feynman

Just so you know, nobody knows what energy is

The following acts as my introduction to the students’ notes on the Energy chapter.

What is energy?

Nobody knows what energy actually is and by pretending otherwise we actually do you the student a disservice. Not only are we ignoring the wonder associated with the idea, we are also denying you the opportunity to engage with the concept at any level beyond the superficial.

Bottom line; nobody gets energy because there’s nothing to get. Energy is not tangible (it is ‘an indirectly observed quantity’); you can’t hold it in your hand, you can’t weigh it on an electronic balance, you can’t see it, touch it, smell it etc. Yet when the universe was first created there was a certain amount of this put in to the mix (actually now that I think about it the mix itself was energy (with perhaps just a little dash of time)), and it’s all still there today. Its form can change, but the energy itself can’t ever disappear – no sirree bob.

It could be argued that it is in fact merely an accountant’s trick which enables him to ensure that all actions balance.

Consider the following analogy which I like to use.

If a child asks you ‘what is money?’ you could take a few coins out of your pocket and show them to the child and say ‘this in money’. Now fast forward a couple of decades; all transactions are now done electronically/online and all coins and paper money are no longer legal tender. Now how do you explain what money is?

Well it’s a means of payment for goods and services, right? Somebody sells you an orange and you agree to transfer into their account a set amount of this ‘money’. And now that the shopkeeper has this money in his account he can use it to buy something else. So in effect money is just a transferrable IOU.

Now energy is a bit like this, but there is only a certain amount of IOU’s in the universe and this was set when the universe first came into being.

To complicate matters further, since the early part of the last century we now know (thank you Albert) that all matter (‘stuff’) is basically energy in another form.

Anyone still with me?

 

All right, let’s listen to Richard Feynman give his take on it.

There is a fact, or if you wish, a law governing all natural phenomena that are known to date. There is no known exception to this law – it is exact so far as we know. The law is called the conservation of energy. It states that there is a certain quantity, which we call “energy,” that does not change in the manifold changes that nature undergoes. That is a most abstract idea, because it is a mathematical principle; it says there is a numerical quantity which does not change when something happens . . . it is a strange fact that when we calculate some number and when we finish watching nature go through her tricks and calculate the number again, it is the same. It is important to realize that in physics today, we have no knowledge of what energy “is.” We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. It . . . does not tell us the mechanism or the reason for the various formulas.

The Feynman Lectures on Physics Vol I, p 4-1

When Feynman wrote,
“It is important to realize that in physics today, we have no knowledge of what energy is,” he was recognizing that although we have expressions for various forms of energy (kinetic, heat, electrical, light, sound etc) we seem to have no idea of what the all-encompassing notion of “energy” is.

The various forms of energy (½mv2, mgh, ½kx2, qV,mcT, ½I2, ½CV2, etc.) are abstractions not directly observable.

2007 American Association of Physics Teachers

Now with that interesting bit out of the way, let’s go see what we need to know for the exam.

coe

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Wonder in Science (why do we hide it?)

Yes, yes, yes, yes!

Just read this online article from Simon Jenkins in the Guardian

I devour popular science, finding its history and its wonder a constant delight. . . . It is a mystery how so many science teachers can be so bad at their jobs that most children of my acquaintance cannot wait to get shot of the subject. I am tempted to conclude that maths and science teachers want only clones of themselves, like monks in a Roman Catholic seminary.

I couldn’t agree more. It is a sense of wonder in the world around me that has drawn me into science, and yet wonder is the one thing that is sorely lacking from all text-books and school syllabii. And we as teachers are doing absolutely nothing about it. We should be ashamed of ourselves.

Listen to all the big-wigs tell us why we need more students doing science – it’s the economy, stupid. Yet ask any kid why they are fascinated with science and the economy is not likely to come top of their list of reasons. It’s that word again – wonder. So why are we afraid to tackle it at school level? And why does nobody talk about it?

Heaven preserve us from engineers, university professors and politicians getting their grubby mitts on another science syllabus. Not unless they can first demonstrate a proven track recond on rating wonder as highly as a kid does. Not that we teachers have much to boast about in that regard either. It’s as though we try to hide our sense of wonder because somehow it doesn’t seem appropriate. Is it because we teachers like to give the impression that we have all the answers and therefore there should be nothing to fill us with wonder. I honestly don’t know. And I’m not even sure what I can do about it.

But I guess a good aul’ rant wouldn’t be a bad place to start. 

Feynman, in this regard as in so many others, remains an inspiration.

Neutrinos, John Updike and Cosmic Gall

I’m suspect it may not have been part of his overall plan, but the death of John Updike coincided (can I say ‘nicely’?) with our class on Neutrinos.

There are some strange particles out there, but not many as strange as the neutrino.
Here’s what the syllabus has to say on neutrinos:

If momentum is not conserved, a third particle (neutrino) must be present.

And that’s it.
Here’s what Updike has to say.
This is why scientists need poetry.

Cosmic Gall

NEUTRINOS, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids down a drafty hall
Or photons through a sheet of glass.
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold shoulder steel and sounding brass,
Insult the stallion in his stall,
And scorning barriers of class,
Infiltrate you and me! Like tall
and painless guillotines, they fall
Down through our heads into the grass.
At night, they enter at Nepal
and pierce the lover and his lass
From underneath the bed-you call
It wonderful; I call it crass.

Telephone Poles and Other Poems, John Updike, Knopf, 1960

What a wonderful counter to the claim that Science leads to a loss of wonder due to over-analysis (now replace ‘Science’ with ‘Science Education’ and that’s a different matter.)

Updike is referring to the fact that are about 50 trillion of these buggers passing through us every second! (rounded off to the nearest whole number, obviously).
I need to say more about these guys in a later post; their origins are just as amazing. Maybe I could use a podcast to try and get across the emotion that should be part and parcel of discussing neutrinos.

Anyway I say put that poem on the syllabus. And for the exam itself one word would suffice: “Discuss”.