It's big, very very big but... 1. Big Bang Cosmology says that universe however big must be finite, if so, then A. Can the universe have spin. B. Can it have translatory motion. C. Can it have inertia. D. Can it have net non zero energy. A and B certainly must be zero, because there is no FoR outside the universe, in my opinion C must also be zero because inertia is with respect to resistance to external force and there is no external force.
Data shows otherwise. But, as I have posted elsewhere, we do not know one way or the other what it is at present. Age has nothing to do with it being infinite or not. Also we do not know how, or what, started it.
https://phys.org/news/2016-09-scientists-universe.html A. This confirms the known universe doesn't spin, that estimate good to at about one part in 10^5. Not much certainty there, but it's something. One wonders just how long one would need to observe it in order to make a better estimate. B. Translatory motion would evidence as a spin on a larger scale as well, AND EVEN if one were able to detect the entire universe had translatory motion with respect to something, there would literally be no means for determining which one was moving, and with respect to which. Einstein already showed, no absolute motion, no absolute time, no absolute space. C. Space can definitely have inertia. Matter has inertia, and the universe has matter. D. The Goldstone boson example of Higgs shows that space evidently does not have zero net energy.
But, if one defines a point to have specific dimension (size, for instance), there are only a finite number of such points on a finite line. Dimensionless points are math fabrications, IMO, of course..
May I dispute C and D? For C pl refer to Mach, for argument sake only. For D, what is the quantum of this non zero energy.
Thats interesting because this demonstrates that maths can create absurdities too, and every solution or representation of maths need not be meaningful. Take for example BH singularity, it is a point but with infinite density, curvature etc. How can you define volume or density for a point? How can mass reside at a point? This all appears to be a mathematical artifact but has taken a cult status.
For C, I probably should have said: "Matter has angular momentum, and it it exists. Angular momentum is also inertia, but of a kind that obeys Special Relativity's rule that no absolute (linear) motion derived only of it. It needs a boson, that's what." For D, I mean, the VeV of space is set at about 250 GeV last time I saw someone provide an estimate. That's not zero.
But for A and B it is null, net angular momentum of universe is zero. Non zero value of C does not tally with your response on A and B. And wildly speculative scenario....what does this total mass of universe curve or bend or warp? Looks like GR is not applicable here too? Is it suffice to say that a finite universe with mass and energy has no spacetime to curve?
Curvature (of a trajectory or of a beam of energy) implies a force acting on it. A particle of matter possessing inertial mass has curvature. THEY TEND TO BE ROUND, and that is curvature, is it not? Has to be a force acting there to make it round. Behold, the Higgs, the ONLY G-damn gauge boson associated with NOT A SINGLE FUNDAMENTAL FORCE ANYONE COULD IMAGINE. Can you? Spinning things have inertia. There is power in understanding what inertia is. Energy that is bound has inertia. You can make unbound energy have inertia too, simply by using only as many reflective surfaces as necessary to keep it absorbed and emitted from a reflective surface composed of free electrons. Photons in free space carry inertia too, but in only a single direction, and it has no rest inertia in every direction like matter possesses. Whole planets and stars tend to be round too. Coincidence, or a periodicity of scales? Even spiral galaxies are round in a plane. You decide. Thank Cap'n Obvious, not me. Just providing the missing vocabulary here. Your science won't understand, for at least another 1,000 years, the spiral galaxies are the ones that tend to have a large number of solar systems ('exoplanets') orbiting their stars, whether they are all habitable or not. Because unless Cap'n Obvious just mentioned it, you'd uderstand nothing at all about the periodicity of scales. Did you all learn nothing from your slide rules or log tables, other than to trance out looking at the pretty numbers and gradations? This is also the reason, the temporal permanence of particles on the quantum scale is repeated on scales in which light requires 180,000 Earthbound years to traverse the Milky Way. Things on both scales barely change at all, as you observe them from an intermediate scale. Protons take forever and a day to decay also. If they did not, the larger scale would also never happen the way it manifestly has. Stupid hominid bipeds and their primitive proportional mathematics. They were OBVIOUSLY made for each other.
This "whole universe" Vs Gravity could be quite painful for GR. Einstein's field equations (EFEs) with Cc talk of accelerating expanding universe, fine new spacetime is created, but I feel the actual utility of EFEs is to find out the curvature beyond the object, that is if present size of universe is R (assuming spherical) then EFEs are more meaningful if r > R, but that does not exist, so EFEs are not applicable to whole of universe, with this expose claiming that universe is expanding under GR interpretation, then its bad. GR as the theory of gravity is not applicable on whole universe. Shocking it has problem at other extreme ...quantum level..
If you define it to have dimensions, it is no longer a point, though. A point is a mathematical fabrication, the utility of which derives from it having no dimensions. It is necessary to enable geometrical figures and constructions to be defined exactly.