Did you ever notice how perfectly everything fills up the space it would leave if it weren’t there?
Just like Mark Twain’s observation that somehow there is always enough news every day to fill up the newspaper…
Or the Douglas Adams quote: " This is rather as if you imagine a puddle waking up one morning and thinking, ‘This is an interesting world I find myself in — an interesting hole I find myself in — fits me rather neatly, doesn’t it? In fact it fits me staggeringly well, must have been made to have me in it’…"
Hence the undeniable truth: there is no universe.
Obviously, it’s all just the Red King’s dream…
I like Brian Greene, I haven’t read that one - thanks for the suggestion.
That’s interesting, so do I understand correctly that the strong interaction/force existed before matter? (I appreciate the link)
Temet Nosce.
Here’s another interesting seeming coincidence that, AFAICT, has no official explanation, regarding the relationship between the quarks / baryons and the leptons. Why is it that the charges of the quarks come in 1/3 or 2/3 of the amount of charge that electrons have, so that a proton has exactly the same amount of charge, only opposite that an electron has? It seems to me that the only reasonable explanation is that there is some more fundamental particle that makes up electrons and quarks, only put together in different ways.
It’s all in my head.
AKA a “Grand Unified Theory”
What blows my mind is superstring theory, advocated by Greene. 10 dimensions of space plus one of time. 7 space dimensions are not noticeable at macro scales.
It’s debatable whether it’s “coincidence” that electrons and protons have exactly the same but opposite charges. One can appeal to the anthropic principle and say that if this were not the case, then matter as we know it, and consequently the universe as we know it and we who observe the universe could not exist. It’s the same argument as why certain physical constants have precisely the values they have to allow stable matter to exist and for complex organic compounds to form and ultimately produce life. It may be otherwise in other universes, but there’s no one there to remark on it.
As for particles more fundamental than quarks and leptons, you have to get into the uncharted waters of string theory to pursue that. The Standard Model has been very successful with its arrangement of two quarks (up and down), two leptons (electron and neutrino) each of which has a second and third generation counterpart, and all of which are considered fundamental and indivisible. I see no reason to be bothered by the fact that the up and down quarks have fractional charges relative to the electron.
Thanks for saving me typing. That’s it exactly IMO.
Depends on what we find out. We could be some kid’s science project in a universe we can’t even imagine. Maybe no speed of light or relativity, or nothing at all resembling the physical world we thing we observe. Of maybe just a very similar universe but the food is much better, or worse.
Seriously difficult to get around that question in a rational manner. Even if it’s all my imagination where did I and my imagination come from? Turtles all the way down.
Which also suggests by the principle of mediocrity that it’s also turtles all the way up, and we’re somewhere in the middle of the stack.
Mind. Blown. 
Theoretical physicist and cosmologist Lawrence Krauss addresses the question “Why is there something rather than nothing” in what is essentially a four and a half minute summary of his book of the same title:
OK.
So why/how is there gravity?
Because what he seems to be saying is that when “nothing” interacts with gravity, something appears.
But gravity is something.
ETA: Note: I am not a physicist. Maybe I’m missing something there. But he’s trying to explain it to non-physicists, no?
Beat me to it. That kind of jumped out to me as well.
Also it was mentioned upthread that all of the forces were merged as one at the moment of the creation of the Big Bang, so does that mean that not only did gravity exist independently of the universe, but the other forces as well?
No, I don’t think that’s quite what he’s saying. Krauss has always been a big fan of using quantum fluctuations in a vacuum as a sort of case study in creating “something from nothing”, because one of the properties of empty space is virtual particle and anti-particle pairs popping into existence for an incredibly brief time before annihilating each other. Empty space, as has often been said, is not “empty” at all but a churning maelstrom of vibrating fields and virtual particles.
He’s long been fond of saying that this model suggests that the universe arose literally from nothing, and that a quantum theory of gravity would support the idea of quantum fluctuations actually creating matter out of nothing. Indeed, this is exactly what is believed to happen at the event horizon of a black hole, where a briefly instantiated virtual particle is removed from the universe and the partner escapes as a real particle, a process known as Hawking radiation.
Krauss also believes in the probable but as yet unproven theory that the net energy of the universe is zero, supporting the idea that it came from nothing. Gravity is relevant here because in (some) cosmological models it’s considered to have negative energy – gravitational attraction removes the potential energy between two masses. Krauss’s (unproven) contention is that the total negative gravitational energy in the universe exactly balances the total mass-energy in everything else.
IANAP, but I think more accurately, at the moment of Creation the fundamental forces were not distinguishable and all had the same value. It doesn’t say anything about existing independently of the universe.
This is required in the way forces come about in the Standard Model, actually.
The fundamental forces come about via certain symmetries that are imposed. These symmetries have to do with ensuring that something analogous to rotations applied to the fields* in the theory throughout all of spacetime keep the theory unchanged. By simply requiring such a symmetry, the theory gains an interaction.
A symmetry most closely related to a simple rotational symmetry yields electromagnetism, although in the Standard Model this happens simultaneously with a slightly more mathematically complicated “rotation” that provides electromagnetism and the weak force in a unified way. One additional imposed symmetry generates the strong force.
This elegant origin of the fundamental forces also provides, among many other things, charge conservation. But you can’t assign the charges arbitrarily. If you did, the interplay of the symmetries would lead in general to non-physical results in certain calculations. These “anomalies” in a quantum field theory must always cancel out to zero have a consistent theory. This, in turn, requires an intrinsic relationship between the charges of all the fermions within a single “family”. Another way to say this: the very nature of the underlying “gauge” symmetries that lead to the presence of fundamental forces also leads to sum rules for how the charges of all the particles must relate to one another.
So, the quark and electron charges are not accidentally related.
That’s not to say there isn’t a deeper theory to be found or there isn’t applicability of the anthropic principle elsewhere (e.g., to why there are three families). But the relationship between quark and lepton charges is a-okay already.
* particles are represented by mathematical objects called fields in quantum field theory, which is the basis of the Standard Model
These are the symmetries from Noether’s theorem? I have a layman’s understanding of the conservation of linear momentum and angular momentum being associated with the symmetry of space, both linear and rotational. I know charge is conserved, but I wasn’t aware of what the associated symmetry is. It sounds a lot more complicated than something like the symmetry of space.