# Star Trek Nerd: What are force fields and why dont we have them?

1. Jul 17, 2008

### taylaron

sorry about the fantasy factor here guys, but having a kind of barrier that can repel mass and be "mass less" without having any visible infrastructure would be quite valuable.

so the question is: What are force fields? (like the ones in star trek)
what would they compose of? and what keeps us from that technology?

i'm not talking about the effect that magnetic or electric fields have upon charged particles. simply the science of a fantasy (or is it?)
The effect of of repelling both protons, neutrons, and electrons.

*note
does any "theory of everything" in quantum physics (etc..) Predict such a phenomenon in the universe?

2. Jul 17, 2008

### D H

Staff Emeritus
The ones in Star Trek are of course works of fiction.
They most common construction material is http://uncyclopedia.org/wiki/Unobtainium" [Broken].
They're works of fiction.

Last edited by a moderator: May 3, 2017
3. Jul 17, 2008

### Hurkyl

Staff Emeritus
For further reference, see here.

Last edited by a moderator: May 3, 2017
4. Jul 17, 2008

### taylaron

I suppose you can't question the science behind a fantasy........

5. Jul 18, 2008

### masudr

Couldn't we have an electric vector field such as

$$\vec{E}(x,y,z) = -E_0 \vec{j} e^{-y/\xi}$$

where $E_0$ is a large positive number, and $\xi$ indicates how "thick" the repulsive wall is.

This would work because all the negatively charged electrons on the outer shell of all normal objects on earth will be greatly repelled if they approached the z=0 plane from the region y > 0.

Or have I made a glaring error somewhere? If it would work, maybe we could discuss possible methods of creating such a field (haven't thought about it properly, but can't think of any obvious candidates).

6. Jul 18, 2008

### HallsofIvy

An electric field does not only affect the "outer shell". All "normal objects on earth" are electrically neutral and contain as many protons as electrons.

7. Jul 18, 2008

### Staff: Mentor

Right. It's like asking why we don't have unicorns. They just don't exist and that's all there is to it.

8. Jul 18, 2008

### seycyrus

I have seen some efforts that create a localized plasma around an object, which interacts with objects and energy crossing the plasma.

Sorta looked like a force field from the movies.

9. Jul 18, 2008

### Staff: Mentor

I think it was Robert A. Heinlein who wrote a short story that went something like this:

Someone followed up on the observation that toilet paper and other sheetlike materials tend to tear everywhere except at their perforations (holes). He discovered that he could enhance the effect if he made the holes bigger. Continuing further, he removed all the substance and produced the strongest material known to man, which he dubbed "Nothing."

The best part was that he could take the removed raw substance, recycle it into new sheets, and use it to make more Nothing! :rofl:

Last edited by a moderator: May 3, 2017
10. Jul 18, 2008

### peter0302

We can at least say how a forcefield would NOT work. :)

A simple magnetic field doesn't work because macroscopic objects are not magnetically polarized.
An electric field wouldn't work for the same reason.

You certainly could make an invisible wall that would be very painful to step through, but it wouldn't physically block anything.

Yeah, so pretty much there's no known way of doing it. :)

11. Jul 18, 2008

### maverick_starstrider

what if you were emitting obscene amounts of photons such that the radiation pressure would repel any incoming object (although you'd also instantly cook everyone around you to, but that's just an added bonus)

12. Jul 18, 2008

### peter0302

It would be the momentum from the photons, and sure it would be possible to do. Do some calculations (E=hf) and tell me how many photons at, say, the infrared range (we want it to be invisible) we'd need to create enough energy to withstand a 100kg man coming at the forcefield at 10 mph. Then tell me how hot that would be.

Yeah, no.

13. Jul 18, 2008

### masudr

What if the parameter $\xi$ in my description above was 5 orders of magnitude smaller than the Bohr radius? The electrical neutrality of atoms wouldn't matter as we'd push back the electrons before the protons could even feel the field.

14. Jul 18, 2008

### peter0302

How would you make a field so narrow?

Also I'm not certain that works, since at any given moment the electrons have an equal probability of being on the wrong side of the atom, and therefore the protons would be attracted and it would all even out.

What you're talking about is artificially replicating what happens when solids touch. But that has more to do with the fact that the structure of the solid is stable and so resists being broken apart. There's a lot of QM involved. It's not simply the electrons from one block are repelling the electrons from the other block.

15. Jul 19, 2008

### Ivan Seeking

Staff Emeritus
There is ongoing work with "plasma windows" that somewhat resemble the fictional force fields imagined for windows and doors, on Star Trek.

http://www.bnl.gov/bnlweb/pubaf/pr/2001/bnlpr121101b.htm

Also, I would imagine that if not now, eventually it might be possible to design materials that can be powered for added strength. Something like this might mimic some of the properties of the fictional "shields" on Star Trek.

Last edited: Jul 19, 2008
16. Jul 19, 2008

### masudr

I'm not discussing the practicality of the method (just yet), just investigating if the method would work or not.

That's quite correct, but if the electron is on the other side as it were (or, I should say, in all the systems of the ensemble of systems where the electron is on the other side), the field would still be weaker at the proton site than the field that is affecting the electrons nearest the "wall of field".

Oh yeah, I hadn't thought of it like that (I did a course on electrons in solids last year, and absolutely hated it *shudders*). I suppose then we cannot aim to replicate that exact behaviour due to what you say. Still I don't see any obvious objections to what I've proposed (apart from the practicality).

17. Jul 19, 2008

### johanw

You would have to use gravity instead of electricity. This "reduces" the problem to create and structure artificial gravitation fields.

18. Jul 19, 2008

### peter0302

Yeah I confess I don't understand materials science that well myself at the quantum mechanical level (i.e. the different types of lattice structures or what have you). All I know is enough to know that it's not just a simple coloumb force at work. :)

Gravity!? How would you propose to make gravity repulsive?

19. Jul 19, 2008

### taylaron

what about the whole "white hole" concept? (compared to black holes...)
given this graviton actually shows up in the LHC; and we discover an anti-graviton; then mebe.....

20. Jul 19, 2008

### OAQfirst

If you're going to have an invisible force field, how will it stop a laser? That part never did look right in Star Trek.