Philosophers have spent quite a lot of time and words on discussing what is
or isn't real
(in one sense or another – and therein lies most of
what there is to disagree about). As a physicist I care about what I get to
observe, what patterns lie therein and what models I can build that can make
sense of those patterns. Whether the observations
at the root of that
are an illusion, delusion, or other artefact of a system – perhaps an
allegedly true reality
behind my observations – that works
completely differently than the models we come up with is of no interest to me
at all. As long as the models physics comes up with suffice to account for the
stuff I get to observe, I don't care.
I don't care whether I
am a real
thing – or an artefact
of some delusions, of something in some truer
description, that happen to
cluster in a way that causes those delusions to have a sense of identity –
or an emergent subclass of the sub-state processes of a finite state machine
– or a subspace of a Hilbert space in which certain operators behave in
certain ways – or, indeed, a neighbourhood of a smooth manifold – or
any other model artefact that someone else feels like declaring to be the
true reality
; I only care that I
get to observe
certain
signals that I find to fit certain patterns that are well modeled by certain
formal systems – theories of physics. I don't care whether my delusion
that I am observing
something in my surroundings
is any of the
same kind of thing, just as long as what I do experience (delusional or fictive
as even my existence, much less the sense of experiencing stuff that goes with
it, may be) is tolerably well described by the models I'm using to make sense of
them. In practice I define reality to be the stuff I experience, and
tacitly presume that I really am something and my experience of
experiencing stuff is a real thing – in particular, it's stuff that makes
a big difference to what I experience; and making sense of it does enable me to
respond to what I experience in ways that tend to lead to later experiences that
I like better than the ones my model claims I would have experienced, had I
behaved differently.
You are perfectly free to reject my delusions of the reality of me and my
experiences. I do note, however, that I would not be writing this if I did not
entertain the delusion that someone (possibly no-one but a later version of me)
may at some point read it; I also invite you to notice that the very fact that
you are reading this implicates you in humouring that delusion at least enough
to allow that there is something you're reading. The very fact that we have a
means of communication open to us, that lets me write this and you read it, says
a great deal about the systematic structure of our experiences, which has made
it useful to you to understand the written word and has tempted me –
having seen the same usefulness for myself – into the delusion that there
may be some point to writing something, that you're now reading, even if the
whole of that point is to help me to remember this way of articulating the value
of a naïve
interpretation of the reality of my experiences.
Philosophical arguments about what is and isn't real
are really about
the semantics of that word real
; when Newtonian fundamentalists denied
the reality of the Coriolis and centrifugal forces – they're just
artefacts of the spinning frame of reference – they were asserting that
their model was the reality
and the experiences of folk in
spinning environments was illusory
. Einstein subsequently showed how one
can have a model (General Relativity) in which Coriolis and centrifucal forces
are exactly as real as gravity – indeed, they are aspects of
gravity, in the rotating frame. Either way, a kid sitting on a spinning
roundabout and manipulating things in that environment would be able to observe
the forces they describe. Philosophically, physicists side with the kid on the
roundabout – no matter what your model may be, we care about what
you actually observe. Philosophical positions that take some particular model
as given and only consider things real if they are in some sense essential to
the model, all else being illusion, are of no interest to physicists; and the
only way for the philosophers who take such positions to settle the question of
what is real is by declaring which model they have chosen to be sacrosanct, for
whatever reasons. This is a social dynamic problem, that the philosophers are
welcome to wallow in for as long as they like.
Meanwhile, physicists shall try to make sense of what we experience, while talking to each other and discovering that our delusion of having peers who experience essentially equivalent things is compatible with models we develop in conversation with those peers. When our social dynamics fails to settle a problem, we have a way of stepping outside the social dynamics and (metaphorically, at least) hitting something with a hammer to see how it responds, while describing to our peers the set-up and results we got, inviting them to repeat the experiment and tell us whether they get the same result. When we experience agreement with those peers, we trust that they'll accept our use of that shared experience as a grounds for consensus on what models are worth discussing. Whether you consider that consensus reality to be truly real, physicists have little reason to try to discuss any other reality with one another, aside from as an entertaining way to speculate about possible models we might build to describe the stuff our consensus says we get to experience.
Crucially, sane physicists distinguish between models that purport
to describe reality
and the stuff we experience – notwithstanding
that our models may describe it all in ways far removed from a naïve
account of our experience. To a physicist, what we experience is real:
everything else is model.
Written by Eddy.