It isn’t, any more than one can describe the perihelion of Mercury solely by reference to GR and not QM or electromagnetic forces. The point is that GR explains certain things like black holes or the perihelion of Mercury which Newton couldn’t (and QM certainly couldn’t). You would simply have to ignore a vast number of features of the universe, just as if you tried to ignore QM.
A universe with no black holes does not change my everyday experience (get up, go to work, eat, sleep, etc), so I have no problem with a universe with no black holes.
Same goes for the perihelion of Mercury.
Of course, our universe has these things (black holes, etc), but the question in the OP had to do with whether there could be a universe that resulted in the same everyday experience for the residents of planet Earth.
Of course, if you require this hypothetical universe to exhibit all the behaviors of our universe, then I guess you can’t do without GR or QM (unless of course there are possible alternative theories to GR and QM that describe our universe, which I assume there aren’t any, at least yet)
Not really. If that happened on the macro level, then yes, it would be weird. Do you find it weird that what is “solid” to us is actually a collection of particles with more space between them than the particles themselves? It’s fascinating, but it’s not weird. Our human senses are not capable of discerning things that small. It just wasn’t necessary for us to survive. It doesn’t have anything to do with food or shelter. Why do people seem more able to accept that solid objects are not really solid, but balk at other details of quantum mechanics? Both are seemingly incongruous with our macro experience. Really, every new thing we learn seems “weird” at first. I’m sure people thought it weird that the Earth was round, or that it wasn’t the center of the universe, or that stars weren’t glowing spots affixed to rotating disks around the Earth.
By the way, my knowledge of qm is pretty shaky, but if I’m not mistaken, the “just because someone observes it” is one interpretation, but certainly not the definitive answer.
I don’t understand this question. You seem to be asking, “If the universe were different, would it be the same?” The obvious answer is no.
I understand that - my point was that the child-like description of the universe in terms of “everyday experience” doesn’t require GR or QM either. We can only say that if time and space were not part of the universe as in GR, or if particles were little snooker balls rather than the QM weirdoes we know them to be, this would simply represent a “DANGER: NO UNAUTHORISED ACCESS” sign barring more serious questions about this incredible universe we live in.
Yeah, it sure seems like the OP is asking that very question. But what he’s trying to get at, I think, is could the universe exist if Newtonian mechanics worked at all levels (micro, macro, and intergalactic). And that answer, too, is no per my earlier posts and those of others.
The idea that “black holes don’t affect me” is a fallacy. Leaving aside for the momonent that there is controversy over the existence of black holes, the very same laws that bring them about operate in the rest of the universe to make it what it is, even on our lonely planet.
This reminds me of a debate my gaming group had. The GM wanted to build his own custom universe for us to adventure in, and so we debated what the ground rules would be in order to determine what could and could not ever occur in that universe. After three weeks the fundamental laws of physics were still in committee so we gave up. But I recall some of what we could agree on:
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No Microscopic: The smallest quantum of space was the mote, roughly 50 microns. No microbes, no molecules, etc.
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No Outer Space: Your basic Ptolemic geocentric universe. The “world” was it, other than other-dimensional planes.
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No Hi-Tech Physics: not just that no one in this world knew how to make them, the laws of physics didn’t support them. Thus even a wizard could not build a nuclear reactor, a radio, or an x-ray machine. We allowed a sort of quasi-electromagnetism to allow for lightning, etc but it was more like a kind of magic.
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Since there were no atoms or molecules, no chemistry in the modern sense, only alchemy, another sort of magic. Biochemistry was replaced by vitalism (the “life force”)
In short, I think the OP is asking if something like this world could exist from a consistant rule of “how things work”, or if it would have to be haphazardly arbitrary.
That’s very close to what I’m asking, with “*the * universe” replaced by “*a * universe”.
Also, I don’t constrain this hypothetical universe from being only Newtonian, that is, it would be Newtonian + some other laws to make it all work out.
Also, I don’t constrain this hypothetical universe from being the same as our universe at all levels. That is, it is OK if at the subatomic level we observed a different set of particles and/or laws than we do in our current universe, as long as on the macro level the observed behavior was the same as our universe.
I assume you are referring to these posts:
What if these particles did not have the charges they do in our universe? What if they had no charge? What if this universe had different particles altogether?
Is it logically impossible to have E=mc^2 under another set of laws besides GR and QM?
Let me try to summarize a simple version of my question:
Let S be the set of laws that govern our universe, and let E be the set of things that are observable at the macro level in our current universe.
In our universe, S leads to E, which we can denote by “S => E”
Let S’ be the same as S except for the following
- the law that “nothing moves faster than the speed of light” is taken out
- some new laws are added and some existing laws are removed or modified in order to produce E
Can there exist such an S’, such that “S’ => E” ?
currently the universal speed limit is the speed of light. if there was no such speed limit, photons would accelerate to infinity and the momentum of them colliding with our planet would smash it into atoms. actually they might even get moving fast enough to split atoms, thus destroying everything in a nuclear explosion.
critics: i only believe light would accelerate infinitely because the speed of light is constant under all condition. if you shine a light behind you while moving near or at the speed of light, the light appears to move at the same speed of light to observers stationary relative to you. i interpret this as that light wants to go faster but can’t. (only had one college level physics course, so no confident in my conclusions
How do you know it doesn’t “want” to go slower?
ok sorry for my unscientific wording.
the speed of a wave depends on it’s medium. light therefore has a set speed limit based on it’s medium. i believe it is unique in that it sort of carries along it’s own medium in the form of the photon. according to my above post, when that person shined that light behind him while traveling at the speed of light, to the observer should have seen the light as stationary (thats standard newtonian physics). but that doesn’t happen. the person moving and the person standing still both see the light moving at the same speed (one must accept the extistence of two realities). the light would therefore have to be moving at twice the speed of light to reach the speed the observer sees. that says to me, that the speed of light based on it’s medium far exceeds that of the known speed of light. so i was wrong on saying light would accelerate infinitely. if someone actually knows physics and can point out why i’m wrong, or at least explain my concept better, please do so.
I’ve understood that at the beginning of time, there were ten universal constants fixed to specific values. One of those ten is the speed of light ©.
It is generally understood, and taken as a given, by my friends with degrees in advanced physics that if any of these constants were different, this universe would be a different place. A place most likely not hospitable to life as we know it.
Since c is one of those constants, any change to it would render the universe uninhabitable to humans. Removing it from the mix is a change.
This is basic parroting of advanced, obscure, and profound concepts that I’ve been told make perfect sense when you understand the mathematical terms in which they are described by people who know this as part of their live’s work. I believe them, because ya gotta take some things on trust.
I’m not sounding condescending to talk down to you, but because this is the only way I can keep it straight in my head.
Of course, Frederick Pohl explained it much better that I in his series on the Heechee.
This is all assuming the current laws stay the same.
If we have a function of ten variables (your “ten universal constants”), let’s call it
F(x1,x2,…,x10)
that represents the state of the universe today, then of course, if you change any of the inputs, you get a different output, and as mentioned before, most likely a *very * different and uninhabitable output.
But, there could be another function, of N variables, let’s call it
G(y1,y2,…,yN)
that represents the state of a universe with different laws. Can it be the case that:
G(y1,y2,…,yN) = F(x1,x2,…,x10) ?
The short answer: yes. There are an infinite number of possible laws of physics that describe our universe exactly as well as the currently accepted ones. The philosophers of science have pointed this out (much to the dismay of the “Platonic” physicists, who thought they were discovering the only “true” laws). For instance, assume that all things behave according to the normal laws of physics for everything within telescope sight, but just outside of that range, the laws are completely different. Unlikely? Perhaps, but not LOGICALLY impossible.
BTW, there’s a science fiction novel that’s set in a world where Aristotelian physics is true.
One of Arthur C. Clarke’s Three Laws* is The Universe is not only weirder than we imagine it’s weirder than we can imagine. I’m not sure if it’s elevant, but it needed saying.
I suspect that you can invent simpler universes. Have a look at A.K. Dewdney’s book The PLaniverse, which takes Abot’s “Flatland” to the nth degree – he and his many contributors (the book is essentially the result of years of newletter brainstorming on this idea) imagined what a real, 2-dimensional universe would be like. They created 2D analogues to 3D physics laws, biology, mechanics, etc. It’s fascinating read.
I have to admit that I’ve always been amazed that so many physical laws seemed so simple. What if energy equalled mas times velocity cubed, or to the 2.5 power? Or something weirder?
I suspect that you’d run into problems creating self-consistent universes if you chose your conditions at random, but that there are an infinite number o “possible” universes. (It could be that Dewdney’s “Planiverse” really isn’t self-conistent.) The problem is that (again, I suspect) that most aren’t terribly interesting, and don’t allow for sentient life.
- Laws always come in groups of three. This is known as CalMeacham’s Third Law.
Didn’t relativity theory do away with the idea that light travels through a medium? The medium was formerly called “the ether”, and that idea was dropped a long time ago, was it not? My understanding is that there are no absolute points of reference in the universe, so saying things like “observers stationary relative to you” is nonsensical from a relativity standpoint. Whether you are moving and I am standing still, or whether I am moving and you are standing still is something that is not possible to distinguish in space. Our motion is only relative to one another.
True, as long as we’re talking about empty space. But the speed of light does vary when it IS travelling in a medium, so it kind of depends on what that poster meant by “medium”. The famous Michelson-Morley experiment was what started the whole downfall of the ether hypothesis.
But the poster seems to be saying that light in a vacuum is somehow being prevented from travelling faster. I’ve never heard that before.
Why can’t we have a system of mathematics that precludes having irrational numbers? There is evidence that the Egyptians knew of iraationalnumbers, but feared them as being “evil”. Are most physical constants (C, planck’s constant, electron charge/mass ratio irrational?) 
Look out! It’s pi! Run for your lives… 
Well, the length of the diagonal of a square is irrational if the side of the square is rational. For example, if side = 1 then diagonal = sqrt(2). So, you can avoid irrationals as long as you can pretend that the diagonal of a square can’t be measured. Or the circumference of a circle. Or a whole host of other things.
Physical constants have to be measured, and they can only be measured to some limited accuracy. Any terminating decimal is rational, so you could say that all physical quantites are rational. This isn’t really correct, though: we only have a finite amount of information about the true value. (Knowing the true value would mean having an infinite amount of information. ) This finite amount of information can always be approximated by a rational number. (It could also be approximated by an irrational number, if you prefer. The speed of light, for example, could be written 2.12*sqrt(2)*10^8 m/s.)