What is Space? The 300-Year-Old Philosophical Battle Still Rages Today

[C C]

https://www.space.com/38791-what-is-spac...rages.html

EXCERPT: [...] You might think physicists have "solved" the problem of space. The likes of mathematician Hermann Minkowski and physicist Albert Einstein taught us to conceive space and time as a unified continuum, helping us to understand how very large and very little things such as individual atoms move. Nonetheless, we haven't solved the question of what space is. If you sucked all the matter out of the universe, would space be left behind?

Twenty-first century physics is arguably compatible with two very different accounts of space: "relationism" and "absolutism." Both these views owe their popularity to Caroline of Ansbach (1683-1737), a German-born Queen of Great Britain, who stuck her oar into the philosophical currents swirling around her.

Caroline was a keen philosopher, and in the early 18th century she schemed to pit the leading philosophies of her period against each other. On the continent, philosophers were stuck in "rationalism," spinning world theories from armchairs. Meanwhile, British philosophers were developing science-inspired "empiricism" – theories built on observations. They were worshipping scientists such as Robert Boyle and Isaac Newton.

Caroline asked two philosophers to exchange letters. One was the German philosopher Gottfried Leibniz, rationalist par excellence. The other was the English philosopher Samuel Clarke, a close friend of Newton. The two men agreed, and their exchange was published in 1717 as A Collection of Papers. The dull title doesn't sound like much, but these papers were revolutionary. And one of their central issues was the nature of space....

MORE: https://www.space.com/38791-what-is-spac...rages.html

[Syne]

Funny that the absolutist was the empiricist and postulated god. No, that's my presentism speaking. Empirical science was largely driven by beliefs in divine, eternal design.
Leibniz was a brilliant philosopher, whose ideas of space were much more prescient of modern science, e.g. relative motion, the metric expansion of space, etc..

[stryder]

Q: What is a space man?
A: Something you park your car in, Man.

I don't like to go on about my personal thoughts on the subject much, mainly because I spent way too much time on the theory and very little time trying to compose it in a way that others could make sense of it.

To me our linear perspective of the universe is actually a multiworld's composite. Where parallel layers of existence entwine to generate substance. Vaccums are potentially a way to bridge a parallel into the same linear level as the initial multiworld state. This rationality implies that the universe therefore has to have a "container" for this function in and thereby means that you can never have a "perfect vaccum" since you would always detect elements of that container.

The rationality in regards to multiworlds was in relationship of theory in both "Simulating a universe" and how to make sure the universe was indeed "Infinite", as generating duplicate parallel layers and being able to bridge them back into the initial multiworld state would lead to constant expansion as we'd never run out of energy. Some might consider this to break the "Law of Conservation of Energy", however again this is really dependent on where you apply the "container" of energy actually exists, is it at the level we currently observe or a level that is currently unseen (such as parallels in a multiworlds framework)?

[Zinjanthropos]

I'm always reminded of my aquarium whenever this topic comes up. The fish in the tank are in their space(universe), sort of. That space is not a void but a substance. A substance that allows for the free movement of things within it. Does that make space an ultra fine pulverized medium of particles  that allows the same freedom?

If there was BB singularity then over the eons has it continued to spread itself thin? The BB by its own powerful forces may have created its own medium(space). I guess its still here, not going away, simply playing out whatever it is a singularity does over time and we're part of it. Was there ever a void or are we and everything else including space still components of an object?

[Yazata]

You might think physicists have "solved" the problem of space.

I don't think that. But yes, physicists certainly try to give laypeople that impression. 'Space' is whatever we say it is.  

The likes of mathematician Hermann Minkowski and physicist Albert Einstein taught us to conceive space and time as a unified continuum, helping us to understand how very large and very little things such as individual atoms move.

Space has been conceived of mathematically, in terms of geometry, at least since Newton and probably long before that. I don't think that Einstein and special relativity really changed that, it just made the metrics of how distances are measured a lot more complicated.

Nonetheless, we haven't solved the question of what space is.

Right. (Not even close.)

If you sucked all the matter out of the universe, would space be left behind?

'Vacuum' has historically been defined as space devoid of matter. The question becomes, if space is totally devoid of matter, what (if anything) remains? Just the bare possibility of geometrical properties like distances and direction (should material objects exist)? Or something more substantial that isn't dependent on the existence of matter?

In my opinion, the thing that's really challenged that 'space as nothing more than the possibility of geometry' conception are the concept of fields and all that quantum mechanical vacuum-energy, zero-point energy, wave-particle duality and virtual particles stuff. Space isn't just an empty stage any longer, where material things happen. It seems to have all kinds of physical properties of its own and starts to look increasingly substantial, becoming a kind of stuff in its own right.

It seems to me that matter and space might be pretty much inseparable. Material particles simply become particular kinds of excitation of space. Eliminate all the matter excitations, and you have unexcited space-stuff. (The quantum fields of quantum field theory.) Or at least space-stuff occupying its lowest energy least-excited quantum state, which is going to be subject to quantum uncertainty. (Hence a constant creation and destruction of virtual particles down there on the tiniest microscale.)

Twenty-first century physics is arguably compatible with two very different accounts of space: "relationism" and "absolutism."

To me, the more interesting distinction is between thinking of space as void, as nothingness, and thinking of it as an all-pervading plenum.

The controversy might go back to Parmenides and his followers, to the idea that 'non-existence doesn't exist'. Plato and Aristotle basically agreed and insisted that true vacuum was impossible ("nature abhors a vacuum"). Galileo and notably Descartes followed that tradition and thought of space as a kind of universal frictionless fluid, a plenum. But Newton and his successors favored the pure-geometrical concept. (Newton thought of space as God's "sensorium", God's field of awareness. Kant promoted a similar idea.) The space-as-void concept competed with various ether theories until the end of the 19th century. The vacuum pump experiments of people like Toricelli were conducted in this intellectual context with these controversies in mind. James Clerk Maxwell, the electromagnetic field guy, favored the plenum side which is one of the reasons why he favored the idea of ether. But by the early 20th century the vacuum-as-void nothingness-idea seemed to have decisively won, in high-school physics classrooms at least. Space was just the empty and vacant stage-set upon which material events occurred. It was where things like distances existed, but distances were just relational properties dependent on the existence of substantial material objects. (Suggesting an extremely hard materialism.)

Except that the quantum mechanics that was appearing at the same time and the subsequent quantum field theories that developed out of it seem to generate new reasons for thinking of empty space as a kind of physical substance in its own right.

https://en.wikipedia.org/wiki/Vacuum

https://en.wikipedia.org/wiki/Vacuum_state

https://en.wikipedia.org/wiki/Vacuum_energy

https://en.wikipedia.org/wiki/Zero-point_energy