The outcome of this simple experiment is quite shocking because it suggests light behaves differently when being observed. But to understand the science of the Double Slit Experiment, first take a look at the way particles and waves behave in different circumstances.
Firing light at a plate with a single slit in the middle always leads to the same result: a vertical line on the back wall. This is because some light reflects off the plate, while some go directly through the slit and land on the wall predictably. Adding a second slit should therefore create the same result: two vertical lines on the back wall.
Waves are a little more complex; so think of them as like ripples in a pond. When the ripple collides with the plate, only the apex passes through the slit and radiates out. It strikes the back wall with the most intensity in the middle – directly in line with the single slit. This is similar to the single vertical line created by firing particles.
But, sending waves through two slits has a completely different effect. As the top of one wave meets the bottom of another wave, they cancel each other out. This creates an interference pattern on the back wall. There are now lots of vertical lines across the wall where the many little waves hit it with the highest intensity.
In the Double Slit Experiment, electrons are fired at the slit in much the same way. A single slit causes a single vertical line of electrons along the back wall. But when the electrons are fired at two slits – and here comes the kicker – the result is an interference pattern. Why are these tiny bits of matter, fired individually at the wall, suddenly behaving like waves? What are they interacting with?
For some physicists, the conclusion was inescapable. The tiny electron arrives at the plate as a single particle, becomes a wave of potentials, goes through both slits, and interferes with itself. Mathematically, this theory is even more bizarre. The electron goes through both slits – and neither. It goes through just one – and just the other. By this reckoning, the Double Slit Experiment suggests that every possibility actually occurs in parallel worlds.
But this was just a theory, so physicists put up a measuring device – an observer – next to the plate to see which one the electron really went through. Amazingly, the electrons returned to behaving like particles again, creating two vertical lines on the back wall. The act of observing the quantum world actually changed the outcome! In short, the electron "decided" to act differently, as if it were "aware" it was being watched. The observer collapsed the wave function simply by observing.
So this is sort of like schroedingers cat, is that right?
ReplyDeleteDude. serious mindfuck. what does it mean?
I guess my biggest question is what significance scientifically? I guess it informs our understanding of the nature of light -- or is it really just light? This experiment seems to be saying that the nature of anything depends on how it is observed, suggesting that several or many different laws apply at certain levels of experience; that experience, in fact, dictates truth... Is that a reliable interpretation of the meaning of this experiment? What do you guys think?
It reminds me of an experiment I studied in cognitive science last year.You've probably seen it before but you can find it here:
http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html
If that doesn't work look for the "adelson illusion"
The explanation states the illusion functions because the visual system operates wholistically, refusing to take in visual stimuli as distinct elements. It always must account for the context within which that element, in this case a color,occurs.
But the big reason I bring it up is because I got to reading the paper, and saw that he begins the paper with a quote by John Ruskin, which i really like:
"Every light is a shade, compared to the higher lights, till you come to the sun; and every shade is a light, compared to the deeper shades,till you come to the night."
Nothing is just what it is; no one just is.
...
Unless you're the Joker.
When you say that experience dictates truth, I think that statement is already kind of understood: anything that we know about this so-called "world" is only as it presents itself to us in our experience. The world COULD be something that's not like what we experience, but that would be largely irrelevant as there would be no way to investigate such a possibility.
ReplyDeleteAs for the scientific significance of this experiment (and there are many), I think it's that it shows how our understanding of physical properties are/could be wrong: particles don't have to act like particles but instead act like waves. This whole idea is pretty radical, as you wouldn't expect a baseball to travel in ALL directions when the pitcher pitches it. Yet, we have evidence that such a thing does happen, but we also cannot directly observe the phenomena.
Also, to say that observations (experience[?]) dictate truth might need a bit more elaboration. To say that a photons act like waves when there is no observer present doesn't make the ensuing interference patterns false. We have the evidence, but we're just not able to directly observe how the evidence came to be (because, of course, they start to act like particles when we try). It's like we're playing a seriously fucking frustrating game of red-light-green-light, and we're playing with the red-light-green-light God.
There are many more scientific virtues that arise from this, like entanglements (?), and other stuff like that I think maybe.
This post is a little more physical than philosophical. I'm gonna do a follow up post on Schrodinger's Cat...
ReplyDeletePlease do!
ReplyDeleteAnd also, apologies again for my tendency to pervert already complex material into terms clearly non-analytic and only vaguely philosophic -- but I also beg you to remember the flexibilities a blog of unlimited potential has in accommodating interests of all kinds.
Only the fist few paragraphs of this are relevant to our discussion.
Even that is not really of good quality, btu better to post incomplete than never post at all type thing, so here it is.
I very much hope I have given you no reason to expect that I might find interest in realizing that an observation, by definition, requires a conscious experience in order to occur. Observations require observers and observers require an experience to observe a particular phenomena. No arguments there.
The statement "experience dictates truth" does not indicate (though it does assume) that the observation of truth requires an experience and instead asserts the nature of an experience determines what is true about the observation. The double-slit experiment makes no fundamental change in the elements of the experiment besides its manner of observation, which was only expanded. However, it is expanded in such a way that would “reveal” the truth of its mechanisms. When it is observed in a way that does not provide information adequate to establish a conclusion, its results are repeatedly conclusive. The truth of a phenomena changes iff the nature of its experience changes. Truth depends on experience not just in order to be perceived, but to exist in any particular way at all. We would not be the passive-though-highly- intelligent receptors of truth, knowledge, scientific fact, whathaveyou that we think we are.
So when I say that this experiment expresses the possibility that experience dictates truth, I mean that it inverts our assumption that we exist relative to the world, essentially anthropomorphizing the basic structure of the universe. God was not here first, the universe was not here first, we were here first: we are more than reflections of the world; the physical, scientific world instead a reflection of us.* Perhaps the idea that the world is independent of us is as mistaken as the idea that the world was created for us.
I really don’t find the science-fictiony possibilities of this interesting so much as I do its analogical resemblance to the our everyday experience. Like in the Adelson, everything that is the same is different in context and everything that is different is the same in respect to the standard (insert Ruskin quote here.)
It’s a small thought, but it’s a true one. That’s enough.
Anyway, that was the thought I was referring to – I hope it is in some way clear.
partially related thoughts In some of my other research, I also found that the devices used to measure the electrons were turned off in one iteration of the experiment -- the result (unbelievably) saw the electrons return to a wave-form pattern. The physical presence of the devices themselves was not the issue -- it was that they were observing the phenomena.
ReplyDeleteOf course, the possibility that quality manipulates quantity, that feeling orchestrates logic, sounds more than unlikely –though, still, it is not an illogical implication of the experiment. Nevertheless, among almost every other piece of scientific knowledge we have, this sort of occurrence is unique (that brings a question to mind: is this physical valence common in quantum physics? I'm sure its uniqueness in this respect is the source of its fame, but just thought I'd make sure.) This scarcity, while it might imply a critical flaw in our overall understanding of things, is still overwhelmed by the likelihood that there is an independent truth here that we, for some reason, cannot currently access. So, assuming for the moment that there are indeed ultimate universal truths and laws in the universe, even in the face of these startling results yields as little risk as it necessitates any overall alteration in our current understanding of things.
(On an aside, this makes me wonder whether methods that physically remove the measuring devices were attempted, perhaps reducing the likelihood that the electrons would be "aware" of being observed. Also hopefully in some sense provocative, I thought about the possibility that perhaps the electron only seemed to be going through one of the slits though it in fact remained going through both holes, neither hole, just hole #1 and just hole #2. Clearly not the case: the result itself changed. However, the result could be the product of a phenomena similar to the electron that simply "chooses" an appearance, though all possibilities are being fulfilled -- a possibility we know is not occurring because the result DOES change, but entertain my thought for one more moment -- this could mean that, in the same way we would appear as only a sliver of our bodies in the second dimension, that we are viewing only a part of a phenomena which has adjusted itself for existence in our dimension, forcing it to choose just “one” visible conclusion though several may be occurring.)
*I am aware that the theory of relativity says the our perception of the world is relative to our position (frame of reference) within it, but this only goes as far the manner in which the world relates to us; no physical change is occurring. Any material changes in the physical world are epiphenomenal (the sound of a bell to a passing train.)