By ghosts, I'm referring to creatures possesing characteristics normally associated with traditional ghosts/spirits. Things like:

  • Invisible (bonus point if they could choose to be visible)
  • Could phase through objects or teleport
  • Could interact with objects
  • Could shape-shift

They could be the spirits of the deceased, but other supernatural entities with similar characteristics also qualify, such as the jinn.

The idea of them being higher-dimensional beings is really neat, but I'm thinking of another possibility: what if they are based on virtual particles instead? After all, virtual particles are basically "there-but-not-really-there", yet still have physical effects eg. the Casimir effect. Are these creatures possible? My understanding is that virtual particles are basically background statistical fluctuations, but what if some behave non-randomly?

  • 2
    $\begingroup$ Virtual particles are not real. I would describe them as a mathematical artifact/construction to make working with the theory easier (although no one would describe it as easy). Here is a link to a question on Physics SE : What actually are Virtual Particles ? $\endgroup$
    – StephenG
    Jun 20 '20 at 19:25
  • $\begingroup$ @StephenG But these artifacts still exert physical effects (eg. Casimir effect) that can't be explained otherwise, right? It's a purely what-if scenario. Higher dimensions have never been proven to exist, yet it's still fun to speculate their effects in worldbuilding context. $\endgroup$
    – Ray Arifin
    Jun 20 '20 at 19:37
  • $\begingroup$ @AlexP Can you recommend a layman but accurate explanation for that? Virtual photon is the only explanation that I'm aware of. $\endgroup$
    – Ray Arifin
    Jun 20 '20 at 19:53
  • $\begingroup$ Virtual particles don't exist in the physical reality. The Casimir effect is real and physical, but it is not produced by the mathematical tricks used by physicists; it is produced by the the electromagnetic field, specifically by its quantum nature. (To put it another way, quantum fields behave as if the interactions were mediated by virtual particles; which makes virtual particles a useful model, but does not make them physical.) (Such non-physical models are common; for example, the "light rays" on which geometrical optics is built.) $\endgroup$
    – AlexP
    Jun 20 '20 at 19:54
  • $\begingroup$ "Although the Casimir effect can be expressed in terms of virtual particles interacting with the objects, it is best described and more easily calculated in terms of the zero-point energy of a quantized field in the intervening space between the objects." (Wikipedia) "[Virtual particles] never appear as the observable inputs and outputs of the physical process being modelled." (Wikipedia) $\endgroup$
    – AlexP
    Jun 20 '20 at 19:59

Only very small ghosts.

Every phenomenon where the notion of virtual particles is mathematically useful is very small. The Casimir effect for example requires the two plates to be very close to each other. Since ghosts are usually people sized it sounds silly to try and explain them using virtual particles.

  • $\begingroup$ What if there's a lot of them? If I set an arbitrarily large number of plates and hooked them up with wires to a generator, I could extract a significant amount of energy (at least until the plates stick to each other), right? $\endgroup$
    – Ray Arifin
    Jun 20 '20 at 20:21
  • $\begingroup$ Maybe? I'm not sure. I suppose you could have a village where there are thousands of microscopic ghosts that slowly drive the townsfolk mad but never appear as a white spectral figure. $\endgroup$
    – Daron
    Jun 20 '20 at 20:55
  • $\begingroup$ I don't see a ghost. I see a big contraption with a lot of plates plugged into...hey! Who unplugged the Xbox! $\endgroup$
    – user535733
    Jun 20 '20 at 22:41
  • $\begingroup$ Maybe your ghosts mostly inhabits on the surface of blackhole, twist: they become real when they die ;D $\endgroup$
    – user6760
    Jun 21 '20 at 2:36
  • $\begingroup$ i dont quite understand casimir effect and such but is it possible for this tiny ghost to join or interlocking to create bigger image ? akin to tv pixel or cell interlocking or school of fish or flock of birds? $\endgroup$
    – Li Jun
    Jun 21 '20 at 6:22

Virtual particles are a mathematical abstraction for describing the interactions of real particles via their coupling to other fields.

So, your ghosts would be made of non-free fields.

Which is functionally equivalent to being made of normal, real particles.



You tagged your post . Their are no ghosts in reality. There are no virtual particles in reality. So, no, your ghosts can't exist.

If we presume ghosts exist, we're still stuck with virtual particles. What definition are you using?

1 : being such in essence or effect though not formally recognized or admitted
2 : being on or simulated on a computer or computer network print or virtual books a virtual keyboard : such as
 a : occurring or existing primarily online virtual shopping
 b : of, relating to, or existing within a virtual reality a virtual tour
3 : of, relating to, or using virtual memory
4 : of, relating to, or being a hypothetical particle whose existence is inferred from indirect evidence

(1) is still a "no" because "in essence" isn't enough of a conjecture to establish a rule.

(2) is still a "no" because a computer simulation isn't real by definition. (Or is it?)

(3) is still a "no" because a computer wasn't declared to be involved in your question.

(4) Here we go. Maybe we have a "yes" here. If we declare the ghosts to exist, then the ghost is prima facie evidence of a hypothetical particle whose existence is inferred indirectly from the ghost!

Except that it leaves us with a hypothetical particle that is assumed to exist simply because ghosts exist... which leaves us with the only possible answer:


Because a hypothetical or virtual particle solves the problem if you, the author, declare it to be so.

What were you asking again?

  • $\begingroup$ Virtual particles are definitely a real thing: en.wikipedia.org/wiki/Virtual_particle $\endgroup$
    – Ton Day
    Jun 21 '20 at 11:32
  • $\begingroup$ @TonDay Thanks for the link! I was unaware of their use in physics. However, even that article explains that virtual particles are not "definitely a real thing." What they are is definitely a useful mathematical construct to help physicists explore the interaction of real (actual, existing) particles. In other words, physicists are using definition #4. $\endgroup$ Jun 21 '20 at 15:46


Virtual particles are real. Ghosts are not real. Therefore we cannot use virtual particles to explain ghosts.

But I thought virtual particles were. . . well, virtual.

They are virtual in the sense that they are not particles. They are things that are like particles in some ways and unlike them in others. But they are as real as anything else.

In field theory there is a collection of fields that occupy all space, one for each fundamental particle. An electron is a special type of little butty wibbly wobbly bump in the Electron Field, that hangs around for a while and has enough energy to have a mass. Likewise a a photon is just a little bitty wibbly wobbly bump in the Photon Field (though photons don't have mass).

An important fact is that there are only so many allowed types of particles. If you have a bump with half as much energy it cannot form a half-electron.

When two electrons get near each other their wibbles interact in such a way that forces them apart again. However there is not enough energy in the interaction to create new particles.

Still the interaction behaves mathematically as though there are some things involved that are like particles but not quite. In particular they are very short lived and massless. Though there is no mystery involved since we know it's just wobbles in the field doing all the work.


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