally talking about with respect to space and the universe.

axemaster

To be fair, most of the public thinks of energy as glowy flowy stuff. As in "it's made of pure energy!!!" Most people also don't understand calculus or what an integral is. So trying to explain vacuum energy to them in a physically acceptable way is probably off the table.

The only way I can think of is to say something like: "When you look really closely, space is like the ocean; it has waves that push and pull, but over time they push equally in all directions, so if you zoom out they aren't really noticeable."

solarblast

Not a bad analogy. I may use it.

Chronos

Under modern theory empty space has potential energy. But, you cannot extract useful energy from empty space, it is already at the lowest possible energy state. Calling it zero is merely an accounting convenience. It does not matter what it 'really' is, only that it is zero relative to matter.

Nabeshin

Isn't this discrepancy only when you try to equate the vacuum energy with the observed dark energy?