Tag Archives: quantum

Can #thedress kill a cat?

It seems only fitting in the week that a dress of a many hues broke the internet, that we question the very nature of objective reality. Our entire Year 9 cohort at Burgess Hill School for Girls have been deconstructing classical mechanics and looking at the world with a quantum eye for the last two months. What is at question with #thedress is the way in which we human beings view the world, and for this I want to look at it in the way that Schrödinger looked at his cat.

Not a black/blue dress

So here is the issue – a grainy image of a dress appears on Tumblr. There is a debate about its colour. Some people see it as blue and black. Some people see it as white and gold. I see it as blue and gold, which apparently makes me unusual. The dress goes viral in a way that nobody would have possibly predicted, helped in no small amount by the likes of Taylor Swift proclaiming that she is “…confused and scared…” by the idea that not everybody sees the same colours in the dress.

Taylor swift in an existential crisis

Neuroscientists tell us that this difference in perception is due to the way that the brain makes sense of the light and shade picked up by the rods and cones in our eyes, and the Wired team posted a nice article where they confessed to (brief) “…existential spasm of despair…” by the difference, before then going on to explain the differences in terms of white colour balance.   All of which may be true, but I am most interested in why it has so quickly disseminated across most of the internet-connected globe, and I would warrant that Tumblr is no doubt grateful for all of the traffic that it generates.

Is it the fact that people are recognising that those thing which we perceive, and generally assume to know to be true, are in fact not necessarily true?  Is it the fact that we have had a mirror held up to our concepts of colour and knowledge itself? I know that the dress is blue and black, but I also know that the original image of the dress – white balance washout or not – is not in fact blue and black; it is blue and gold.  To me.  And yet to other people who are looking at the identical image, on an identical screen, stood right next to me – well they perceive it as white and gold, or blue and black.   To them they know it to have a different colour scheme. Interestingly, many people have perceived it as one colour on the Thursday, and then an entirely different colour the following day, and are now in a constant perceptive flip-flop that is at the very least confusing and at most poses quite deep questions.

I would therefore like to turn to Erwin Schrödinger and his cat – a thought experiment which he devised in 1935 to explain the problem of the Copenhagen Interpretation of quantum mechanics to what we normally perceive as reality.

Here the fictitious cat is placed into a sealed box, and attached to the lid of the box is a mechanism which will release a radioactive atom that, when activated, will instantly kill the cat inside the box. We do not know if the cat is alive or dead inside this box (Schrödinger could have placed an already dead cat in the box, which would be rather impolite) until we look inside – and it is the act of looking inside the box that makes the cat alive/dead. In other words, our entire knowledge of the cat is that it is both alive and dead at the same time until we open the box. In quantum mechanics the cat is in a state of superposition – both alive and dead simultaneously. This is clearly absurd. The cat has either one state or another – it patently cannot be both, and it is not an extra in The Walking Dead.   Only when the person holding the box opens it does the cat’s state change from being both alive and dead, and it actually becomes dead.

Schrödinger devised this sceptical scenario in order to highlight this absurdity, and the absurdity of what the then-new paradigm of quantum mechanics implied for science, and for reality itself.

However in the ensuing years quantum physicists have picked up this scenario and proclaimed it as quite real – real in the sense that it is in fact now possible for entities at the microscopically small scale – at the scale of photons and electrons – to be in two different states of reality at the same time. They have moved away from a thought experiment about cats, and onto actual reality itself – by splitting and entangling electrons into qubits that hold these multiple states of reality, they are now creating quantum computers with potentially stunning computational potential. Such computers are at the early stage of development, but are advanced enough to be bought by the likes of Lockheed-Martin, Nasa and Google.

What, though, does this say about #thedress? Let’s imagine a Schrödinger dress. A picture of the dress goes out over Tumblr. Different people perceive the dress in a different way – in other words they interpret reality in different ways. Many see blue/black, many see white/gold, I see blue/gold.   The dress is now holding more than one reality, like the cat in the box. Somebody needs to open the lid and look inside the box – at which point the superposition states of the dress will collapse into one real state.

This has already been achieved – the company who made the dress, Roman Originals, have already opened the box and told us that the dress is blue and black.

Clearly not white and gold

Can I see that the dress above is blue and black?  Of course.  Can I see that the dress below is blue and black?

Not a black/blue dress

Of course not. It is not blue and black. It is plainly blue and gold. How can other people look at this image and not see that? I know what colour light blue is, and this image has light blue bands, not white. White? Certainly not white. I know what black is, and I know what gold is. The other bands are golden. Clearly not black. Not to my perception of reality.

Now here is the rub – the box has been opened and Schrödinger’s dress has collapsed from multiple potential states of reality, multiple potential colours, from superposition, and it has collapsed into blue and black. I know this. Yet I also know that the image that I perceive up above this text has not collapsed into blue and black. It is still blue and gold.

In other words, despite what I know and what I am teaching about quantum mechanics, the dress that I am observing right now has not collapsed into one state or the other. It still retains multiple states of reality for me, and it seems to for many people.  Multiple states of reality for the people who are viewing the image – just let the sit in your mind for a while.  Am I really suggesting that multiple different realities might exist, even as we are flipping around from one perceptual reality to another?  Well, yes.

Who can save me from this existential crisis? Answers on a blue and gold postcard please.

(This article was inspired and edited by Mrs. G. Humphrey)