Fast note on Scientific Principles, Bell’s Inequality, Relative Simultaneity

I’ve not posted in a long time. There’s about seven draft posts still sitting there waiting to be finished. I don’t have much time since last October. I’ve a 9-6 non-academic job, and any time outside that I’ve been spending on projects with other people.

So, I’ve decided to do a few fast posts. The first one is about the physics of time. It’s a thought I have about it, involving changing my basic views of simultaneity.

At Christmas, I had two discussions with, first, a well-established very-good-at-it professional physics friend and, second, a friend who is equally a very good at it professional philosopher of physics. With both, I brought up a question about relative simultaneity and what Tim Maudlin tells me is the violation of Bell’s Inequality.

Without going into it too much–I am not a physicist and do not want to pretend that I fully understand the physics–the problem is this: One implication of quantum entanglement is that two particles created by the same event–e.g., in a lab–can have properties with values dependent on the values of the other. You can change the value of one particle’s properties by changing the value of at least one of the properties belonging to the other particle.

So, for example, one particle might have a spin of 1 and the other a spin of -1 (don’t worry what it means to have spin ‘-1′. It isn’t really spinning being discussed here).

The two particles – 1-spin and -1-spin – are created and speed away from each other into space. Say they’re now 90,000,000 miles apart. Now we change the spin of the one of the particles, e.g., the 1-spin to -1-spin. The other particle’s spin also changes.

The problem I had with this is it seems to violate relativistic physics. Not the maths as such, but the underlying interpretation.

Fundamental to relativistic physics is the principle of equivalence: the idea that the laws of physics are the same in all frames (Encyclopedia Britannica entry on the principle). Each frame is equally correct for describing physical phenomena.

Included in this equivalence are the descriptions of space and time, e.g., that two events are simultaneous. If two events are simultaneous in one frame, and not simultaneous in another frame, both are as equally correct. This is not incoherent. The events are relatively simultaneous.

This solves some problems. For example, one can discount a physical aether. It is also very like similar relative physical phenomena–for example, some objects are at rest and in motion without contradiction because they are at rest to relative to one frame and relatively in motion to another frame.

As Galison describes it, Poincaré and Lorentz came up with similar mathematical descriptions to the maths in Einstein’s relativity (see Galison’s book). The difference is that they still took there to be a matter of fact whether or not two events are really simultaneous beyond how they are described in a frame. This would make it the case that:

– There’s real simultaneity (or motion/rest) beyond frame-relative simultaneity (or motion/rest).

– There’s at least one frame–a privileged frame–which has values of simultaneity (or motion/rest) which correspond to the real simultaneity (motion/rest).

The point is that a cornerstone of Einstein’s revolutionary thinking is the abandonment of an aether and absolute motion/rest. To do it, and make sense of the experimental evidence, he also abandoned absolute simultaneity (and, as a consequence, any privileged frame).

I have a problem with this when it’s coupled with current quantum theories and the evidence that supports it–that is, experimental evidence from Aspect et al. (Aspect et al’s paper on the much-discussed experiment, discussion on the philosophy of Bell’s Theorem). After discussing it with my physicist friends, I then cold-mailed Professor Tim Maudlin. He sent me a quick, but thorough and helpful reply.

I described the problem to Maudlin as follows:

Part of the typical description of a scenario implied by [Bell’s Inequality] is the claim that, if the spin of an entangled particle is changed, then at the same time, the spin of the particle’s entangled partner also changes. As the particles are spatially separated from one another, this is a description of simultaneity between spatially separated events.

Yet, there seems to be no mention of relative simultaneity here. For example, there is no reference to some frame for the simultaneity and then, say, a further clarification that, to some other frame, the events would be non-simultaneous.

Physicists I’ve discussed it with tell me there is no problem. It is not possible for information about these states to be communicated faster than light. So the speed of light is not met or crossed. Although I can see how this might make the issue experimentally irrelevant [..] it does not, I think, solve the problem. The problem is not what we can know about the entangled state; it is that the state involves frameless simultaneity.

Then I asked him: if this is right, then don’t we have to give up relative simultaneity?

Maudlin replied to me, making two points:

1) He agreed that my problem is a problem–and the typical physicist response tends to miss the point.

2) It doesn’t mean you have to give up relative simultaneity–it’s not a matter of logical necessity. It’s just easier to re-introduce absolute simultaneity. By easier, I take him to mean that it is simpler.

There is at least one alternative which keeps relative simultaneity: Roderich Tumulka’s ‘Relativistic Flashy GRW’ theory.* But many theorists find such an alternative quite odd. Which I take to mean: it is less intuitive than re-introducing absolute simultaneity.

I won’t repeat what he said exactly in his mails to me (nothing problematic in it–it was very helpful. It’s just I didn’t tell him I would make a post from it, and am not comfortable about quoting a private mail from without informing him).

Scientific Principles

I generally hold the following (many do):

a) A scientific theory–including a physical theory– should satisfy scientific principles such as simplicity, intuitiveness and actually being supported by empirical evidence. Given two competing scientific theories, the simpler, more intuitive position with more evidence is better.

b) All of those principles in ‘a’ are trumped by necessity. If denying it leads to incoherence and nonsense, a scientific theory can be complex, counter-intuitive and have no evidence** for it.

However, where competing theories are coherent and somewhat sensible (even if weird), the principles in ‘a’ can select between them.

c) Between the principles in ‘a’, I take it that there is the following trump order:

– ‘Evidence’ trumps ‘intuition': evidence for quantum physics beats its weirdness reputation).

– ‘Intuition’ beats ‘simplicity': the simplest view is there is absolutely nothing at all, you’re hallucinating all existence, and this doesn’t need to be explained (that x doesn’t need to be explained is always the simplest view).

d) It can be much more complicated between theories. Choosing between theories, one has to make a kind of global choice (something Maudlin points out to me).

Still, a global choice is about using the set of principles together. It doesn’t involve an extra principle which trumps all of the more local/specific principles (unlike necessity). You weigh up competing theories in terms of simplicity, evidence, intuitiveness, and see what you get.

e) There may be other principles beyond simplicity, evidence, intuitiveness.

The following are not principles of science or physics for a theory: that the theory has been around a long time; that its theorist is charismatic; that the maths is hard; that you can explain it at a party; that it’s getting you published; that the experiments are carried out in the Bahamas (what are you? The ’80s Michael Caine of Science?).

f) If Maudlin is right, it is simpler and more intuitive to re-introduce absolute simultaneity than to take on the alternative position.

That is, it is better to go back on Einstein’s abandonment of absolute simultaneity and a non-privileged frame.

I’ve been working on the assumption of relative simultaneity in most of my work. So that is an important conclusion for me.

—————

*Here’s a paper on that: http://www.jstor.org/discover/10.1086/675730?sid=21105898185781&uid=4&uid=3738232&uid=2 (not by Tumulka). Here’s a video of a lecture on that: https://www.youtube.com/watch?v=zDwKqB1XynQ.

**Although without evidence I’d tend to call that a metaphysical or philosophical theory–or, if evidence is possible, a speculative theory–but let’s ignore that for now.

Temporal Experience and Time Perception

In the next three posts I will follow-up on my upcoming paper on presence in time (see the last post). In this first post, I want to make a general point: that we should carefully distinguish between, on the one hand, time-perception and, on the other hand, time-consciousness and temporal experience. I want to raise it here in order to clarify in the next post what I mean by models of time perception. I think presence matters significantly to time perception; but it is not so obviously significant to the more general temporal experience.

1 Time Perception, Time Consciousness and Temporal Experience

In the literature, it’s common to talk variously about time perception, time consciousness, temporal experience, and so on. Are these all synonyms? Is every instance of (a) time perception an instance of (b) time consciousness And of (c) temporal experience? Or can ‘a’, ‘b’ and ‘c’ come apart from each other, such that ‘a’ can occur without ‘b’ or ‘c’, and ‘b’ without ‘a’ or ‘c’, and ‘c’ without ‘a’ or ‘b’?

I think that ‘a’ can come apart from ‘b’ and ‘c’ (and vice versa). I am not sure if ‘b’ and ‘c’ can come apart from each other and I tend to treat them as synonymous phrases.

Here is why I think ‘a’ can be separate from ‘b’ or ‘c': one might hold that (i) not all cases of experience are perceptual and (ii) not all cases of perception are experiential. As such, qualifying one of these with ‘time’ or ‘temporal’ does not give you the ‘time’ or ‘temporal’ version of the other.

Instances of experience are not always instances of perception. If there are instances of experience in remembering or imagining; neither remembering and imagining are perceiving. If one also held that there is cognitive phenomenology, and then held that phenomenology is identical to experience, then there are cases of cognition which are experiences; cognition (in this sense at least) is not perception.

Instances of perception are not always instances of experience. If there is unconscious perception, and one holds that consciousness is necessary for experience.  There are lots of theorists who think that unconscious, non-experiential, non-phenomenological perception is possible.

As such, when one talks about time perception, time consciousness and temporal experience, one must be careful to acknowledge that they might not be the same thing.

Not doing so can lead to assumptions and confusions about what’s being explained and how to explain it. One may provide answers which are inadequate and raise objections which are irrelevant.

2 ‘Time Perception’ is only different to other Temporal Experiences in terms of Quantity

The assumption that temporal experience and time perception refer to what I’m calling ‘temporal experience’ here: temporal experience includes durations beyond any we might see (or hear etc.) now–the experience in memory and anticipation, for example, or your experience of durations beyond your life–in imagining how long ago the big bang might be, or the death of the sun (the phenomenology of the time you are imagining).

Someone thinking about models of experiences of such durations, such as to the Big Bang,  is justified I think in holding that time (and temporal properties, relations, etc.) have to be something a human can only intend, imagine or in some way think about: such time is on an ontological and constitutional par with conceivable unicorns and the surfaces of inhabited alien planets. We can imagine, depict and think about time as we can think about unreal but possible things like unicorns. And, even if time is real, like inhabited alien planets, we must only think about it. To hold that we–humanscan really perceptually experience such durations is a mistake. It is not a perceptual experience like hearing rain, seeing your hand or a distant star. And so, we should conceive of ‘experiences’ of such durations as being more like the ‘experiences’ of imagined things.

Thinking this way about time and experience generally, without making an exception for time perception, we get the following. We apply this thinking to what some may call time perception, e.g., the time of what is perceived.  But such ‘time perception’ is misleading or misnomic. Even as applied to temporal properties and relations of things (and not Newtonian ‘independent’ time), there isn’t really a perception of such properties and relations. We don’t perceive the duration or temporal properties between now and the Big Bang. What applies to experience and the time related to the Big Bang also applies to all other experience and times. The only difference is quantitative, i.e., a matter of how long is the particular duration that we experience.

To identify general temporal experience with time perception is denied by many contemporary theorists. Read any discussion and comments on the specious present by, e.g., Broad, Dainton, Mundle, Grush, Le Poidevin, Kelly (and (of course) myself): there is a sense in which we may want to say that time is perceptually experienced–even perceived unconsciously, e.g., the perceived present of an apparently punctal event such as a lightning flash has duration, just not duration we’re aware of.

If we follow their positions, then we have reason to think that the difference between time perception and temporal experience generally is not just a matter of quantity but quality. There is a qualitatively different phenomenology, or even a categorical difference in the two experiences.

— One is like imagination, or is memory, or is anticipation–all of which I think are easily conceived as merely intentional and thought-like.

— The other is perceptual–the perceived change and the specious present. The latter is not as obviously thoughtlike, or like imagination, or memory.(It might be of course–there’s lots of literature out there on the idea of perception-as-cognition, cognitive penetration, etc. I don’t know how such theorists deal with the phenomenological difference between perception and thought, or even if they notice or are concerned with such a difference).

If this is right, time perception does not seem to be a mere matter of perceiving one thing and remembering another–which might explain longer durations–or of imagining a duration–which might explains ‘experiences’ of times like the Big Bang or durations such as that between now and the Roman Empire. It seems to be a perceiving of temporal properties such as order and temporal extent in the perceiving of one thing changing into another (change we hear, see, etc.).

3 ‘Temporal Experience’ is just a form of Time Perception

Similarly, If you thought that, whenever someone refers to temporal experience, they mean time perception, you could be confused in the other direction. Here is one way to get confused–by means of holding one or two further things. You hold that (a) perception always refers to present things and (b) present things are punctal.

Holding these, you might be puzzled by how there could be temporal experience other than the experience of whatever temporal properties are compatible with the present. So, for example, we cannot hold experience the past or the future–because neither is compatible with the present.

Yet, again, that we do have such experiences–however we characterise them–is right if the following is right: we have experiences of remembered events. Remembered events are past (of course, representations of remembered events need not be and neither need experiences of them, but that’s a separate issue).

4 Summary

1. Time perception refers to things like perceived change, time in the experience present, the specious present, etc.

2. Temporal experience refers to a more general experience. It may cover time perception but also concerns all other kinds of experiences involving time–whatever it is we call the ‘experience’ of durations over eons, etc.–i.e., imagined time–whatever we obviously remember and anticipate.

What I am concerned here with is models of ‘1’–models of time perception. I am not interested here in more general phenomenon of time consciousness or temporal experience. Because its perceptual character invites resistance to merely intentional or thought-like models of perception, I think it is ontologically interesting. I suspect how one models such time perception depends in part on one’s views of reality in time and the compatibility of presence with other temporal properties. I’ll cover that in the next post.