The Power of Principles: Physics Revealed
A conversation with Nima Arkani-Hamed

How do we discover the laws of nature? We've all heard of the “scientific method” and the time-honoured convergence of theory with experiment. But how can we push our understanding well beyond where experiments can currently reach? Can theorists then simply make up whatever they please?



About Nima Arkani-Hamed:

Nima Arkani-Hamed is a Faculty Member in the School of Natural Sciences at the Institute for Advanced Study in Princeton, New Jersey.

Notwithstanding his distate for the phrase (see page 2 of "The Conversation" in the eBook), Nima is unquestionably one of the leading particle physicists of h...


Some Additional Resources:
Dreams of a Final Theory: The Scientist's Search for the Ultimate Laws of Nature

By Steven Weinberg

The Nobel Prize-winning physicist and bestselling author of The First Three Minutes describes the grand quest for a unifying theory of nature--one that can explain events as disparate as the cohesion inside the atom and the gravitational tug between the sun and Earth.

The Character of Physical Law (Messenger Lectures, 1964)

By Richard Feynman

In these Messenger Lectures, originally delivered at Cornell University and recorded for television by the BBC, Richard Feynman offers an overview of selected physical laws and gathers their common features into one broad principle of invariance. He maintains at the outset that the importance of a physical law is not "how clever we are to have found it out, but... how clever nature is to pay attention to it," and tends his discussions toward a final exposition of the elegance and simplicity of all scientific laws.

The First Three Minutes: A Modern View Of The Origin Of The Universe

By Steven Weinberg

This classic of contemporary science writing by a Nobel Prize-winning physicist explains to general readers what happened when the universe began, and how we know.

2010 Messenger Lectures - Cornell University

By Nima Arkani-Hamed

A series of 5 lectures delivered at Cornell University. Video streaming available on Nima's personal webpage (scroll down to the list of five links).

1. Setting the Stage:Space-Time and Quantum Mechanics
2. Our "Standard Models" of Particle Physics and Cosmology, and their Discontents
3. Space-Time is Doomed: What Replaces It?
4. Why Is There a Macroscopic Universe?
5. A New Golden Age of Experiments: What We Might Know By 2020?

Beyond Nymphs, Dryads and Leprechauns (Commentary Excerpt)

How does science work?

Well, that’s easy, right? We start off by collecting information about the world around us and then we try to make some sense of it: we look for patterns, search for a more general understanding.

In time, we develop sufficient awareness of these patterns that we begin making predictions about what else might be out there – explicitly formulating hypotheses of what we would expect to see under specific, controlled scenarios. Then we go ahead and rigorously test our hypotheses by explicitly creating these particular conditions; coolly assessing whether or not what has been predicted does, in fact, occur.

If it doesn’t, or at least doesn’t with any sense of regularity or precisely in the way that we had envisioned, we’ll be forced to accept that at least one of our original hypotheses was incorrect and head back to the drawing board to modify things in an attempt to develop a more accurate level of understanding.

Meanwhile, if all of our predictions do come true, then we’ll find ourselves with increasing confidence in our understanding. At some point, we’ll likely start calling it something more grandiose, like a 'theory'; and if it keeps working like clockwork for everything in its applicable domain that we can imagine, we will eventually be tempted to call it a 'law'.

Such is, in a nutshell, what most of us mean by “the scientific method”. It is famously objective, logical and eminently reliable; and the fruits of its success, both pure and applied, are the single most obvious factor in distinguishing the varying levels of progress between different human societies throughout history.

But what happens when the experimental arena becomes less and less accessible? In the world of high-energy physics, where hugely expensive laboratory facilities take decades to construct, what can we do in the meantime towards uncovering nature’s secrets? And how might we even conceivably make progress and build upon our knowledge when no further experiments are in sight?

Can we just sit back and invent any hypothesis we want, secure in the knowledge that, far away from any experimental arbiter, there is no way of distinguishing, even in principle, between different theoretical possibilities? Does science at this point simply become science fiction?

To Nima Arkani-Hamed, faculty member of the prestigious Institute for Advanced Study and one of the world’s foremost theoretical particle physicists, that sort of talk is not only wrong, it demonstrates a profound misunderstanding of all that fundamental physics has accomplished since Galileo brought us into the modern era more than four centuries ago.

Arkani-Hamed emphasizes that our understanding of the physical world is based on two phenomenally successful general principles of 20th century physics, relativity and quantum mechanics, which, when put together: “almost completely dictate what the world around us can possibly look like”.

“You could easily imagine a world without relativity and you could easily imagine a world without quantum mechanics. Either way things would be tremendously less constrained. It’s the existence of both of them that makes things so complicated.

"In fact, if I were God and I was given principles - or a sub-God, given the principles of relativity and quantum mechanics by the actual God who told me, ‘Now go, build a world,’ I’d say, ‘Sorry, can’t do it. This is just impossible.’ They seem almost completely incompatible with each other”.

For the full Commentary, purchase this issue from our site, or buy the eBook from or iBookstore, or download our app off Apple Newsstand. Each issue comes with the commentary, the full conversation, a biography of our guest, as well as references for further exploration.