What If Ghosts Were Real?
If we are correct about the laws of physics, then ghosts can’t exist. But some people are insistent that they’ve directly interacted with ghosts. Is there a way ghosts could exist if we modified the laws of physics a bit?
Okay, what are the properties that ghosts need to have?
- Ghosts are coherent entities with bodies. (Maybe they have heads and arms and legs, or maybe they’re a vague cloud shape, but they definitely have something that you could call a body.)
- Ghosts are invisible.
- Ghosts can pass through solid objects, but they can also knock over lamps and stuff (as long as doing so would be sufficiently spooky).
There are already invisible things that can pass through solid objects. For example, neutrinos. But you can’t have a body made of neutrinos because the particles in your body will immediately scatter all over the place and then you won’t have a body anymore. So ghosts must be made of something else.
If ghosts can pass through solid objects, that means they don’t interact via the electromagnetic force. But something weird has to be going on with gravity. If your feet didn’t interact with the ground, you’d fall straight through to the center of the earth. But ghosts don’t do that.
Maybe ghosts aren’t affected by gravity. But the earth isn’t still: it’s revolving around the sun at 67,000 miles per hour (109,000 kph), and it’s constantly turning in its orbit. If ghosts aren’t gravitationally bound by the sun, why don’t they go flying off into space?
I can see two possible explanations:
- Ghosts don’t interact gravitationally, but they can move super fast to keep themselves in the same spot relative to earth.
- Ghosts do interact gravitationally, but they can make the bottoms of their feet interact electromagnetically with the ground to prevent themselves from falling through.
The first one doesn’t seem likely to me. The ghost of a 15th century Baron who’s haunting a mansion doesn’t know anything about how the earth’s orbit works, why wouldn’t he just get lost as soon as he turns to ghost-form?
The second explanation brings to mind a testable hypothesis. We put sensors on the floor of the haunted mansion, and that way we can tell when a ghost walks over them.
What are ghosts made of? Ordinary matter is made of protons, neutrons, and electrons. Ghosts can’t be made of those, or else we’d be able to detect them. They can’t be made of dark matter, or else they’d fall through the ground (and they wouldn’t have bodies). Ghosts must be made of some new type of matter that doesn’t interact with the electromagnetic force, but does hold together somehow. That means there must be an as-yet-undiscovered fifth fundamental force that holds ghost bodies together.
Coming back to our ghost properties: ghosts can pass through solid objects, but they can also interact with objects when they want to be spooky. So it’s not as simple as “ghosts don’t interact electromagnetically”. (If that were true, ghosts would have no observable impact on the world at all, and we would have no reason to believe they exist.) Ghosts can interact electromagnetically, but only when they choose to.
That’s quite a puzzle. Ghosts can use their consciousness to turn on and off the electromagnetic interaction at will. I can’t think of how that’s possible, so let’s just move on.
There are two important, but subtle, properties of ghosts:
- Ghosts can see.
- Ghosts can move.
Obviously ghosts can see and move, right? But these properties have some surprising implications.
- If ghosts can see, that means ghosts’ eyes can detect photons.
- If ghosts can move, that means they’re getting energy from somewhere.
The first implication means that photons affect ghosts, but ghosts don’t affect photons. Either that, or ghosts do affect photons, which means we should be able to detect ghosts’ presence by shooting photons at their bodies—which is a sciencey way of saying “we can see them”.
If ghosts can see photons but photons can’t see ghosts, then that means photons can create some sort of motion inside ghosts, but that motion doesn’t come from the photons. In other words, energy is coming from nothing. The fact that ghosts can move—and knock over objects—without any external energy source also indicates that ghosts can create energy from nothing. The Law of Conservation of Energy does not apply to ghosts.
That gives us a testable hypothesis. If ghosts can create energy out of nothing, then we should be able to detect that energy. It’s a bit tricky to test, but what we can do is put a haunted house into some sort of sealed chamber where we precisely measure all the energy that goes in and comes out. If ghosts can create energy, then we should see more energy coming out than going in.
I’ve come up with two testable hypotheses so far. Can you think of any others?
What does it mean to be open-minded?
On a few occasions, I have been accused of being “closed-minded” for denying that ghosts could be real. But what is open-mindedness? The sort of open-mindedness I care about entails pursuing the implications of a belief.
Suppose I were to entertain the possibility that ghosts were real. What would that imply about the rest of my beliefs? What would I need to be wrong about? Those are the questions I wanted to answer with this essay.
The fervent ghost-believers I met never seemed to have much curiosity about what the existence of ghosts might imply. How would ghosts be intangible, but without sinking to the center of the earth? If they’re intangible, how can they knock things over? If people sometimes observe ghosts in their haunted bedrooms, then it should be possible to observe ghosts in a lab experiment, right? How would you set up that experiment?
Open-mindedness is about being receptive to different ideas. An important component of receptiveness is curiosity: if this were true, what else might be true as a consequence? In my experience, people who accuse me of being closed-minded aren’t curious about what their beliefs imply. If you do a curious investigation of ghosts, like I tried to do above, you can end up in some interesting places.