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mfb- t1_je1a0gr wrote

If there is an electric field then it's not an ideal vacuum.

A field in that range is strong enough to produce electron/positron pairs from the energy in the electric field. It has some similarity to pair production from photons.

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pewpewbrrrrrrt t1_je1zbl7 wrote

I'm sorry if this is stupid, my understanding of what space/time is would mean there's no way to not have an electric field. Even if you made a vacuum with no charge you would have to use an electric field to make the vacuum inside have no charge therefore there would always be an electric field.

Is that a flawed understanding?

Is an ideal vacuum a theoretical or mathematical concept that is technically impossible in our understanding of physics?

Thank you for any clarification, I think I have a good idea of high school level math + a high level of modern physics concepts so ELI16?

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LeN3rd t1_je2b1yf wrote

Ideal vacuum means there are no atoms/particles. Fields by definition are always there in all of space.

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QuentaAman t1_je6pbn0 wrote

But we're not talking about quantum fields here, right? I also think that's a wee bit too complicated for what he's asking about.

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mfb- t1_je40csp wrote

You can have an electric field strength of zero, that is commonly called "no electric field". You could argue that zero is the strength of the existing field, but that's just semantics. In practice you won't achieve a field strength of exactly zero, of course, but that's just an experimental limit.

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QuentaAman t1_je6oy0t wrote

You can shield against electric fields by using a faraday Cage. This is above highschool level but the wuick answer is that, using maxwells equations, you find the the electric potential inside such a cage is exactly 0 no matter what charges there may be outside the cage. And since the electric field is the gradient of the potential (again, sorry if that's too advanced for you) it is also 0.

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[deleted] t1_je2eekv wrote

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axolotl_afternoons t1_je2rt7f wrote

There's no matter present, but there's electrons, protons, and ions? These things are not matter?

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[deleted] t1_je0zxu5 wrote

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remarkablemayonaise t1_je16aks wrote

c=1/√(ε0μ0) shows the speed of light is related to the electric and magnetic field spontaneously generated by photons in a vacuum. I've probably mixed relativity with quantum theory there though...

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RockinRobin-69 t1_je1espn wrote

Yes. I didn’t want to get into “there is no such thing as a vacuum” because of quantum. While true it probably doesn’t affect dielectric constants.

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El_Sephiroth t1_je8y2on wrote

As I understand it, dielectric breakdown voltage is the energy necessary to disrupt an insulator into a conductor. Therefore, if you have a perfect vacuum, there is no matter to disrupt. But, a high enough voltage could still create electron-positron pairs out of the vacuum and therefore make a conductor in something empty. It's called schwinger effect. It is only a prediction of quantum electrodynamics.

So if there is nothing there, electricity could pass through when "matter" (here electron and positron) are created in it.

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[deleted] t1_je2w6a6 wrote

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mfb- t1_je40l8w wrote

OP is asking about the Schwinger limit. This has nothing to do with walls.

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[deleted] t1_je4dylt wrote

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mfb- t1_je4eu6y wrote

In practice you focus beams of electromagnetic radiation to collide with each other. You can't reach fields anywhere close to the Schwinger limit with charged walls, so again, this has nothing to do with walls.

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