This is also meaningless, scientifically: there is nothing you can measure which is outside the universe. Things like a holographic universe are inherently untestable. I hope we continue looking for testable things, but this speculative path rapidly leads away from science and physics and into "linguistic tricks to confuse humans". It's not even philosophy at that point, it's just arguing over semantics.
This is incorrect. Are you familiar with the inverse-square law? In 3-dimensional Euclidean space, the rate at which any force decays over a distance is inversely proportional to the square of the distance. This generalizes to n dimensions; but instead of the drop off rate being inversely proportional to the square of the distance, it becomes inversely proportional to the n - 1th power of the distance.
Suppose our universe is a 3-dimensional embedding of a n-dimensional manifold. Every local force we could empirically test would adhere to the inverse-square law, i.e. have drop off over distance k of ~ 1/(k^2). But theoretically speaking we could empirically test the dimensions of the manifold we reside in by identifying which power of distance is proportional to the drop off rate of extremely small forces where the compactified dimension can be detected.
For practical purposes this would require us to increase the precision with which we can empirically test (and reason about) forces at the subatomic level.
That's not evidence FOR the superverse, just like we can inherently not rule out the idea of the https://en.wikipedia.org/wiki/Evil_demon deceiving our every perception.
At best, this is untestable philosophy that's fun to debate over drinks. At worst, it's a tedious discussion about the semantics of existence and time.
Don't get me wrong! We could discover interesting things about our universe looking for holes, but there's no indication this problem is tractable.
Imagine if we came up with a super-universe theory that said that the super-universe could only spawn sub-universes which followed conservation of energy plus several other laws no one had ever thought to test before (and weren't implied by any other theories), and as we started testing for those other laws, every single one we tested turned out to hold in our universe.
(If that happened, it would be reasonable to look for simpler theories that also predicted those other laws too, but it's possible that the super-universe theory would turn out to be the simplest possible theory that fits. Theories should be judged by the complexity of their rules, not by the number or complexity of things they predict; a simple theory that implies a large ensemble of universes can be better than a more complex theory that implies only our world or what we can see is real.)
Let’s say you and me are little bits of algae which are floating in blob in the ocean off the coast. We are in a larger current which we cannot see. The current is such that we will eventually strike the shore together.
We are in a cluster of material together. It’s not exactly algae, there are a bunch of random gels, some mostly decomposed skin parts. Some very fine grit.
Of course the ocean is constantly mixing everything up, so even though we have been in this blob together for several weeks, that’s not exactly normal.
Well, there millions of blobs like ours, so I guess it’s sort of normal. But there are a quadrillion billion blobs that won’t last the hour. So our blob is, if not abnormal, improbable.
You and I are algae, so we can’t sense much. But we have noticed many events over our lives. Very early in our lives we perceived the day cycle. There are good times to photosynthesize, boy did we feel that. Time. We noticed quite a few bacterial... situations. And geometrically there have been a number of events in our blob. It used to be much bigger, for one thing. We certainly noticed every time a chunk got taken out of the blob and the energy gradients went haywire.
Of course we’re algae so we don’t remember, but we notice.
There is a world outside our blob, but we cannot know it. Sadly, this is physics. There’s not enough atoms in the blob to make a fin, let alone an eye or a brain. So there will be no peering out of the water at the sky. We can sense events within the blob. Outside the blob there may be more going on, but we certainly can’t see it.
There are unexplainable patterns in the blob. Why does it look sheared off on two sides? “We”, meaning our limited algae consciousnesses, didn’t exist during those events so we are just as cut off from our past as we are cut off from the world around us.
And we are barreling now, in a wave towards the shore.
And now we are floating.
And now we are rolling through a wave towards the shore.
And now we are slipping calmly on the surface.
And soon we will crash onto the sand, where we will be consumed by bacteria and insects, and our blob will be no more.
It is inevitable. The first law of algae says: you will be eaten.
But we will not be eaten this minute. And so I ask you: what happened in the blob, before it existed?
Luckily, though we can’t see outside the blob, we can ponder questions like this, because we are hypothetical blobs, and hypothetical blobs have human brains!
We can certainly guess what our bodies were before the blob existed. They were a cloud phosphorous and nitrogen. And presumably there were other plants or bacteria in our proto-blob that produced those nutrients for to become us.
That bit of skin I mentioned was on a dead whale. It was on the ocean floor but it got kicked up to the surface in a storm.
The gels came from jellyfish. And the salty water around us... well, it was salty water.
What shape was all that stuff in? A strange one. But still, we could draw it if we had some art supplies. And fingers. The current that brought in the whale skin could be drawn to an approximation. The bacteria largely came from two identifiable blooms, plus a long tail of about a thousand others, plus an unknowable tail catalog of origins describing the last 0.001% of bacteria in our blob. We couldn’t draw that, but maybe a light watercolor fog around our greater vicinity could represent it.
If I could draw our blob before it existed, it would look like a strange flower. With very long tendrils but also several beautiful simple twisted surfaces.
Now, what about the universe itself?
Science suggests its origins were not nearly so “soft”. Our blob was sort of “assembled” from pre-blob parts. The universe doesn’t appear to have been assembled in a soup that same way. Trend lines suggest it started as a singularity, not an assemblage.
But all physicists will admit we don’t have the technology to peer into those first moments. Like us and our blob, there’s just not the equipment available to look outside the universe to get data, nor was there equipment present to remember things as they happened.
We just don’t know what physics is like in those kind of moments. Is it an assemblage of parts from a larger vicinity? Are there even larger vicinities than our blob?
Or, to put it in terms that you and I would understand: did the universe, at birth, have a bit of whale skin in it? Some dead jellyfish bodies?
We can only speculate. As for me I say: why not?
But I’m just a bit of algae. What do I know.
Similarly it is hard to imagine any object that can be purely 2D in nature, because we are biased to perceive the world in 3D. So we think that every object has to be 3D, even the smallest organism, or even atoms. But a 'fake' example of 2D is a tv screen. It gives us an example to imagine 2D. The point I am trying to make is that time is just our perception. To say causality is always tied to time is a bias created by viewing the universe through a 'time' tinted/colored glass.
The point of singularity where gravity is so high that time comes to stand still, but is still present - this is a possibility.
So maybe time just pauses between big bangs and flows at lower density and lower gravitational fields
So is causality—I'm not really sure what your point is.
I am also confused a tad about the point I wanted to make though, lol. Maybe causality and time is perceived differently in higher or other dimensions that we do not perceive as of now in our human level of evolution. So the assumption of causality exists only due to time being present could be something relative to our perceptions and not true
p.s. for the record, Barbour is no clown, but a serious cat -- he is also the guy that wrote "Absolute or Relative Motion / the Discovery of Dynamics" which is a bedrock treatise on Machian ideas in physics
On the level of higher dimensions, it's difficult for us to perceive how cause -> effect would play out, but it's similar to how you would influence a drawing of a 2D stick figure. You could draw a house next to the stick figure, and that would cause the house to exist, but to the stick figure it would only perceive a single line with a start and finish on 1 dimension.
To that stick figure, cause and effect would be perceived as the two points on the line, though your four dimensional pencil caused it to exist on a different dimensional level.
• You can have causality in space rather than time: e.g. a convolutional image filter at pixel 13 might consider pixels 12, 13, 14 (of which the first two are causal and the last is non-causal, if we consider higher numbers as going "forward")
• You can have non-causal filters in time: e.g. audio compression at time 0:30 might consider not only the portion of audio from 0:00 to 0:30, but also the audio from 0:30 to 2:33. (This doesn't seem that remarkable, because the track has already been recorded, so it's not in "real time".)
• Finally, what we usually think of as intuitive causality in "real time" is simply a question of entropy. We think of a person dying because she was shot by a bullet, but we could also replay the movie backwards and think of all the tissues of a human body coming together in such a way as to propel the bullet backwards at a high velocity - in other words the wound causes the bullet to fly! The only reason we don't think of it this way is because the latter explanation decreases rather than increases entropy. As it turns out, physicists can show that entropy is also the exact reason why we remember the past and not the future. (And if we did remember the future and not the past, we would simply think of the future as the past and vice versa, so things wouldn't feel any different.)
This is not a god argument, there might be natural processes that can trigger such events.
We really don't. We don't have any physical evidence of anything from before the big bang (presuming that's what we call the "beginning"). Zero. All we have is people having views on the current situation, trying to apply those views backwards to "before", where they may or may not fit, and saying "I think it's like this".
You could - hypothetically - pause the computer, check its state, change a few variables, and the simulation would experience instant modifications.
A slow simulator could take many "real" time units to calculate each in-simulation time frame - and this would be invisible in-simulation.
And so on.
You have a fully causal system, but the simulation is ruled by its own independent emulation of causality.
Of course a computer implies a conscious user. But let's attempt some wild speculation and suggest that a "simulation" could also be a completely natural process - something that happens in a much bigger causal substrate: a kind of causal symmetry breaking, where a subset of possible relationships crystallises out of a bigger set of possibilities and then continues independently, losing some degrees of freedom.
A simple two level topology is the simplest possible model. But "causality physics" could allow all kinds of topologies - nested, circular, fractal, etc.
I don't think that's "by definition". That's by observation of an example of one.