Status of the block universe in the field of physics

Morbert wrote: »

No, not contrary to anything I said. In the other thread, I have said multiple times that relativity is compatible with presentism if you presuppose special dynamics that are undetectable.

Surely 'presentism' only acknowledges the dynamics that are detectable, i.e., energy exchanges as they occur.

It is only by assuming a 'present', any 'present', that we can derive the laws of physics but we can get around this 'assumption' by saying that any 'now' can serve as a frame of reference.

An experimenter simply 'timestamps' a series of observations that are made during what the experimenter consistently would term as 'now', and those observations chart energy exchanges. Only what are perceived as events can have any validity as experimental data, all other data has to be deduced or recorded by a different experiment.

So, every valid piece of scientific data in existence comes from perceived events. What we don't, or can't, perceive has to be deduced and is therefore never experienced.

What use to science is the block-universe if it says nothing ontological about the universe? And why should this model be accepted over other, non-ontological models that are consistently dismissed out of hand in a manner that is comparable to how religion dismisses non-orthodox views?

Why the hero worship?

How does the block-universe predict the physics we have?

It doesn't. It is simply a way to visualise that which many physicists in the vein of Feynmann say can't, and even shouldn't, be done.

We can't experience what the sun is made of so we have to deduce it from data from events we can experience. But the events we experience are not the events we are trying to deduce, they are events caused by the photons that were created by the event we are trying to deduce. We have to collect many photons from many events in order to work out that the sun is largely made of hydrogen but we never experience the hydrogen directly.

So I'm just wondering, what aspect of Roosh is it that can be experienced by a being 50,000 light years distance away in 50,000 years' time apart from photons that bounced off him? These photons have no connection to Roosh, they are simply the result of events that occured in the space occupied by Roosh. That distant being should realise that what he experiences says nothing more about what Roosh is other than his possible position. That distant being could learn nothing about the fact that Roosh is a carbon based lifeform who breathes oxygen, or that he wears a tracksuit, the photons he receives tell him nothing, he can't even say where a particular photon originated, the surface of Roosh's eye or the surface of his retina would be indistinguishable.

I know it wasn't you who brought this up but you don't seem to take issue with the claim that a distant being can experience Roosh directly long after Roosh shuffles off this mortal coil.

We don't perceive events that occur, we try to deduce the events that occured from the events that we do experience, events like a photon interacting with a telescope.

Those who are experiencing a tsunami are not experiencing the earthquake that caused it and we don't say that hearing thunder is like being struck by lightning, so why should we say that the gamma rays that arrive at our detectors are a direct experience of a supernova explosion, that we are observing events from the past?

We're not, we are experiencing an event caused by a photon being perceived now, in our present. The photon takes part in two events, the event that created it and the event that occured due to its subsequent absorption, perception. The two events are unrelated, they just have a photon in common and the photon is an object of chance. We can't detect the creation of a photon, we can only ever detect its absorption. Suppose the emitted photon is never absorbed, does that mean the creation of the photon never took place?

At least presentism does have ontological status, I perceive therefore I am. Whatever it is that I am, I am affectable. I put my hand in flowing water and the current exerts a force on my hand that I feel, I perceive a process of change occuring, but only because I participate in the exchange of forces. I see the water move and I feel it push my hand but still I might put my hand into a bucket of water to see if it feels as differently as it looks and I will deduce that water is made out of a substance that when in motion can produce a force.

There is no other way, stick a probe in and make it take part in the energy exchange process and come to conclusions based on what the probe perceives. The probe is only providing data when it is directly involved in collisions.

And it shouldn't take thousands of years of science to realise that. All the measurements we can make are through determinism. I can't tell you what it's like to be caught up in a tsunami, you have to be there when it actually happens. Touching my wet clothes is not experiencing a tsunami. When I am relating the experience, I'm not experiencing a tsunami, I am examining data directly obtained from being in one in the past.

So what do you have against presentism? And when did you decide that unmeasurable concepts are good for science?

At least determinism does allow us to make predictions albeit with certain caveats due to unknown variables or changes to variables. At least determinism roughly explains how everything in the universe will proceed from this point on.

Only collisions cause change, no collisions, no change. But change occurs. We see it, feel it, measure it. Collisions. If a system stops experiencing collisions then all its components travel away in a straight, Newtonian line and wouldn't be interacting with one another.

But then it wouldn't be a system would it? It would be debris of a system that no longer exist.

In order for there to be time between moments of change, we would have to explain how magnetic forces and charge 'switch off' between those moments. Because that's what the block-universe means, there are contiguous slices where the universe undergoes either no change of state at all or that any change of state is because all the components behave as if they are not subject to any forces and taking Newton's advice, continue in a straight line until acted upon again by a force that will come into affect in the next slice.

Do you see what I mean? There would be configurations of the universe where charge and magnetism wouldn't be manifest as an effect.

But there is no need for that since objects move as if they are subject to the constantly varying effect of gravity.

And another enemy of the block-universe is entropy. The 4-D universe can't see entropy, each slice is in perfect order. Especially if they were all created instantaneously. I am prepared to say that laws of thermal dynamics and therefore entropy are in fact ontological statements of the universe and they are presentism's best friend.

If we accept that the universe is constantly expanding then we can define entropy as - the tendency for the number of interactions that take place in the universe to become fewer as the universe increases in volume. If we can go with this then entropy is the result of an expanding universe as it undergoes cooling.

We might then ask - why does the universe have to go through a cooling process, why didn't it go from hot to cold instantaneously?

We're actually asking, how did time come to appear in the universe?

A determinist might say, well, if inertia, the tendency to resist change didn't exist then that is exactly what would have happened. Without inertia, the universe would have gone from total chaos to a state where all its components have their final velocities and trajectories. And in an instant.

There would be no universe.

But there does seem to be one so a determinist has to explain inertia and thermodynamics says enough.

Think of a bucket of boiling water that has been gently lowered into a glass tank of cold water and then the bucket is tipped so that it empties onto the floor of the tank. If we observed this experiment in the infra-red spectrum then we could follow the heat distribution process.

If the water is unagitated then we would notice that the volume of hot water maintains a border with the cold water for quite a long time. The heat seems to travel very slowly as the cold water begins to warm up.

This is because the only parts of the water that are 'aware' of a temperature gradient are the ones at the edge, The molecules that are located internally cannot 'decide' on the correct path because they are colliding with objects of equal energy. It is at the border where hot meets cold where the hot water gives up its energy and that same border tends to contain the internal energy.

If all the hot molecules could sense the cold they would instantly obey thermodynamics but most of them find themselves on initial paths that lead from hot to hot and that is manifest as impudence (:)) to the 2nd law. But the law is strict, only paths hot to cold are allowed and the system is punished by a loss of energy. Impedence, resistance to change, only slows thermodynamics down, eventually, all systems lose their energy.

Inertia!

And the entire system, hot and cold is in motion even betwen collisions when energy is stored as momentum. The system undergoes constant change even when the energy is perfectly distributed among them - two systems become one that is itself subject to thermodynamic law.

But the main thing is that after perfect mixing, both of the original systems have ceased to exist and can be safely ignored by determinism.

Imagine that the bucket of hot water is a single photon. The number of molecules represents the energy of the photon and the tank could be an electron. The final state of the tank is the electron in a higher orbit.

Of course, the bucket is emptied with such force that all the hot molecules quickly find a colder one and the 2nd law is happy.

Another good example of inertia - look at the energy contained in the modern physics community and how it resists change by sticking to a hypothesis just because it is not broken yet.

Can you really justify your stance against presentism when it works so well at every scale and without the need to consider time as anything but a concept that allows us attach meaning to our observations of change.

It is not 'time' that flows it is the transfer of hot to cold that flows, energy.

It is not 'time' that speeds up or slows down, it is rates of exchange of energy between hot and cold systems that varies.

Energy - what there is

Presentism - where it is

Determinism - what happens next.

Now - existing there

Thermodynamics - the law.

Result - an observable universe that exhibits entropy.

And all this from assuming that the universe is constantly expanding.

Why have slices when you could have the whole cake?

If nothing changes in each slice then how can each slice be different.

Although, if a 3-D space is taken as a set of starting conditions, then the time dimension can be viewed as points along which an iteration of a transformation process is applied to that space, x amount of time causes x number of iterations.

But even here, it is the same space being transformed as opposed to being copied, pasted, transformed and then being presented to perception.

The idea that time is a force that transforms is much more palatable than time being the entire set of events that constitute the past, present and future of the entire universe.

Morbert wrote: »

It is a formalism that makes elegant predictions about what we observer in experiments ranging from gps satellite comparisons to particle decay to the very creation of particles themselves. With an accuracy of 0.0000000000001

Does that improve on what relativity can achieve?

Morbert wrote: »

General relativity says you cannot map one slice onto another. The closest we can get is applying a metric to similar slices.

Okay, I'm a little unsure if we disagree on anything here.

We are not saying that 'moments' in time are like 'addresses' of memory locations that contain a particular configuration of the universe are we? That the same address always yields the same universe?

And if we are, there is the requirement of knowledge of one configuration in order to 'deduce' older and newer slices by applying a metric to known initial starting conditions?

But we are definitely not saying that the time component of the co-ordinate contains the precise information about both the metric to be applied and how it is applied (assuming time-dilation events that occur need to be considered locally), are we?

Do you think that all future and past events exist simultaneously and persistently? If the sun exists as a mass in an infinite moments of time, that is an awful lot of mass that it local to us in time terms. 3-D space may only experience one mass of the sun but there is a great deal of hidden mass either side of any particular 'present'. That amount of mass could be expected to have a huge effect on points in 4-D space.

Dark energy maybe?

Anyway, I chose option 5 in the poll, I think the block-universe model is a philosophical concept that does have a place in physics.

Like 'time' does.