Double Twit Experiment – What Brian Cox Gets Wrong

Posted on 2011/12/23


Feature Image - Double Twit Experiment

If you missed Brian Cox’s ‘A Night With The Star’ on Sunday’s BBC2 at 9pm, here it is:


When I used to teach secondary school physics, I was very disturbed by the reverence in which Cox was held (so to speak) by teachers and students alike.

I think the appreciation he receives is indicative of most what is wrong with physics education. A faulty presentation of scientific ideas that has greatly diminished and distorted the pubic perception of science.

Now, many of his supporters will be quick to point out that Cox appears to have greatly increased the public’s interest in science, and for this he is to be credited. I disagree.

To say you are ‘interested in science’ does not necessarily mean you understand it, or derive value from it. I think Cox’s science documentaries stupefy the public into remembering disconnected and obscure ideas they do not understand. This type of science teaching has little value.

Below, I use Cox’s recent lecture to critique his teaching, and (to compare) offer examples of better popularizers of science.

Here is a sketch of what is discussed:



  • A ‘Sense of Wonder’
  • Dinner Table Physics

Aspects of Teaching

  • Delivery
  • Demonstrations
  • Mathematics
  • Diagrams

Philosophical Considerations

  • Attacking Pseudo-Science
  • Description, Not Explanation
  • Agency and Desires
  • Logic and Imagination

Quantum Behaviour

  • Pauli’s Exclusion Principle
  • Double Slit Experiment



When the show began, I was entirely bowled over to find Cox hadn’t used his turn at ‘A Night With The Stars’ to deliver an astronomy lecture.

This missed opportunity reminded me of a story about the great astronomer Carl Sagan. When a young boy, he asked his parents, “what are the stars?” Unable to sufficiently answer Carl’s question, his mother furnished him with a library card.

She took him to the Brooklyn Public Library, and introduced him to the librarian … he asked for a book about the stars. The librarian knew what he wanted. She disappeared for a few moments, then returned with a book and handed it to Carl. He looked at it puzzled. It was about Hollywood actors, far from what he had expected. So Carl explained carefully what he really meant: the stars in the sky, not the ones in the movies.

 Spangenburg, Ray & Moser, Diane (2004) ‘Carl Sagan: S Biography’ p 7

It is this dual meaning of star that provides an interesting question: In Cox’s presentations, is the universe the star of the show, or is it Cox himself?

Was it a lecture, or a performance? Once again we see Cox centre stage, the star of the show. In a good science lecture, the star of the show is the universe.

Many unfamous science teachers also make this mistake. They confuse the delight in teaching someone a new idea with the feeling of satisfaction from convincing someone they are smart.

Just as some bad secondary school teachers seem to derive pleasure from intellectually impressing 14 year-olds, Brian Cox seems to get the same exhilarating feeling when talking to celebrities.

I’m not suggesting that his motivations should be purely altruistic. But the best educators of scientific ideas are facilitators for understanding –  they don’t get in the way. They are the guides through the cosmos: explaining complicated ideas and pointing at interesting things. All with the intention of allowing the audience a deeper comprehension of their world.

Cox seems to fall short in this respect, but it is not entirely of his own doing. He is persuaded to give personal interviews and appear on news quizzes. The media bosses are motivated by the sexual capital they perceive him to have and exploit this to fulfill their ratings first, and the public understand second.

A measure of the contempt Cox has for the audience, and the little interest he has in their education, can be noticed by how little preparation he has made. If you think he does a good job, take a few minutes to compare to the talents of these lectures, all available to view online:

Cox’s fame is an insult to the great educators of our age. His teaching has none of the poetry of Carl Sagan, none of the charisma of Richard Feynman. It is a disservice to audiences who are misled to believing they are learning something valuable. And, most of all, it is a sign of the insipid credulity of a British media, ill-educated in scientific ideas.



A ‘Sense of Wonder’

Each year, in the tradition of Michael Faraday, the Royal Institution gives a series of Christmas Lectures. In one of the lectures presented by Faraday himself, he offered the following motivations:

“Let us consider for a while, how wonderfully we stand upon the world. Here it is that we’re born and bred and live. And yet we view these things with an almost entire absence of wonder to ourselves respecting the way in which all this happens.”

Michael Faraday (1854) Christmas Lecture: ’The Chemistry of Combustion’ 

Faraday intended the word wonder to mean: ‘to think or speculate curiously‘.

First, there is the survival value for individuals and our species to take this point of view. The technology we have developed for the betterment of our lives can be attributed to the our working solutions to the problems we have faced.

Wonder is a valuable response to the world.

When I taught physics, I would my students that if they didn’t like it, it was either my fault, or their fault. In no way was it the universe’s fault.

I think it is a mistake, and one that Cox repeatedly makes, to suppose that you can show people some wonder, or tell them about it. Cox is not alone in this. The same method is used by several celebrity popularizers of scientific ideas. For example, when interviewed about his ‘Nine Lessons and Carols for Godless People show, the comedian Robin Ince said, “The only thing that will make people give up the comfort blanket of mysticism is by showing them wonder.”

The wonder Cox and others offer in replacement of mysticism is usually of the second definition of the word: ‘to be filled with admiration, amazement, or awe’.

I don’t wish you to think I suppose this perspective has no value. Indeed, this type of response is a rare example of the humility the human species so desperately requires. Carl Sagan was particularly brilliant at achieving this by demonstrating the scale of cosmological space and time.

But amazement and awe do not advance a person’s understanding of scientific ideas. And to settle for this response is to encourage your audience to be satisfied with felling bewildered and overwhelmed.

If you wish to encourage someone to take an intellectual interest in the cosmos, as any good novel writer knows: show; don’t tell.


Dinner Table Physics

Learning some physics allows a person to understand a great many occurrences while only having to remember a few simple ideas.

These unifying patterns (or, as physicists call them, equations) allow you to see the universe with greater cohesion. As Einstein said, theories ( synonymous with equations/hypotheses/laws/patterns) are ‘the delicate threads that connect our perceptions’.

For anyone who is not part of this community of physicists, there is still value in learning some of the basics. For example, know a little about optics allows a person to see the following things as containing similar details:

  • Rainbows
  • Glasses
  • 3D Glasses
  • Colours in oil slicks
  • Soap bubbles
  • Mirrors
  • The colours of CDs
  • Iridescent butterfly wings

In addition, learning optics will allow you to notice more about these things – life becomes richer.

Achieving this facility with the world is not a matter of what you think, but how you think.


What do we see with Cox’s lecture? We see obscure quantum mechanical assumptions used to introduce counter-intuitive effects and explain obscure astronomy.

I think I understand why it is a successful.

It appeals to the sort of person who listens to BBC Radio 4 only to remember this week’s ’factoids‘. The sort of person who will sit at dinner and swap these irrelevant nuggets while saying, ’isn’t that quite interesting?’, but has no desire to inquire further into the matter. One can witness the same level of credulity every Sunday in the pulpit.

It is the pseudo-intellectuals’ alternative to celebrity gossip.

In addition, there is an increasing number of the secular public who seem to think that there needs to be some declaration of their commitment to scientific thinking, even though they do not practise that type of thought themselves.

Just because a certain type of talk is championed under the word ‘science’ does not make it intrinsically valuable. Feynman puts it well when he said:

Newspaper reporters and commentators – there is a large number of them who assume that the public is stupider than they are, that the public cannot understand things that they [the reporters and the commentators] cannot understand. Now that is ridiculous. I’m not trying to say they’re dumber than the average man, but they’re dumber in some way than somebody else. If I ever have to explain something scientific to a reporter, and he says what is the idea? Well, I explain it in words of one syllable, as I would explain it to my neighbor. He doesn’t understand it, which is possible, because he’s brought up differently – he doesn’t’ fix washing machines, he doesn’t know what a motor is, or something. In other words, he has no technical experience. There are lots of engineers in the world. There are lots of mechanically minded people. There are lots of people who are smarter than the reporter, say, in science, for example. It is, therefore, his duty to report the thing, whether he understands it or not, accurately and in the way it’s been given. The same goes in economics and other situations. The reporters appreciate the fact that they don’t understand the complicated business about international trade, but they report, more or less, what somebody says, pretty closely. But when it comes to science, for some reason or another, they will pat me on the head and explain to dopey me that dopey people aren’t going to understand he because he, dope, can’t understand it. But I know that some people can understand it. Not everybody who reads the newspaper has to understand every article in the newspaper. Some people aren’t interested in science. Some are. At least they could find out what it’s all about instead of discovering that an atomic bullet was used that came out of a machine that weighed seven tons. I can’t read the articles in the paper I don’t know what they mean. I don’t know what kind of a machines it was just because it weighed seven tons. And there are now sixty-two kinds of particles, and I would like to know what atomic bullet he is referring to.

Richard Feynman (1998) ‘The Meaning Of It All’ pp 88-89

Cox does not seem to think that the public is dumber than they are, but he makes them dumber.


To compare, I think of the under-appreciated work of Adam Hart-Davis. During his long career, he has taken great care to weave historical context into clear explanations of every-day technology.

As an example, watch this brilliant half-hour presentation about lightning and the lightning rod:


Aspects of Teaching


The most prominent requisite to a lecturer, though perhaps not really the most important, is a good delivery ; for though to all true philosophers science and nature will have charms innumerable in every dress, yet I am sorry to say that the generahty of mankind cannot accompany us one short hour unless the path is strewed with flowers. In order, therefore, to gain the attention of an audience (and what can be more disagreeable to a lecturer than the want of it?), it is necessary to pay some attention to the manner of expression. The utterance should not be rapid and hurried, and consequently unintelligible, but slow and deliberate, con- veying ideas with ease from the lecturer, and infusing them with clearness and readiness into the minds of the audience. A lecturer should endeavour by all means to obtain a facility of utterance, and the power of clothing his thoughts and ideas in language smooth and harmonious and at the same time simple and easy. His periods should be round, not too long or unequal; they should be complete and expressive, conveying clearly the whole of the ideas intended to be conveyed. If they are long, or obscure, or incomplete, they give rise to a degree of labour in the minds of the hearers which quickly causes lassitude, indifference, and even disgust.

Michael Faraday ‘The Life and Letter of Faraday‘ (Compiled by Dr Bence Jones) pp 62-63

Cox rushes his speech and his tone has a peculiar cadence. His delivery makes each sentence sound like a mere aside, yet the punchline never comes.

His choice of words are sometimes grammatically ambiguous. When talking of protons, neutrons and electrons, he says ‘everything is made up of these same three absolutely identical particle.’ Does he mean these three particles are identical, or that all protons are identical?

He shows us a ‘million-pound’ piece of diamond and tells us that it is ‘diamond shape… that’s how it naturally appeared because it’s structure is like this [holding up tetrahedral model].’ I still don’t know what this means.

When describing electrons in an atom we are told ‘it’s tempting to think of those electron standing waves as waves with different energies inside the atom.’ Tempting to whom? To suppose the audience has the same train of thought as Neils Bohr, or indeed has understood anything so far, is wishful at best.


A lecturer falls deeply beneath the dignity of his character when he descends so low as to angle for claps, and asks for commendation. Yet have I seen a lecturer even at this point. I have heard him causelessly condemn his own powers. I have heard him dwell for a length of time on the extreme care and niceness that the experiment he will make requires. I have heard him hope for indulgence when no indulgence was wanted, and I have even heard him declare that the experiment now made cannot fail from its beauty, its correctness, and its application, to gain the approbation of all. Yet surely such an error in the character of a lecturer cannot require pointing out, even to those who resort to it ; its impropriety must be evident, and I should perhaps have done well to pass it.

Michael Faraday ‘The Life and Letter of Faraday‘ (Compiled by Dr Bence Jones) p 76

Cox nervously laughs at his own jokes and is distractingly self-mocking.

At one point he says ’I want to explain quantum theory, to you, in the simplest way that I can.’ Are we to suppose, on other days, he makes it difficult to understand? Or is this a plea that, are we to fail to understand, this is through no fault of his own?


The prose style is poorly consider, repetitive and probably improvised. When trying to convince us of the exactitude of quantum theory he says:

“Heisenberg’s Uncertainty Principle… says, precisely, that the more precisely you know a particles position, the less certain you can be of its momentum.”

Cox at 49:40

The confusing repetition of ‘precisely’ reminded me of a visiting lecture who came to my school to speak about the speed of light.

During the question section, I asked, ‘since the speed of light was recently redifined to depend on the length of the meter, why didn’t we just define it at 300,000,000 m/s rather than ludicrous 299 792 458 m/s?’ We could define the meter to be imperceptibly smaller and all would be well. A question John Gribbin asks in his book “Science: A History 1543 – 2001“.

The reply I received was very informative (but too complex for you to want me to reproduce it).

Unfortunately, he kept saying that the measurements of the speed of light had a “certain uncertainty”. He meant to say, particular uncertainty, but you can see why the students started to giggle at his garbled, but interesting reply.



To pretend that dropping sand through two holes in some wood is ‘doing an experiment’ makes physics look stupid. Cox has either included this for the sake of plumping up the number of demonstrations (and audience participation), or he has greatly underestimated the imagination of the public.

Feynman deals with the same considerations with one simple diagram and a few sentences (refer to the source material below).


Later, Cox tries to demonstrate standing waves on a string. He says ’it’s vibrating in a very particular way, because you’re [Simon] holding it still there, and you’re [Jim] holding it still there.’ Meanwhile, we can see them moving their hands up and down, as instructed. How are we to take this seriously?

When they try to get to the third harmonic, the difficulty of two people moving the spring becomes apparent. Anyone who has demonstrated this before will know that one person staying still works far better than two people flailing their arms around. It was ill-considered and under-rehearsed.

Then there is the innuendo catalyzed by Pegg and encouraged by Cox throughout this demonstration.

If Cox insists on masturbation jokes, then why not utilize the rich vocabulary already provided by the names of other lab equipment? For instance, he could have excited the string with a vibration generator, or demonstrate standing waves with Kundt’s tube. Need I go on? (Said the vicar to the…)



Before the show begins, Cox tells us, while having cosmetics brushed onto his smug face, that he’s ‘gonna make at least one unsuspecting celbrity do sums.’ (For those of you beyond our shores, ‘sums’ means mathematics.)

Why write up the Feynman path integral? Not even Feynman wrote up the Feynman path integral when lecturing to the public!

When he call up Jonathan Ross, Cox makes him stand there and listen while he make various estimates about the size and mass of the diamond in the box. What a missed opportunity to get Ross to do it. Does it not seem the wrong way around for the physicist to estimate commonly-encountered lengths and quantities, while the comedian is asked to multiply large numbers together?

Why are we to suppose Jonathan Ross’ life would be richer if he knew how to multiply number presented in standard form? Why should Ross know about Plank’s constant?

We then have to watch while Cox ridicules someone for not understanding an idea. And he is celebrated as the paragon of scientific educators?



Contrary to most of Cox’s previous educational presentations, we are deprived of the background of stunning landscapes and rousing music. Instead we find Cox ‘unplugged’ in the humble Faraday Lecture Theatre of the Royal Institution.

The nature of this historic setting perhaps explains Cox’s kitsch attempt at using a blackboard. If this is characteristic of his diagrammatic clarity, I do not envy his students.

For example, look at Cox’s attempt at drawing the arrangement of electrons in a hydrogen and an oxygen atom. It is bewildering, ambiguous, scruffy mess of arrows. It was so badly drawn, I almost felt I might un-understand chemistry if I continued to look.

To show what a little care and forethought can achieve, watch any of the free MIT lectures on physics from Professor Walter Lewin (pictured above).

For preparation, Lewin says, ‘I rehearse every lecture 3 times, in real time. With an empty classroom and empty blackboards, I write on the blackboard everything I will be writing down during my lecture.’ He says the preparation for this is around 40 hours per lecture.

And it shows. Lewin perhaps has the best command of blackboards in the history of science teaching. He is also aware of the purpose for drawing diagrams and utilizes them with extraordinary educational impact. His diagrams are unambiguous, colourful, precise and drawn at a comprehendible pace. In addition, he takes time to tell you what each line represents, although with his clarity this is hardly required.

Watching Lewin, it is clear Cox has much to improve upon. (Incidentally, notice the ease with which Lewin demonstrates resonance with a string.)


As an aside, Lewin also has an extraordinary ability to draw dotted lines with a piece of chalk!


Philosophical Considerations

Attacking Pseudo-Science

Opening his lecture, Brian Cox states:

‘I understand why quantum theory can seem a little odd… but that isn’t a license to talk utter drivel. … it describes the world with higher precision than the laws physics laid down Newton… It doesn’t therefore allow mystical healing, or ESP, or any other manifestation of New-Age woo-woo into the pantheon of the possible. Always remember quantum theory is physics. And physics is usually done by people without star-signs tattooed on their bottom.’

Cox at 4:09

Now, I know the motivations for such a comment. The separation (or demarcation) between science and pseudo-science is a valuable idea to convey, considering the enduring appeal of people such as Deepak Chopra. Chopra, who claims Hilary Clinton among many famous clients, has a very lucrative career in persuading people that quantum theory is the Western dual to ancient Eastern mysticism. Depending on the audience, he sometimes also make claims that quantum theory answers all philosophical questions about the mind and describes a process called ‘quantum healing’.

Here is an example of his work:

To compare, here are some of the the ideas Cox mentions during his 1 hour lecture:

  • Particles can occupy many locations (an infinite number) at once.
  • Atoms in our bodies shift position due to occurrences 1 billion light years away.
  • Diamonds are 3 billions years old.
  • A golf ball sized object has around ’3 million billion billion atoms’.
  • Atoms are mostly empty space.
  • Electrons can travel an infinite number of paths when moving from one place to another.
  • Diamonds can spontaneously jump out of boxes.
  • There are objects the size of planets, as massive as stars, ‘a million times more dense than water’ and made of pure diamond.

Now, if all this is true, you might ask: well, what is so strange about ESP and mystical healing now? How are we to tell whether a ‘bizarre prediction’ is a consequence of the latest physics, or ‘wishy-washy-drively-nonsense’?

If Cox was speaking about a some physics derived from our intuitive physical world (say, Newtonian gravitation) he might well appeal to our common-sense. However, when his own lecture is aimed at challenging our expectations, while introducing some very esoteric phenomena, intuition holds no currency.


In other words, Cox is appealing to an argument from authority. We hear how physics gets results, but Chopra’s claims are not ones that ask for measurement or experiment.

Cox probably thinks he has addressed this sufficiently by quoting Sir Humphrey Davy in the introduction:

“Nothing is so fatal to the progress of the human mind as to suppose that our views of science are ultimate; that there are no mysteries in nature; that our triumphs are complete, and that there are no new worlds to conquer.”

(Cox at 2:27)

As quoted by David Knight (1998) ‘Humphry Davy: science & power’ Cambridge University Press p 87

However, asserting the fallibility of scientific inquiry is different from demarcating between scientific theories and non-science. Furthermore, we hear Cox later say that the Pauli exclusion principle is an ‘unbreakable law of nature’ – a confusing statement to make in a lecture with such a humble opening quotation.


To offer an example of how to do it better, I am reminded of Carl Sagan’s Cosmos series from 1980. In episode 3: ‘The Harmonies of the World’, Sagan distinguishes between scientific astronomy, and non-scientific astrology.

If you wish to dedicate one hour of your life to thinking clearer about the universe, there are few better ways to spend it than in the company of Carl Sagan.


Description, Not Explanation

“Quantum theory is rather unfamiliar because it applies to small things because Plank’s constant is small.”

(Cox 48:34)

Plank’s constant is guessed from experiments conducted on a very small scale. To say that this number – this ‘fundamental constant of nature’ – is the reason for them being noticeable only at the small scale is to confuse description with explanation.

Let me offer an analogy. Why do objects keep moving until slowed by a force?

Many people might be tempted to say, ‘because of the inertia of the object’. However, this would be to over-sell a description as an explanation.

See Feynman speak about when he asked his father the same question:

I would love to have met Melville Feynman.

“this tendency is called intertia, but nobody know why its true. Now that’s a deep understanding. He doesn’t give me a name. He knew the difference between knowing the name of something, and knowing something.”

Similarly, Planks constant is the name of a number used in a pattern that describes of quantum phenomena. It isn’t the reason it happens on a small scale. The answer to that question is nobody knows.


Agency and Desires

“Nature doesn’t like to be in high energy states… it wants to cascade down into the lowest energy configuration that it can.”

Cox at 28:04

My issue is with the word ‘like’. This lazy speech personifies the cosmos and gives it desires. A common mistake that misrepresents physics, making it barely distinguishable from the religions and superstitions it surpasses.


Logic and Imagination

When describing the Double Slit Experiment he says, ‘it wouldn’t be logical’ to cosider only two paths.

It perhaps wouldn’t be imaginative, but I don’t see what logic has to do with it. Logic has no part to play in the creation of new theories.


Quantum Behaviour

Much of Cox’s lecture has been far better presented by Richard Feynman when he gave lectures at CALTEC in the early 1960.

Here is the transcript and audio of Feynman’s lecture on the Double Slit Experiment:

Feynman Lectures on Physics – Volume 3 Chapter 01 – Quantum Behavior

Also, Cox attempts to include Quantum Electrodynamics into the mix as well. Considering the same material took Richard Feynman (the originator of the ideas) four 90 minute lectures, that he later wrote up in a book, it is questionable what Cox hopes to achieve in 4 minutes.


Pauli’s Exclusion Principle

A lot of confusion has been generated by Cox’s remarks about this difficult aspect of quantum physics:

“When I heat this diamond up, all the electrons in the universe instantly, but imperceptibly, change their energy levels. So everything is connected to everything else.”

There has been a little talk on physics forums about this (herehere, here and here), and one reply claims to be Brian Cox himself:

The link the post cites is from Cox’s co-author Jeff Forshaw (or, if some of the University of Manchester rumors are to believed, we should say ghost-writer).

Forshaw does a better job in his article on his Manchester University web-space (available here), but it is a very technical and subtle point to make.

The assertion is true, but is practically untestable – and only occurs in the 50th significant figure of any attempted measurement. Yet another disconnected obscure idea, this time likely to encourage the new-age mysticism he was hoping to avoid.


Double Slit Experiment

About the experiment, Cox states that: ‘There’s one historic experiment which contains everything you need to know about the bizarre way that particle behave.’ He later claims it was performed in the 1920s.

However, in the form Cox presents it (firing one electron at at time), the experiment was not actually performed until 1976 by Merli, Missiroli, and Pozzi. And it was only since the 60s that it had been used as a thought experiment - an untested consequence of some accepted theory – used for educational illumination.


In his attempted explanation of the double slit experiment he says:

“[Richard Feynman] says this: … [the electron] needs to be able to interfer with itself… so it must at least go through the other slit at well and get to that point. And thee must be some mechanism for these paths interfeering with each other.”

There are several mistakes here.

Firstly, his use of ‘machinery’ is confusing. One of the key ideas to grasp the difference between quantum theory and classical physics is that there is no internal mechanical cause to explain what happens. We have rules that describe what happens over many observations, and the expected probabilities. But there isn’t a theory that provides any clockwork inside electrons that explains what’s going on.

In Feynman lecture on the same material, he says: ‘One might still like to ask “How does it work? What is the machinary behind the law?” No one has found any machinary behind the law.’ (p 10 of the above document)

Also, Feynman didn’t say that the electron travels through two slits, as Cox claims. He in fact said we are unable to know what it does.

We calculate the probabilities as though the electron traversed every permissible path, but this is a very different thing from claiming it does go through every path.

This is essential to understanding the Heisenberg Uncertainty Principle. Feynman puts it like this:

“In our experiment, we find it is impossible to arrange the light in such a way that one can tell which hole the electron went through, and at the same time not disturb the pattern. It was suggested by Heisenberg that the then new laws of nature could only be consistent if there were some basic limitation on our experimental capabilities not previously recognized. He proposed, as a general principle, his uncertainty principle, which we can state in terms of our experiment as follows: “It is impossible to design an apparatus to determine which hole the electron passes through, that will not at the same time disturb the electrons enough to destroy the interference pattern.” If an apparatus is capable of determining which hole the electron goes through, it cannot be so delicate that it does not disturb the pattern in an essential way. No one has ever found (or ever thought of) a way around the uncertainty principle. So we must assume it describes a basic characteristic of nature.”


“But, when one does not try to tell which way the electron goes, when there is nothing in the experiment to disturb the electrons, then one may not say that an electron goes through either hole 1 or hole 2. If one does say that, and starts to make any deductions from the statement, he will make an error in the analysis. This is the logical tightrope on which we must walk if we wish to describe nature successfully.”

(p 9 of the above document)


Cox also speaks of ’waves’ as though they are objects rather than oscillations of the water. He says ’For now, all we need to remember is that electrons behave like waves.’

But, as Feynman makes clear in his lecture, electrons always arrive at a detector as particle – ‘in lumps’. The way they accumulate on a screen appears to exhibit wave like properties.

Feynman puts it best in the opening remarks of his lecture:

“Things on a small scale behave like nothing that you have any direct experience about. They do not behave like wave, they do not behave like particles, they do not behave like clouds, or billiard balls, or weights or spring, or like anything you have ever seen.”

(p 1 of the above document)