Currently, in the Science Gallery, there is an exhibition on illusions (https://sciencegallery.com/illusion). One piece, by artist Matt Kenyon, is the work ‘Supermajor’. Here is a video of that work from another exhibition:
I think this is the simplest description of what you see: a number of drops rising out of a pool of oil and going back into a hole in a tin can above it. The drops seem to be opposing the fall of gravity, moving in the opposite direction to its pull, rising not falling.
Given this is a video, you might think there is post-production here. You could get this appearance on the film if:
- The temporal order of filmed frames is reversed: someone took the film and reversed the order of frames: what happens first (such as the drop being at the hole) seems to come last on the film, and what come last(such as the drop being at the pool) seems to come first.
- The film is upside down: The drops are falling, not rising, but the camera is upside down. What seems up is in fact down; what seems to fall up is falling, in fact, down.
In both cases, you see falling drops which, because of the film, seem to be rising. In the absence of such post-production, you would see the drops fall. If you saw it in real life (as you can until September in the Science Gallery), then you would see the drops fall.
But there is no post-production here. The video is just a straight (and right side up) shoot, with the only effects on it due to the normal functioning of the camera. And the strangest feature of what you see — that of the drops rising — is visible in real life. If you go and look at the piece in the gallery, you will see the same thing. In fact, it is more pronounced; there is no appearance of flickering in real life.
So what are we seeing here, when we actually stand there in front of it? Are we really seeing drops rising up freely through the air to go back into the can? How could that be?
Given you stand where the recorder is in this video, and are seeing pretty much what you see here in the video, So what explanations might you have for what is apparent here?
There is no discrepancy between appearance and reality here
There are droplets of oil rising up freely and unconstrained from the pool, just as they seem to do. They are ordinary droplets, moving as they’d move if they were falling. The only difference is that they are rising instead.
— This is not what is happening. There is something else going on. But you might have a view of the world which allows this. If you do, then I take it there is no reason for you to think that there is an illusion here. It is not something common that you’re seeing, but still: it happens sometimes, and there is nothing particularly to worry about.
— This view is worth keeping in mind, even if it is not the case that the drops are rising. That something is an illusion requires that what appears to be happening is not happening. If it is happening, then it is not an illusion; appearance and reality are the same.
— Also, that something rarely happens is not sufficient to call it an illusion. Feats of superhuman endurance (such as David Blaine’s living buried in a box for a week) may be rare, but they are not illusions. Nor would a 100m meteorite strike on the Earth be an illusion if it happened.
— Yet, I might not be able to predict either, nor might I quite believe it is happening when it does. Still, if it is happening, and it seems to be happening, then it is not an illusion.
— The point is this: what is real and what is not real do not correspond to what is common(or likely) and uncommon (or unlikely).
— But, still, this is not a rare case of ordered levitation by inanimate drops of oil. There are not drops of oil rising into the box from the pool. There is a discrepancy here between how things seem and how things are.
A. Some Possible Illusions
1. Some unknown force is pulling them up in a straight line
The artist has managed to generate a local anti-gravity field/a localised unconstrained air vacuum, or something similar, such that drops caught in the field/vacuum are pulled into the air, counter-acting the gravitational pull. The illusion is that there is no counter-acting force or vacuum apparent in the exhibit.
— There is no force pulling them upwards here. Certainly, no science fictional force here (actually, is a localised unconstrained vacuum science fiction or fact? I don’t know).
— In fact, the drops are not floating freely up into the can.
2. The illusion is that these are merely drops of oil.
They are not drops of oil. They are upward moving entities of undisclosed composition. (Or, if one is open to the fantastical, they are magical creatures which can fly and turn invisible which have been trained, paid or otherwise encouraged to become visible and fly up in formation into the hole).
— Yesterday, in Trinity (where this exhibition is), I heard a small child complain to her mother ‘mooom, you said this was like HOGwarts’. Unfortunately, for that child, her mother and this explanation, this isn’t Hogwarts.
— All you are seeing is oil. There is no magic here.
— But in one sense, yes, what you are seeing is not merely drops of oil.
There is a known force, like string, moving upwards from the pool to the hole above. The string is dragging drops fixed to it up out of the pool and into the can.
— There is no string involved here. There is nothing like that, nothing non-oily holding the drops together between the pool and the hole.
— All that is holding the drops in the order they appear is momentum and the force of gravity.
4. Mirrors or some other orientation-distorting medium lies between the observer and tank
The drops seen rising are falling, but we see them from a different orientation to how we seem to see them.
— There are no mirrors involved here. The exhibit is at the same orientation relative to the observers as it seems to be: the top of the can relative to the pool is in the direction of your head relative to your feet.
— Some of other exhibits use mirrors, and very effectively, to create illusions. In such mirrors, what seems to be orientated in one direction are actually orientated in another,
E.g., [WARNING: THIS SPOILS THE EFFECT OF ONE PIECE IN THE EXHIBITION]:
The text in one exhibit upstairs seems to be upright, lying in a vertical plane in front of observers, when in fact it is above the observers lying in a horizontal plane (and reflected on a mirror).
A.1. Time-related Illusions
And now some time-related illusions:
5. The drops we see rising are falling, but time is reversed
We are seeing individual drops fall into the pool. But we see it happening backwards in time., Somehow, the artist has managed to reverse time locally in that region so that the order of events is reversed. The illusion is that time is not reversed locally. So,
(a) We seem to see the drop enter the hole after rising up from the pool.
(b) But in fact, we are seeing the drop enter the hole before rising up from the pool.
(c) What is locally ‘before’ for the drops is, for us (and other locations) ‘after’.
What happens first (locally) happens last (in the outside world), what happens second happens before what happens first, what happens last happens first, what happens second last happens after what happens last.
(d) Otherwise, everything is as it seems to be: these individual drops are falling slowly through the air into the pool. So the only discrepancy is in temporal order.
— Some physicists and philosophers of physics allow this discrepancy of order between different locations. Indeed, some even deny that reality has any ‘global’ temporal order to it. Temporal order is local at best. This is, some claim, motivated by scientific theory: first, there is no inherent order to physical descriptions of the world; and, second, by the seeming exceptionless correlation between global entropy and temporal order.
— If you have such a view of reality, e.g., that there is no, or at least no global, temporal order to the world, then I think you are perfectly entitled to invoke it in your explanation of phenomena in the world. That we get the ‘wrong’ order here is illegitimate if you deny there is any real order out in the world anyway; there is no ‘right’ order. (Alternatively, if you take a view that there is no global order, but there is local order, then there is probably a case that the drops can be in the wrong local order).
— Anyway, there is still need here to explain the appearance of temporal order in the movement of the drops, even if it is the wrong temporal order.
— And there is no need for such elaborate explanations here. There is no reversal of temporal order to the drops. There are drops falling between hole and pool; we do not see that fall in reverse.
[This is a variation of ‘2’ or ‘3’ above, depending on how science-fictional or magical you think time-reversal to be].
6. The drops we see rising are falling, but our experience of time is reversed
Certainly, there is no reverse of temporal order where the exhibit is located. But there is a reverse in the temporal order of our experience of the drops.
Our experience of the drops is not located where the exhibit is located. Indeed, our experience of the drops is not even located when the exhibit is located; there is a small delay between the light leaving the exhibit and it striking our retina. There is a small delay between the striking our retina and the completion of the process that leads to our experience.
Somehow, in between the moment the drops fall and the moment we experience them fall, the order between each stage in the drops’ falls reverses. The events out in the world that come first are experienced as coming last, and those that come last are experienced as coming first.
— No, the delay between the events in the world and what happens in our brain as a result (of light from those events stimulating neural activity) is irrelevant. It is too short but, even if it was not, this is not what gives rise to this particular illusion.
— Just as there are no mirrors or time reversals, or any other kind of re-orienting devices in the world outside the brain or experience in this illusion, so there are no mirror-like or time reversals, or other kinds of internal re-orienting devices, in the brain or experience itself.
So what is happening? In the next post, I will suggest an answer for what is the actual illusion — the actual discrepancy between how things seem and how things are.
1. You can also see a video of it taken at the science gallery for me by friend Angharad Williams here: http://www.youtube.com/watch?v=VmMhqgpqV14
2. That you are standing only where the recorder is is necessary here because when you do directly observe it, there are various things you might do which means that you can test each hypothesis you have. You might easily move closer and push your hand into the stream, for example. Or, as the guides at the exhibition do, you might shine a bright steady light on it. What happens when you do these alter the plausibility of any of the explanations below.