We live in a very strange universe indeed.
In some ways, it’s a kind of illusion of what happens, an echo of the quantum world
that underlies everything.
We are tempted to think of things in terms of classical objects, when one picks up a
glass and takes a drink from it, that is a classical interaction with an expected outcome.
But on the quantum level, things are very different and particles can exist in a superposition,
in other words all states at once, until observation or interaction collapses them.
This is well proven.
Quantum effects are used in electronics, and the infamous double slit experiment shows
particles in the act of behaving as waves or individual particles when under observation.
This has led to some very far reaching and very bizarre notions within quantum physics
including the question of whether the universe exists at all when it’s not being observed,
which it does, even a particle in a superposition is still a particle and interaction with inanimate
classical objects causes it to choose a state.
But hidden within the history of physics are some very interesting possibilities, but it
really depends on which interpretation of quantum mechanics you go with.
There are three major ones.
The most widely accepted is actually the spookiest one.
It’s the Copenhagen interpretation of quantum mechanics.
This involves the infamous Schrodinger’s cat thought experiment, where when something
is not being observed or interacted with, it’s in a superposition.
Think of it as getting fuzzy.
Only when it’s observed, essentially interacted with, it collapses into a state.
All possible outcomes reduce down to one.
If you just go with the Copenhagen interpretation, then weird things happen.
One of these is a thought experiment proposed by physicist Eugene Wigner in 1961, sometimes
known as Wigner’s friend.
Essentially what happens here is a coin toss that establishes two different realities calling
observation itself into question.
So say you are performing a coin toss in a glass isolated booth, and you have a friend
across the room watching you do it.
If you apply the rules of quantum mechanics to observers and people holding coins, the
universe gets weird indeed.
So the coin you are tossing is in superposition, it’s both heads or tails before you toss
it and create an outcome.
You see it as tails, but your isolated counterpart on the outside doesn’t have access to that
information.
Therefore they describe it as being neither heads nor tails but in superposition.
That gets into entanglement, one outcome affects the other.
From this you can do what’s known as an interference experiment and determine the
superposition of the system.
This creates an issue.
The end result is two perceived different realities.
But the question is just a thought experiment.
Humans are not quantum objects.
But the real question is could it be tested.
Can measurements in quantum physics really be subjective to whoever is observing it?
It doesn’t get more messy than that question, because it calls the reliability of observation
into question, something science depends absolutely on.
These ideas were furthered by John Bell, known as the Bell Inequality, which if it’s violated,
then you end up with two sets of facts from two different observers.
More recent work however has shown that the Bell inequality can be violated, meaning that
there actually isn’t any such thing as an objective reality.
That’s assuming several things, including that signals somehow can’t travel faster
than light, but we don’t actually know if that’s the case.
We simply know that the universe seems to prevent the transfer of meaningful information
faster than the speed of light, but it doesn’t prevent the transfer of random information
faster than light, which is spooky action at a distance.
But does show, on the quantum scale, that what is seen as fact may not be the same to
all observers.
That said, under any normal conditions in which we as humans experience the universe
on a large scale, the facts are safe.
Now there are other interpretations to quantum mechanics.
One of these is the many worlds interpretation where there isn’t really a superposition,
but that all realities split off from each other creating universes that cover all possible
outcomes.
An almost infinite number of parallel universes is cumbersome to say the least, but may be
the case and does have its adherents in the scientific community.
The last possibility is that the weirdness of the Copenhagen interpretation is mitigated
by something that keeps quantum effects on the quantum level, at least most of the time.
In other words the world of the big presents a situation where quantum effects somehow
cancel out.
But not always.
In this case, you can occasionally, if you wait long enough, and we’re talking more
than the current age of the universe, quantum effects such as quantum non-locality could
telescope up to the world of the large.
That’s bad news, that could mean that it’s possible in the universe, if beyond highly
unlikely, that one moment you could be sitting in your living room, and the next you have
teleported a billion light-years away in deep space.
Not good, but thankfully it’s so unbelievably unlikely that it only ever happens in infinitely
lasting universes.
But particles themselves are basically non-local, they do this all the time.
But what we do see is that causality seems to rule the world of the large.
One event leads to the next, and so on, and as the soft-sci fi but quite good overall
TV series Lost put it, what happened, happened.
But that may not be the case.
Cue in one Dr. John Archibald Wheeler.
People often ask me regarding Event Horizon interviews, out of all the scientists that
are no longer with us which one would I want to interview the most.
They often ask if it’s Einstein, Enrico Fermi or Carl Sagan, but in reality it’s
Wheeler.
Few in physics have come up with as many interesting, and still unexplored ideas as he did.
Wheeler asked a puzzling question.
Maybe instead of a set past, the universe actually functions as a feedback loop that
sets the past as it moves forward in time.
In other words, our actions and that of the universe’s humdrum day to day interactions
are actually solidifying the past.
This gets back to the double slit experiment, where photons can behave as waves or particles
depending on if they are being observed by detectors of whatever sort.
Wheeler added something to this by taking it on a much grander scale.
A double slit experiment involving most of the universe itself.
And the implications are really strange.
So imagine a very distant quasar, an energetic galaxy from the early days of the universe.
It’s distant in both space, but also time.
You’re seeing the light from it ostensibly billions of years after it left the object,
it just took the light from it that long to get to you by crossing space at the speed
of light.
Now imagine a pair of foreground galaxies in front of that quasar causing gravitational
lensing.
You can see this effect in this now famous James Webb space telescope image, gravitationally
powerful objects can bend light sources around them as a lens, which is what’s happening
with our quasar.
Incidentally, that we see this effect serves as yet another confirmation of General Relativity.
You are seeing Einstein’s work in the distortion of this galaxy’s appearance from our perspective.
From another area of the universe, it would appear perfectly normal.
So in Wheeler’s experiment, the two foreground galaxies substitute in for the double slits
in the original experiment, and the light from the quasar stands in for the laser.
So this gives the two different paths needed for the standard double slit experiment, though
there are other ways to perform it.
There are youtube videos on how you can do it with a laser pointer and a strand of hair,
should you wish to see at least part of one of the strangest aspects of the universe in
your living room instead of quantum tunneling to another star system.
This means that photons from the quasar can follow two different paths to your eye, as
in the classic experiment.
When viewing the bent light from the quasar, the telescope becomes the detector.
If they look at one of the foreground galaxies, or the other they should in this case get
the same result either way.
But if you combine the two images using mirrors so they line up simultaneously, you’d see
the standard interference pattern of the double slit experiment.
If the quasar was faint enough, you’d have individual photons hitting the detector one
at a time.
Here’s the strange thing.
The result wouldn’t change.
You’d still see the interference pattern which means that both photons acted as waves
passing through intergalactic space and followed BOTH paths simultaneously even though the
paths were separated by potentially millions of light-years.
And if that isn’t enough of a problem, the choice on how the astronomers use the telescope
to make the measurements and design their experiment weighs in here.
Wheeler noted that this ultimately means that the measurements made in the present determine
a photon’s past, whether it travels one or both routes.
Known as the delayed choice experiment, Wheeler’s idea has actually been proven in the laboratory
since the 1980’s.
This leads to a very strange universe indeed.
Wheeler himself conjectured that we are incidences of the universe observing itself, and ultimately
building itself and the whole of the universe is not finished yet, and indeed may never
be.
The act of observation, whether done with our eyes or our detectors, we select and force
the definition of history on the quantum scale and it’s not really fully written.
But you have to be careful here, observation is a tricky word in this case.
The potentials can also be brought about by classical matter of any type.
But as far as particles go, the past does not solidify until it interacts with something.
It could really be that our universe is made up partially of uninteracted particles in
a quantum superposition, photons traveling the blackness of space from the days just
after the big bang with histories and outcomes that are not defined until they interact with
something over 13 billion years after leaving their source.
Somehow this may be related to other oddities in physics.
A good example here is to look at the life of a photon.
Traveling at the speed of light, again due to relativity, a photon does not experience
time.
To it, it gets emitted and it interacts simultaneously even though from our perspective it may have
taken billions of years to pass through immense amounts of space.
Is it any wonder then that the history of a photon can only be written from its future,
since past and future don’t exist to it.
In Wheeler’s view, the past is not yet fixed.
But I leave you with this.
In physics there is no now, the present doesn’t exist and there is only the past and the future.
The present is some sort of human construct that can’t be defined according to the theories
or mathematics.
How the present is measured depends on where you’re observing it from.
But if that’s the case, and Wheeler really was on to something, how does this all fit
together if an observation in the now defines the history of a particle.
We may never know.
Thanks for listening!
I am futurist and science fiction author John Michael Godier currently concerned for the
welfare of the photons.
Instantaneous existence isn’t much of an existence.
And their job looks hard, just to provide some light in the universe they have to travel
at the very fastest possible speed.
Talk about rushing around and stress.
It really is a thankless job, especially compared to a proton sitting doing not much of anything
in the nucleus of a boron atom and be sure to check out my books at your favorite online
book retailer and subscribe to my channels for regular, in-depth explorations into the
interesting, weird and unknown aspects of this amazing universe in which we live.