Sunday, June 22, 2014

Book review: “The Island of Knowledge” by Marcelo Gleiser

The Island of Knowledge: The Limits of Science and the Search for Meaning
By Marcelo Gleiser
Basic Books (June 3, 2014)

In May 2010, I attended a workshop at Perimeter Institute on “The Laws of Nature: Their Nature and Knowability,” one of the rare events that successfully mixed physicists with philosophers. My main recollection of this workshop is spending half of it being sick in the women’s restroom, which probably had less to do with the philosophers and more with me being 4 weeks pregnant. Good thing that I’m writing a blog to remind me what else happened at this workshop, for example Marcelo Gleiser’s talk “What can we know of the world?” about which I wrote back then. Audio and Video here.

The theme of Gleiser’s 2010 talk – the growth of human knowledge through scientific inquiry and the limits of that growth – are content of his most recent book “The Island of Knowledge”. He acknowledges having had the idea for this book at the 2010 PI workshop, and I can see why. Back then my thought about Gleiser’s talk was that it was all rather obvious, so obvious I wasn’t sure why he was invited to give a talk to begin with. Also, why was I not invited to give a talk, mumble grumble grr, bathroom break.

Surprisingly though, many people in attendance had arguments to pick with Gleiser following his elaborations. That gave me something to think; apparently even practicing scientists don’t all agree on the purpose of scientific inquiry, certainly not philosophers, and the question what we do science for, and what we can ultimately expect to know, make a good topic for a popular-science book.

Gleiser’s point of view about science is pragmatic and process oriented, and I agree with pretty much everything in his book, so I am clearly biased to like it. Science is a way to construct models about the world and to describe our observations. In that process, we collect knowledge about Nature but this knowledge is necessarily limited. It is limited by the precision to which we can measure, and quite possibly limited also by the laws of nature themselves because they may fundamentally prevent us from expanding our knowledge.

The limits that Gleiser discusses in “The Island of Knowledge” are the limits set by the speed of light, by quantum uncertainty, Godel’s incompleteness theorems, and the finite capacity of the human brain that ultimately limits what we can possibly understand. Expanding on these topics, Gleiser guides the reader through the historical development of the scientific method, the mathematical description of nature, cosmology, relativity and quantum mechanics. He makes detours through alchemy and chemistry and ends with his thoughts on artificial intelligence and the possibility that we live in a computer simulation. Along the way, he discusses the multiverse and the quest for a theory of everything (the latter apparently topic of this previous book “A Tear at the Edge of Creation” which I haven’t read).

Since we can never know what we don’t know, we will never know whether our models are indeed complete and as good as can be, which is why the term “Theory of Everything”, when taken literally, is unscientific in itself. We can never know whether a theory is indeed a theory of everything. Gleiser is skeptic of the merits of the multiverse, which “stretch[es] the notion of testability in physics to the breaking point” and which “strictly speaking is untestable” though he explains how certain aspects of the multiverse (bubble collisions, see my recent post on this) may result in observable consequences.

Gleiser on the one hand is very much the pragmatic and practical scientist, but he does not discard philosophy as useless either, rather he argues that scientists have to be more careful about the philosophical implications of their arguments:
“[A]s our understanding of the cosmos has advanced during the twentieth century and into the twenty-first, scientists – at least those with cosmological and foundational interests – have been forced to confront questions of metaphysical importance that threaten to compromise the well-fortified wall between science and philosophy. Unfortunately, this crossover has been done for the most part with carelessness and conceptual impunity, leading to much confusion and misapprehension.”

Unfortunately, Gleiser isn’t always very careful himself. While he first argues that there’s no such thing as scientific truth because “The word “true” doesn’t have much meaning if we can’t ever know what is,” he later uses expressions like “the laws of Nature aim at universality, at uncovering behaviors that are true”. And his take on Platonism seems somewhat superficial. Most readers will probably agree that “mathematics is always an approximation to reality and never reality as it is” and that Platonism is “a romantic belief system that has little to do with reality”. Alas we do not actually know that this is true. There is nothing in our observations that would contradict such an interpretation, and for all I know we can never know whether it’s true or not, so I leave it to Tegmark to waste his time on this.

Gleiser writes very well. He introduces the necessary concepts along the way, and is remarkably accurate while using a minimum of technical details. Some anecdotes from his own research and personal life are nicely integrated with the narrative and he has a knack for lyrical imagery which he uses sparsely but well timed to make his points.

The book reads much better than John Barrows 1999 book “Impossibility: The Limits of Science and the Science of Limits” which took on a similar theme. Barrow’s book is more complete in that it also covers economical and biological limits, and more of what scientists presently believe is impossible and why, for example timetravel, complexity and the possible future developments of science which Gleiser doesn’t touch upon. But Barrow’s book also suffers from being stuffed with all these topics. Gleiser’s book aims less at being complete, he clearly leaves out many aspects of “The Limits of science and the Search for Meaning” as the book subtitle promises, but in his selectiveness Gleiser gets across his points much better. Along the way, the reader learns quite a bit about cosmology, relativity and quantum mechanics, prior knowledge not required.

I would recommend this book to anybody who wants to know where the current boundaries of the “Island of Knowledge” are, seen from the shore of theoretical physics.

[Disclaimer: Free review copy]


Boris Borcic said...

Do these works only address limits to aggregate human knowledge? I mean, they can be viewed as addressing (and denying) an anterior, scientist intuition that the scientific endeavor is on the track to bringing mankind to the state of omniscience previously earmarked for the Supreme Being, but the rejection of omniscience as a possibility, invites to reconsider not only our expectations for our aggregate knowledge but also the privileged status of such a conceived sum, as a precursor and best approximation to illusory omniscience. Therefore it would be natural for such works to not only discuss limits to ultimate aggregate knowledge but also acknowledge a recovered viability to a framework that treats partial states of approximate knowledge more symmetrically - and not only their (IMO fictitiously determinate anyway) aggregate at time t.

Giotis said...

Why are you intimately and exclusively coupling scientific knowledge with measurements?
Humans are not monkeys; based on existing knowledge they can acquire new scientific knowledge via the rules of logic and reasoning.

Uncle Al said...

How many Severely and Profoundly Gifted do we discard because diversity, privileged minorities, and Equal Opportunity instead mine diamonds in limestone? (Only 5 parts-per-million by weight less diamond content than in kimberlite or lamproite.)

"the purpose of scientific inquiry" Grant funding, tenure, notariety; having fun. HR educates us that "fun" is betrayal of professional trajectory. Industrial science is making your discoveries early so you can be dismissed, then engineering gives Sales and Marketing something to pimp. Pimps get commission.
" the speed of light, by quantum uncertainty,"

"Godel’s incompleteness theorems," Do opposite shoes vacuum free fall identically? "and the finite capacity of the human brain that ultimately limits what we can possibly understand." Idiot-savants. Retain a collection of specialized brains or gene-gineer fuel-blown dragsters.
"possibility that we live in a computer simulation" "Listen to me, Copper-top..." If we do, it's Windows CE.

Mats Bergenhov said...

I think monism is the Theory of Everything.

1. Pluralism means locality and separability, monism does not.

2. Entanglement can only be explained by a monistic interpretation (no need for superluminal connections).

hush said...

A king has a crown.
Most befitting to his title.

A crown most befitting to scientists bestows the title of philosophy upon them.

You are all philosophers. Your crown, your title bestows... enshrines you with this.

Don't go schizo on me. Just accept you are both simultaneously.

Just pretend you in superposition - neither scientist nor philosopher until someone probes (perturbs?) you with a measurement (question).

You are a part of Nature.
You have no choice.
That is the philosopher part of you, you hate most.

Neil Bates said...

Yes, Gleiser is a good thinker and I mostly concur. My blog had a post on him a few years ago, when he was a guest poster here:
Marcelo Gleiser Has a Point.

BTW I need to answer Allen's challenge about measure problems with infinite sets and probability. I have some ideas, will put them up in awhile.

Paul said...


Quite right - we're apes, not monkeys.

L. Edgar Otto said...

I recall not having a good feeling about John Barrows, book

Giotis, there are perfectly good reasons in philosophy to ground some idea of measurement (teleology) and there are good mathematical reasons especially if calculus applies to much of the physical world...but this is limited in philosophy as much as science - or in a sense both can be unlimited. It is deeper than ideas of quantum superposition and of free will or determinism (or for that matter imagining what happens with bubbles in some idea of inflation as proof direct or indirect for it as observable) The idea of one or many universes at the foundations is paradoxically the same thing. Boris, would you impose a number on God- would you imagine our created state beyond such touch as perhaps a necessary vanishing directly in the best of designs?)
Uncle Al, what a delightful metaphor...Leibniz and the discernible indescribable. Socks and shoes...perhaps in one case there is a difference in the falling of such complex objects and in the other a balance of symmetry.
Riemann had a lot to say about things including number theory and that in a metric at the bottom things can appear discrete.
Now, anyone know about Henri Lesbegue work with the calculus? Measure enters integration horizontal to the y axis that sets irrational and rational numbers as values of 1 or 0 all with perfectly good ideas defining limits.
I will not ask the monkeys who do not know this to raise their tails.
Neil, good comment.
Now if we add the logic called abduction which involves a sort of product of deduction and induction we do see top down or bottom up may say the same thing if the world is some Bell entanglement and as practical science nothing else. Science is the careful sorting out of these things where it can be useful and not reach too far beyond its scope.
This author sounds sensible.
Now we can image bubble universes intersecting and maybe have direct or indirect results but to build on it a proof for inflation is well, for now a little speculative.
Just saying...

Phillip Helbig said...

book “A Tear at the Edge of Creation”.

Riss oder Träne?

Sabine Hossenfelder said...


Sorry, I don't understand your question. I use the word 'measurement' as to mean a quantified observation. You can't acquire knowledge about the real world by logic alone. You can acquire mathematical knowledge by logic alone, but when it comes to the real world logic is only as good as the assumptions and you never know they are complete until you make a measurement. What logic provides is a way to arrive at a good hypothesis. Best,


Sabine Hossenfelder said...


I don't know, haven't read the book. Since the title passed the editor, I suppose it's a deliberate play on words.

Giotis said...

What about black holes or Gravitational waves? They are not part of the scientific knowledge because they have not been observed yet?

Similarly what about Hawking radiation? It is not part of the scientific knowledge?

Have we made any "quantified observations" ofHawking radiation?

Sabine Hossenfelder said...

Giotis: We have evidence for the black hole horizon. We have indirect evidence for gravitational waves. General Relativity works extremely well as a model for our present observations - that's the knowledge we have.

Giotis said...

I'm not aware of any evidence of Hawking radiation.

But assume for a moment that we had no evidence for any of these.

Would you consider them (their existence)part of the scientific knowledge?

Sabine Hossenfelder said...

Giotis: No, I do not consider the existence of Hawking radiation part of the scientific knowledge. I agree that the argument it should exist is very convincing, but since we have neither direct nor indirect evidence for Hawking radiation, its existence a hypothesis, not a fact.

Giotis said...

Then if somebody asks you whether BHs radiate. What would be your response?

Yes, no or we don't know with certainty?

Sabine Hossenfelder said...

"We expect that black holes radiate," "According to our present theories, black holes must radiate." "Almost every physicist believes black holes radiate," etc. Any of these expressions I would consider correct. Now whether I always express myself that carefully is another question...

Giotis said...

Yet we don't consider them part of the scientific knowledge.

Can't you see the contradiction?

Plato Hagel said...

In a matter dominated world there is only measurement:)

Sabine Hossenfelder said...


"Gravitational waves" is not knowledge, if that's what you mean. I would argue that "X exists" generally doesn't count as scientific knowledge because I don't know what "exists" means. Scientific knowledge that we have is for example GR describes very well the energy loss in binary systems by assuming they emit gravitational waves. Knowledge is always about observations. It is common to say "we know X exists" instead of a more careful phrasing, but scientists shouldn't confuse one with the other. We make models of nature. We don't show what is fundamentally true unless we're leading a mathematical proof.



Giotis said...

What is the definition of the term 'scientific knowledge'?

hush said...

A source of consistency is verification. Directly proportional.

Just the opposite of 'mathematical knowledge' -

(A source of verification is consistency. No proportionality here)

Works for me.

pete said...

Might have to check this out, but I'll agree that Marcelo shouldn't be nearly as definitive in his rejection of mathematical realism, which actually seems very plausible to me (and the vast majority of mathematicians and many physicists/philosophers).

This guy needs to stop equating physicalism with naturalism. Abstract relations start to look a whole lot better when you realize that atoms are 99.9999% empty space and the particles that make up that minute "physical" volume are composed of point particles according to our best theories (as in literal mathematical points, with no substructure). Marcelo might need to examine his own position a bit further before declaring "physical" things are all there is.

pete said...
This comment has been removed by the author.
Ricardo Matos said...

The search for truth doesn’t involve “believing”. Many physicists believe in the consistency of mathematics, most mathematicians believe in the certainty of logic, and almost all logicians believe that the most you can do is construct models and hope for the best. :)

Navneeth said...

Since we can never know what we don’t know...

I think that could have been phrased better.

Otherwise, it was a helpful review. Thanks.

N said...

Puchased the book after reading your review (which has so far never failed me).
But I wonder.
On the one hand the author is kindly informing us that the speed of light is denoted by "c" and even gives us the value in miles/sec.
Then he matter-of-factly jumps to dark matter, dark energy and the Higgs field.
Who the hell is the target group!?
Not that I didn't like the book, it presents a nice reading.
Not that I found in it anything that I had not read before, somewhere, too.
The conclusion is "what we think we know may or may not be true, especially when we don't know what "true" means".
Not that this is not something I did not strongly suspect for some extended period of time already.

Don Foster said...

"… what we think we know may or may not be true, especially when we don't know what "true" means".

I could not find where this quotation came from, but wonder if it is “true”.

If you mention “truth,” there are people eager to shoulder their heavy bags and go out for another long round of golf played without the holes. The finer points of that game escape me, but surely in physics the game of golf is required to have holes and the ball goes in the cup or not.

And, on the work-a-day, corporeal level there is apparently a simple and sufficient truth in the nature of things. They go this way or that way, the key fits or it doesn’t, we appropriately choose the tweezers or the pliers and strangely, reality does not require our rationale.

At least that is our mythos. And are we not buoyed up and pressed upon from every side by truth? Could we exist in a universe less scrupulously truthful, one that spoke falsely on a whim? I don’t actually know the answer, but it seems that the rare bit of falsehood in an overwhelmingly truthful universe must be the product of our cognition, the misapprehension and incongruence of our theories as to what is real. And more than human nature, this is a general property of life itself, the test of its fittingness (its truth), and its buoyancy in an impartial sea of truth.

As to the title, “The Island of Knowledge,” perhaps the “Archipelago of Knowledge” would have been a better metaphor, or even the “Galaxy of Knowledge.” Our knowledge is not of a piece, even physics is famously divided in its fundamental understanding. There is no single point of landing from which one can functionally access the whole of human knowledge.