Susskind & Steinhardt: The Universal Laws of Physics?

Are the laws of physics universal? That is to ask: Do the laws of physics apply throughout entire universe?

If the laws of physics aren't universal, then wouldn't that have a profound affect not only on physics itself, but also on the pursuit of physics? This is a fairly recent worry for many physicists and cosmologists.

It can now be asked if physicists need their laws to be universal. Yes they do, some may say, in order for there to be laws of physics at all! Others may say that universal laws are required in order to make things simpler (to put it simply). However, can't there be laws of nature which change over time and which don't apply throughout the universe?

The universe itself is... well, universal; though why should the laws of physics also be universal? Of course it can (semantically) be said that the words “law of physics” have the notion of universality built into them. However, isn't that simply a contingent semantic fact (possibly) without any profound or necessary implications?

Despite stating all the above, many definitions of the laws of physics don't even mention their universality.

Take this definition:

“The laws of science, scientific laws, or scientific principles are statements that describe or predict a range of phenomena as they appear in nature.”

And this one:

“Scientific laws summarize and explain a large collection of facts determined by experiment, and are tested based on their ability to predict the results of future experiments.”

Then again, some definitions of the laws of physics do indeed mention their universality. For example:

“Physical laws are Universal. They appear to apply everywhere in the universe....Everything in the universe apparently must comply with them (according to observations).”

In terms specifically of the physical constants (or the “constants of nature”), there's also this definition:

“A physical constant, sometimes fundamental physical constant, is a physical quantity that is generally believed to be both universal in nature and have constant value in time.”

Susskind on Universal Laws

If the laws of physics aren't universal, then what are they?

Let the American physicist Leonard Susskind explain one possibility:

“If these things prove true, then some features of the laws of physics (maybe most) will be local environmental facts rather than written-in-stone laws – laws that could not be otherwise.”

Despite Susskind's words, physical laws were always meant (historically, philosophically and scientifically) to be universal. That is, all the laws of physics were meant to be instantiated in all cases – whether in all similar experiments, similar conditions, when it came to all planets/stars, etc. Thus some people (in response) may say:

How can there be laws at all if they aren't universal?

National political laws, on the other hand, are (to use Susskind's word) “local”. And there are no “genuine laws” in the philosophy of mind or economics either. That's because there are no mental or economic phenomena which are exceptionless. Another way to put that is to say that various “ceteris paribus clauses” are always shoehorned into “mental laws” or the laws of economics in order to make these laws come out as laws. Yet some scientists and philosophers have also said the same about the laws of physics! (See Nancy Cartwright's How the Laws of Physics Lie.)

So if the laws of nature are of ultimate importance in physics (and those laws are supposed to be universal), then anything that fundamentally challenges this will cause a certain amount of consternation within the community of physicists and beyond. (As we'll see with Paul Steinhardt later.) 

Again, if we haven't got laws because we haven't got universality, then what have we got?

Leonard Susskind expresses the worry in this way:

“What... worries may physicists is that the landscape may be so rich that almost anything can be found – any combination of physical constants, particles masses, and so forth. This, they fear, would eliminate the predictive power of physics. Environmental facts are nothing more than environmental facts. They worry that if everything is possible, there will be no way to falsify the theory – or, more to the point, no way to confirm it.”

If Susskind's “landscape” were infinite, then “anything [could] be found”. If we think in terms of the philosopher David Lewis's “possible worlds”, then anything is possible at these worlds - as long as they don't involve logical contradictions, inconsistencies, etc. However, these possible worlds could/do indeed involve different laws of physics and therefore different constants of nature. Thus, as with David Armstrong, we have possible-worlds “combinatorialism” in which not only are properties and facts combined in an indefinite number of ways: so too are the constants of nature.

In terms of Susskind's landscape again: Where does that leave physicists? If laws are “local” or “environmental”, then in what sense are they laws at all? Having said that, is there anything, prima facie, to stop laws from being (merely) local?

Take this hypothetical scenario.

Physicists once knew about a universe which they said was “governed by the same physical laws”. However, it came to be seen that this wasn't actually the case. Instead that universe was really divided in four neat-and-tidy sections.

Now within each of those four sections, the laws were then deemed to be “universal” - or at least they applied (across the board) within each section.

Now what's to stop there being (genuine) laws for each of these four sections of a previously (seemingly) homogeneous large section of spacetime? After all, each section still as its own laws which apply within it.

There is a problem: What's to stop this process continuing?

That is, perhaps each of these four sections (of a once-larger section) were itself be broken up into another four sections (now totaling 16 sections). In principle, this could happen! Indeed this could occur ad infinitum. Though it can also be said that it wouldn't necessarily happen. It just possibly could happen.

So how does this thought experiment compare to what we actually know about our universe in 2019? In terms of any possible sub-spatiotemporal sections of our own known universe, does this scenario so much as make sense?

Susskind: Laws Enable Predictions

Leonard Susskind also ties the laws of nature to what he calls “the predictive power of physics”. In other words, laws are mainly required for reasons of prediction. So if the laws we uphold aren't universal, then wouldn't prediction prove to be more difficult or even impossible? In other words, if laws don't apply across the board, then how are predictions possible?

Perhaps physical laws are still applicable even in our previous hypothetical subsections of the universe. Therefore perhaps such laws may - or will - still do their job in these hypothetical sections.

So what about predictions about the parts of the universe we've never observed? What about those parts we have limited information about? Again, most physicists want both their laws and predictions to be universal. If this weren't the case, then some physicists may say: What's the point? Well, there are lots of sciences which don't deal with universal or exceptionless laws; such as economics, sociology, psychology and the like. However, these disciplines are “soft sciences”. Physics is a “hard science”.

Would the truth of these speculations mean that all the sciences (including physics) are actually soft – at least in relative terms?

Paul Steinhardt: Physical Modality

Let's ask the earlier question again: Are the laws of physics universal?

The Albert Einstein Professor of Science at Princeton University, Paul Steinhardt, asks us a simple question (hinted at earlier) which relates our own questions:

“What is the point of exploring further the randomly chosen physical properties in our tiny corner of the multiverse if most of the multiverse is so different?”

There are wording problems with much of what Paul Steinhardt says above. Nonetheless, that may depend on how literally Steinhardt wants his words to be taken.

For a start, what does the word “randomly” mean in the phrase “randomly chosen physical properties”? If those physical properties weren't randomly chosen, then what would the alternative/s be? That these physical properties are necessary? That God chose them? That God chose them and He did so necessarily?

Why use the word “chosen”? Even if the physical properties weren't random, why did they also need to be chosen? And even if they were chosen, then surely they could still be random in the sense that the Chooser might well have chosen different physical properties. (Or the Chooser might have chosen different laws to underpin these physical properties.)

Again, what do the words “necessary properties” or “necessarily chosen properties” so much as mean?

Are the Laws of Physics Necessary or Contingent?

If someone says

The laws of physics (or nature) are necessary for x.

what is he/she saying? That the laws of physics couldn't have been any other way? Possibly. 

The universe wouldn't be the way it is today (as well as life wouldn't be the way it is today - or even have come about) if the laws of nature hadn't been the way they were at the beginning of the universe and beyond. However, that doesn't make the laws themselves necessary. The necessary relation here is one between the laws of physics and the nature of the universe as it is today.

So what about making a claim about the necessity of the laws being the way they are (or were) in the first place? Why is it necessary for them to be the way they are (or were)? True, if they had been different, then we wouldn't be here today. However, that's not the question. The question is:

Why is it necessary that the laws were/are the way they were/are?

It can be said that it was necessary that they were the way they were in order to bring about the universe we know today. Here again, this is about the (necessary) relation between the laws and the nature of the universe today or indeed at any time. It's not about the laws as they were/are in and of themselves.

All this works for the words “accidental”, “contingency” and “chance” too. Thus:

If the laws of physics are contingent (or accidental), then that only makes sense in the context of the possibility that they might/could have been necessary.

Though if they couldn't have been necessary in the first place, then perhaps they couldn't have been accidental or contingent either.

There is another option which some people make (or simply hint at). 

The physical constants necessarily have their strengths, values, etc. because God made them that way in order to bring about the universe (as well as the people) we know today. (For example, the speed of light, the gravitational constant, the Planck constant, the elementary charge of a proton or electron, etc.)

Though here again that necessity is smuggled in to explain why people are here today and also why the universe is the way it is today. That necessity doesn't (or may not) belong to the laws themselves.

Similarly, when Lawrence Krauss says that

“the laws of physics we observe are mere accidents of our circumstances, and that there could exist an infinite number of different universes with different laws of physics”

what is he actually saying?

More specifically, what function is the word “accident” fulling here? If the laws of physics weren't/aren't accidents (or accidental), then what could they be? Necessary? And if they were/are necessary, then what does that mean? Moreover, if the word “accident” has no purchase here, then neither has the word “necessary”. That's because modal logicians and philosophers often tell us that modal notions only make sense as a package-deal. In this instance, the notion of accident (or contingency) only has purchase alongside necessity; just as possibility (which itself is related to accident/contingency/chance) can only work alongside necessity.

Possible Worlds

If one is a believer in possible worlds (or, alternatively, if one believes that an acceptance of modal notions necessitates a belief in possible worlds), then one won't have a problem with the laws of physics being contingent. This is how John Earman puts it:

“Laws are contingent, i.e., they are not true in all possible worlds.”

Of course we may not need to smuggle in possible worlds in order to question the assumption that laws must either be contingent or necessary. In any case, possible worlds are - by definition (or at least David Lewis's definition) - causally, spatially and temporally cut off from us. So, from a strictly scientific perspective, they're (almost?) irrelevant.

There's also another very simple point. The possibility that physical laws may - or even will - be different at other possible worlds doesn't it stop it from being the case that the laws of physics are universal; just as it doesn't stop them from being contingent or necessary at our world. Then again, if necessity is "what is true at all worlds", and if the laws of our world are necessary, then their necessity must be replicated at all possible worlds.

Bogus Philosophical Questions: Logic and Metaphysics (3)

Philosophy of Logic

Take these well-known statements from the philosophy of logic. Namely:

(A) The sentence A is not true.

And:

What I'm now saying is false.

The logical argument here is that we can grammatically assert the sentences above and grammatically apply the predicate “is false” (or “is not true”) to them. However, doesn't that depends on what's meant by the words “we can grammatically assert the sentence”?

Now the sentence

This sentence A.

or even:

This sentence.

is surely not "grammatically acceptable". After all, the words “is not true” are predicated of the words “The sentence A” (or “The sentence”). Thus, what we're really dealing with are the words “The sentence A” (or even the two words “The sentence”).

This is roughly equivalent to saying

I walk down.

or even

This is.

and leaving the locution there. Surely no teacher of English grammar would accept this sentence on its own.

In other words, what if the logic and the paradoxes don't work if the sentence has no semantic or propositional content? Or, to put that another way, perhaps the paradoxes only arise because the sentence “(A) The sentence A is not true” has no propositional content. (Indeed wouldn't this also apply to the Liar Paradox?)

So perhaps this well-known example from logic is all down to its syntax and not its semantics. And if it's all down to syntax, then one can see why some logicians have seen the sentence as being logically acceptable. That is, it's about the form/syntax of these sentences (as well as the problems/puzzles/paradoxes they create): not their content. Though if that's true, isn't it a sleight of hand to use sentences which appear to have content?

Indeed a “non-cognitivist” position may state the following:

The Liar Paradox isn't about propositional content.

Okay, perhaps the Liar Paradox isn't about propositional content. Though what about the sentence “(A) The sentence A is not true”; which doesn't take exactly the same form as the Liar Paradox? And why isn't the Liar Paradox itself also about propositional or semantic content? Or, at the very least, why isn't content seen as being relevant at all?

So let's take another example. Say someone states the following:

I'm lying to you at this very moment in time.

Then a logician can go on to say:

No one will say that the sentence “I'm lying to you at this very moment in time” has no content.

Grammatically speaking, the sentence “I'm lying to you at this very moment in time” is a great sentence - grammatically. We all know what the individual words means and it seems to make sense. However, what is its propositional or semantic content?

The statement “I'm lying to you at this very moment in time” could have propositional or semantic content if the self-accusation of lying refers to other statements the speaker (or liar) had made previously. (Those other sentences would then be false.) However, it's supposed to be a self-referential statement. So what is this man lying about, exactly? He can't be referring to his lying alone because in order to lie, you have to make a claim that's false and also to believe that it's false. Surely the fact is that he's neither lying nor telling the truth.

Mr X is only stating a grammatically-acceptable sentence; though one which has no propositional or semantic content. Therefore he can't be lying or telling the truth.

We can now ask this question:

If the sentence “I'm lying to you at this very moment in time” has no content, then why is it still seen as still being grammatically acceptable?

Now compare

I'm lying to you at this very moment in time.

with

I'm singing to you at this very moment in time.

These two sentences aren't equivalent. And that's not simply because one is about lying and the other is about singing.

When someone says “I'm singing to you at this very moment in time” he's either lying or telling the truth. (He could be singing those words.) That doesn't work for the sentence “I'm lying to you at this very moment in time”. The sentences have the same grammatical form; though the latter is neither true nor false. The former is either true or false. And even if they have the same grammatical form, one is has a truth-value and the other doesn't. Indeed, despite what was said a moment ago, it can now be argued that it's because of this difference, the two sentences can't have the same grammatical form.

Again, because the sentences “I'm singing to you at this very moment in time” and “I'm lying to you at this very moment in time” have the same shape (or form), that creates problems. They may well have the same grammatical shape. Though one could be true or false and the other is neither true nor false. That difference seems to be clear.

Metaphysics

So what about this more philosophical question? Namely:

Why is water H₂O?

Or:

Why is the speed of light 186,000 miles per second?

As well as:

Why is the invariant mass of an electron approximately 9.109×10−³¹ kilograms?

We can also add the following question:

Why is water wet?

An answer to the last question would presumably tell us about the interaction of H₂O molecules and human skin; as well as facts about brains, central nervous systems, sensory receptors, etc. It would also involve a subjective component as to what it is like to experience something wet.

Liquidity (not wetness), on the other hand, can be explained by science and without recourse to “phenomenal feels” (or experience generally).

Thus perhaps we should ask the following question:

Why do H₂O molecules give rise to liquidity?

That question doesn't involve an experiential component.

However, let's get back to this question:

Why is water H₂O?

Isn't this question necessarily unanswerable or even meaningless?

Perhaps, it's just a brute fact that H₂O molecules giving rise to water because they equal water. In other words, this “brute fact” isn't amenable to an explanation.

We can also ask:

Why is water constituted by H₂O molecules?

Or:

Why do H₂O molecules bring about (or cause) water?

The question

Why does the brain/the physical bring about/cause consciousness?

is similar; though certainly not exactly the same. For one, if we have enough H₂O molecules, then we have water and can observe water. We can touch, taste and see water when enough H₂O molecules are brought together (or found together). We can also see H₂O molecules under and microscope.

When we observe brains, on the other hand, we can't touch, taste, or see consciousness. We can experience or our own consciousness; though only from the inside (as it were). So the H₂O-water and brain-consciousness questions are similar; though certainly not the same. Nonetheless, it can still be said that the question is bogus even if consciousness has what John Searle calls a “subjective ontology”; whereas water-H₂O clearly doesn't.

Bogus Philosophical Questions: G.P. Baker (1)

What I'll attempt to do in the following is summed up very well by the American-English philosopher Gordon Park Baker. In his 'φιλοσοφια: εικων και ειδος' (which can be found in Philosophy in Britain Today), Baker wrote:

“We should... make serious efforts at raising questions about the questions commonly viewed as being genuinely philosophical. Perhaps the proper answers to such questions are often, even if not always, further questions!”

All sorts of questions have been deemed to be profound, deep and worthy of serious thought. However, perhaps it's just as important - and indeed just as philosophical - to ask questions about these questions. Or as Gordon Baker puts it:

“The unexamined question is not worth answering.”

Baker adds:

“To accept a question as making good sense and embark on building a philosophical theory to answer it is already to make the decisive step in the whole investigation.”

At the outset, however, it must be noted that what follows isn't a defence of a position that's similar to that which was once held by Russell, Wittgenstein or by the logical positivists. Nor is it a defence of some of the positions advanced by “ordinary-language philosophers” in the 1940s, 1950s and early 1960s.

That is, it's not being argued here that many everyday - and indeed philosophical - statements have a “logical” or “philosophical grammar” which somehow hides deep underneath them. Or at least it isn't part of my argument that the logical grammar of (possibly) bogus questions is hidden.

On the other hand, neither do argue that, as the late Wittgenstein put, “nothing is hidden”.

It's also the case that I don't have a problem with poetic philosophical statements. Take this two examples from Friedrich Nietzsche (both from Beyond Good and Evil):

“I obviously do everything to be 'hard to understand' myself.”

“The text has disappeared under the interpretation.”

As they stand, these sentences aren't meant to be philosophical arguments. They're poetic and/or cultural statements. Nonetheless, philosophical arguments or positions are still embedded within them and can easily be eased out.

Ironically, Wittgenstein himself certainly did see Nietzsche as a philosopher. Indeed it can be said (it often has been said) that many of the Wittgenstein's own statements or questions are poetic, gnomic or “mystical” in nature.

In addition, there's no need to use the word “nonsense” about most (or indeed any) of the questions or statements considered in the following piece. (Despite saying that, the word 'nonsense' wasn't used – by philosophers – in its everyday sense: it usually had a precise technical or philosophical meaning/usage.) For example, saying that a particular question simply assumes that there's an answer (or that a question can't be answered at all) doesn't seem to be a point about logical grammar or about nonsense... 

There's an equivocation here because in Wittgenstein's Culture and Value (a selection from the philosopher's personal notes), he wrote the following:

"As long as there continues to be a verb 'to be' that looks as if it functions in the same way as 'to eat' ... people will keep stumbling over the same puzzling difficulties.”

Now who can have a problem with that? That position may not be entirely acceptable (as it stands); or it may simply be partial. However, if the question

“What is it like to be?”

is asked partly (or indirectly) because questions like

“What is it like to eat Heinz Beanz?”

are also asked, then there may well be a problem.

Bogus Philosophical Questions?

All sorts of questions can be asked. And two fundamental things are assumed when a question is asked:

i) That the question makes sense. (This use of the word 'sense' is meant in a loose non-philosophical sense.)

ii) That the question must (or does) have an answer.

In addition, another problem is summed up (again) by Gordon Baker:

“Questions, just as much as assertions, carry presuppositions.”

This is especially true in philosophy. The type of questions I primarily have in mind here are the following.

i) “Why does the physical give rise to consciousness?” (Or in David Chalmers' words: “How do physical processes give rise to experience?” )

ii) “Why are the constants of nature the way they are?” (Or: “Why do the laws of physics have the numerical values they do have?”)

Just because a question is grammatical and even makes (some kind of) sense, that doesn't mean that it's a philosophically (or otherwise) legitimate question.

So firstly let's take an extreme question:

“Why does the number 6 have such a poor sense of humour?”

Now that's a perfectly grammatical sentence. It even makes some kind of sense. (It does so – at least in part - precisely because it is grammatical.) However, in a philosophical and even commonsensical sense, it doesn't make... well, sense.

To back this up, let's use Noam Chomsky's well-known surreal sentence (though not itself a question). Namely:

“Colorless green ideas sleep furiously.”

All the words (as well as their concepts) in the question are “transparent” when taken individually. (That is, if words can ever be taken individually or outside of the “Fregean context” of a whole sentence.) More relevantly, the sentence itself is grammatically correct – and it may even be logically correct. (Chomsky said that it is “semantically nonsensical”.) However, isn't it also empirically, scientifically and even metaphysically nonsensical? (Hence Chomsky's semantic position.) Nonetheless, can't we still understand that statement?

Take these questions about Chomsky's sentence:

i) Can we conceive of that statement being true? (The word 'conceive' is often used by philosophers who make use of modal notions.)

ii) Do we need to conceive the statement's truth-conditions in order to understand the statement?

iii) Can we even conceive of a situation in which colorless green ideas sleep furiously?

Here it seems that grammatical (or even logical) correctness runs free of conceivability - not only of Chomsky's semantics. In other words, perhaps we don't - and can't - actually conceive of colorless green ideas sleeping furiously at all. Nonetheless, the sentence can still be understood simply because it's grammatical. Though all that, of course, depends on precisely what's meant by the word 'understand'!

So let's take a slightly less extreme question:

“Why does everyone simply adore Anton Webern's Symphony Op. 21?”

That question is also perfectly grammatical. And it's certainly not surreal like the first question. However, the question is somewhat bogus because it simply assumes that everyone does love Webern's Symphony Op. 21. (Of course it's possible that they do.) So this is very much like this well-known question:

“When did you stop beating your wife?”

In other words, both questions beg the question (i.e., they "assume the [or an] initial point").

So the first question is rightfully deemed to be ridiculous. And the second question begs the question.

G.P. Baker's Wittgensteinian Position

So perhaps these questions about questions are partly Wittgensteinian in nature. That is, I certainly appreciate Gordon Baker's Wittgensteinian points made in the following:

“... to suppose that the answers to philosophical questions await discovery is to presuppose that the questions themselves make sense and stand in need of answers (not already available). Why should this not be a fit subject for philosophical scrutiny?”

Indeed Wittgenstein did have things to say on the nature of many philosophical questions (both in his “early” and “late” periods). His position is partly summed up in this passage from Robert W. Angelo. (It contains a quote from Wittgenstein himself.) Thus:

“... nonsense in the form of a question is still nonsense. Which is to say that the question-sign... can only be rejected, not answered: 'What is undefined is without meaning; this is a grammatical remark.'...”

In other words, any question can be asked. And any question may be taken to be legitimate simply because it's grammatical and also because it makes a modicum of sense (i.e., though only if that last word is used very loosely). All the examples given so far may fit these categories.

So take this question:

“Why is water H₂O?”

Or what about this well-respected (i.e., by logicians and philosophers) statement? -

A: This statement [A] is false.

Another good way of summing up the problem with these possibly-bogus questions (or statements) is also cited by Gordon Baker. He writes:

“Questions, just as much as assertions, carry presuppositions. To pose a particular question is to take things for granted, to put some things beyond question or doubt, to treat some things as matters of course...”

As stated before, one obvious “presupposition” to a question is that there's an answer to it; or at least a possible answer.

Now take a seemingly silly question which was first mentioned by Bertrand Russell. (This question is sometimes used to flesh-out issues within the realism/anti-realism debate.) Here's my (very slight) paraphrase of the question:

“Is there a china teapot between the Earth and Mars which is revolving about the sun in an elliptical orbit?”

The presupposition here might have been that we - even if only in principle - could discover the truth or falsity of this statement. (Though this wasn't Russell's point.) Does that also work for Chomsky's earlier statement (i.e., “Colorless green ideas sleep furiously”)?

It's possible that we could at least attempt to find an answer to this tea-pot question. However (to state the obvious), we'd quickly find out there are no green ideas. Therefore the question as to whether or not green ideas “sleep furiously” can't (or shouldn't) even arise. In other words, what's being presupposed here is there are green ideas.

Now what's being presupposed here? -

“Why is water H₂O?”

Can the same question also be asked of this question from David Chalmers? Namely:

“Why should physical processing give rise to a rich inner life at all?”

To repeat: a (possible) answer is being presupposed in both cases. That is, the very asking of these questions means that the questioners must assume that there are answers – at least answers in principle.

To use the words of Baker again. Aren't these questioners “taking certain things for granted”? That is, aren't they primarily taking for granted that their questions are legitimate and that there are answers? Moreover, aren't these questioners also “put[ting] some things beyond question or doubt”; as well as “treat[ing] some things as matters of course”?

[All the possibly-bogus questions just mentioned will be tackled in greater detail in the later parts of this piece.]

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*) See my 'Bogus Philosophical Questions: David Chalmers & KittyFerguson (2)'