Forgive my amateurism here, but I keep reading that we don’t yet have an explanation for the unidirectionality of time, increasing entropy, etc. Doesn’t that imply that causality could work differently in different universes?
Here’s the problem: the definition of magic. My definition is that Magic is something which defies the laws of the universe in which it is invoked. So if you have a universe in which light travels at 56,000 miles a second, which appears to defy our current norm, it would be normal for that other universe.
It would be interesting to see an “alternate universe” in which much Science as we know it could not be applied (and yet was still more or less consistent with known physical laws as we believe them to hold).
I’m talking about a place where no experiment would be repeatable due to wildly improbable (by our standards) events interfering. Every event is unique and local. I think for it to be still consistent and livable there might have to be some observable phenomena, just no way to develop a method that unifies them into laws.
The more I think about, the less likely it seems to be that anything would be in it except chaos.
The problem with those ‘infinitely improbable’ universes where, say, the second law of thermodynamics (entropy always increases) just happens to be violated (which certainly exist in a setting where you have a continuous infinity of universes), is that if you found yourself within them, and in the past, your magic worked based upon this improbability, the next time you try to use it, it will certainly fail. And there are no universes in which the second law is systematically violated; it’s really just a statement about probability, basically just the assertion that more probable configurations occur more often.
As for other violations of the laws mentioned in the OP, at least according to current physical theory, other than the ‘unlikely things sometimes do happen’ universes, they’re all true for other universes, as well – in particular, any universe generated through chaotic inflation will obey general relativity in the large scale limit, as does anything within the landscape of string theory (though I guess that it’s possible that there are pathological universes that don’t have a large scale limit – in fact, I believe most string theories don’t readily admit a naive geometrical interpretation --, but at some point it becomes a bit of a quibble what you want to call ‘universe’), so we’ll have local conservation of energy, causality, etc. All of those universes (and Everettian worlds of course as well) also obey quantum theory, so you’ll also have things like Heisenberg uncertainty, a least action principle, etc., which also incorporates much of what the OP was asking for.
So I guess it’s not a priori impossible that there are universes out there that ‘magically’ differ from ours, but there’s none in our current physical theories – and how could there be? If we had a theory that supposedly explained how our universe works which admitted many ‘magical’ solutions besides the physical ones, then it would in fact not have any explanatory power. We’ve got enough on our hands with the rather overwhelming richness already postulated by existing theories, which just concern variations in physical content…
The OP usage for “magic” is key here. I think it is unreasonably bold to rule out real, physical, natural phenomena that violate the laws cited by the OP, because we may expect that at least some of these laws will be exposed as incomplete or inaccurate. When my grandfather was 20, Einsteinian relativity and quantum mechanics didn’t exist, and the Milky Way was the entire universe according to some mainstream scientists. Hell, I can remember when Mars had canals that got more or less green with the passing of the wet and dry seasons as vegetation flourished and withered.
It seems to me that modern scientific thought leaves plenty of wiggle room for universes in which the OP’s definition of magic is realized. The papers of physicist Max Tegmark at the University of Pennsylvania are a good example, and one appeared in Scientific American just a few years back.
I think there is nothing real that is supernatural, taking “supernatural” to mean “above nature” or “outside of nature”. This would of course preclude things that are supernatural and also manipulated by people. But this ironclad rule would be based on the thoroughness of nature and the wrongness of religion, and not on the final accuracy of our current understanding of how nature works.
This is actually irrelevant, though. Another universe may have totally different laws from us. Moreover, there’s ultimately nothing which prevents, in as much as we know, events in one universe from causing reactions in another. That is, there may be universes which can alkter others. Moreover, there ay be universes which we could not even interact with, much less perceive or notice.
*Depending on your view of some physics, this is indeed the case, at lrast with regard to very small folds in space, which can affect us in awesoemly limited ways, but which we can hardkly even imagine. We can’t really prove they exist, but the concept of many-dimensional (there’s arguements over how many) energy is well-known in physics. Don’t ask me to explain it.
As a practical matter, we are unlikely to totally turn over our conception of the laws of physics universe. It is possible, just not likely.
I would suggest you are moving the goalposts. If we find another universe which ahs its own rules, would that then be instantly added to your definition of “nature”. If there is, in fact, a supra-dimensional order, woudl that suddenly be the “real” nature?
No, it would by definition be supernatural, whether or not you call it religious in any sense. It also might be utterly incomprehensible to us.
Well, in the D&D “universe” (and many other similar universes), arcane magic (the kind used by wizards and sorcerers) is itself a “force of nature” that exists alongside all the others, with its own specific rules that can be manipulated by anybody clever enough to understand those rules. It’s essentially its own branch of science. Divine “magic” acts, OTOH, despite being called “spells”, are basically miracles performed by a deity at the request of a cleric/priest. Deities having the ability to violate natural laws at will, and to allow their priests to channel that ability.
The difference between the two types (in D&D anyway) is illustrated in the way that even the most powerful arcane spellcasters know only a small subset of all the possible arcane spells and can only cast spells from that subset, while the most powerful divine spellcasters have access to every possible divine “spell” and merely have to pray to their deity and request the specific ones they think they might need each day.
It would almost be funny how many people are ignoring the definitions set out in the OP, if lack of reading comprehension wasn’t such a peeve of mine. To reiterate, for the purposes of this thread and my argument:
Now, to expand on Chronos’ answer: The parameters that are hypothesized to vary among different inflationary bubbles or regions in the “multiverse” are things like the coupling constants of the forces, the masses of the particles, parameters that govern the oscillations between particle states, possibly the number of large and small dimensions, and constants governing the composition of the universe, like the ratios of regular matter, dark matter, and dark energy. None of those parameters have any say on the fundamental relationships that comprise the things that Skald has listed. (By the way, Skald, the thing you may have left out is the Uncertainty Principle.)
To give a simple example: Newton’s second law is F = ma. I can fiddle with the mass all I want, but it doesn’t change the fact that acceleration is equal to force divided by mass. I can make the fundamental forces different strengths, I could increase gravity, or decrease the strong force, and this would fundamentally change the contents of the universe (i.e. change the strong force enough and you can’t have atoms as we know them), but it would not change the basic patterns governing the flow and exchange of mass, energy, and information.
True, but the way I understand the OP, he was asking for possible alternate universes according to current physical theory; that it’s always possible that we have everything wrong is really a bit of an empty statement, since from there, of course it follows that anything goes in other universes. And in current physical theory, there are definite limits on the kinds of universes admissible – take, for instance, the string landscape, which can be thought of as providing a parameter space for possible universes, provided strings pose a valid fundamental theory. Those universes might look very different from ours, having completely different matter and force content (well, they’ll all have gravity), but they’ll all be universes described by string theory – so if string theory respects, say, conservation of energy (which I’d expect is a bit of a thorny issue, which it already is in general relativity), all of those universes will respect it, as well. And there definitely won’t be any second law violation (other than on a probabilistic basis). The same goes for universes generated by eternal inflation; and even in Tegmark’s proposal, I think there’s a good case to be made that even his level IV multiverse, where different regions are described by different mathematical structures, should obey the second law at the very least.
Why would one consider them separate universes if they can interact with one another?
Not really sure what this is supposed to mean. Many-dimensional energy isn’t something I ever encountered before; string theory (among others) proposes that spacetime has more than the macroscopically observed 3+1 dimensions, but this isn’t really anything mystical, it’s just that the equations don’t work in lower dimensions (there’s an article that’s either just come out or about to come out in Scientific American by John Baez, who together with John Huerta has done some fascinating work on why this is so – or rather, why supersymmetry, an integral part of superstring theory, only works in certain dimensions; the ten dimensional case is then picked out by quantization considerations). Since spacetime doesn’t look ten dimensional, it’s then proposed to ‘compactify’ the excess dimensions such that they are not ordinarily visible – but in principle, with high enough energies, they are readily observable. However, I gather that the more modern perspective is to not regard the extra ‘dimensions’ as being something very much like our familiar three space dimensions at all, but rather a more abstract kind of degree of freedom which may not have any nice geometrical explanation.
Quoth smiling bandit:
Posited, certainly. Scientists posit all kinds of crazy things, especially when we’re drunk, high, or sleep-deprived. But none of those things has ever been posited in any theory. Such things, when they crop up, are always in mere models, and usually toy models at that.
Because they may not in the ordinary course of events. It may take some unusual preparation to connect them, or it may be possible from only one end. Given a sufficiently large number of universes, it is likely that some would
Also, to explain something I said before (which you didnt’ comment on but which may help make sense of things): remember that according to our best theories, suddenly and for no explicable reason, our universe exploded into existence. That strongly implies something out there spawned our universe. You don’t have to believe it to be an intelligence, per se. But some rule or law or power made iot possible. (There is a proposal that it occurred within our own universe, and that our universe created itself I find it improbably, and not well explained. It’s basically there as a wild guess, and if true, implies that we could create possibly-infinite numbers of universes along the way).
There’s some thought that in order to explain subatomic (well, sub-sub atomic) particles, we may have to resort to between 6 and 21 dimensions (the highest and lowest I’ve heard proposed). And no, this isn’t this “mystical” in any sense. It’s just that another universe may exist, in as much as we do, living lives totally irrelevant to ours. And they may use utterly different physical laws. The laws of our universe aren’t anything special as far as we know. They simply are. The laws “elsewhere” could be utterly arbitrary from our perspective.
That doesn’t mean it would be “magic” to them. It would be as natural as breathing - as natural as humans throwing rocks.
So you claim it does not exist?
Right now, we have good reason to think other universes probably do exist. We may never be able to interact with them in any sense. In fact, one minimal result of the many-worlds thesis is that any possible world must exist - including any possible world which support the many worlds thesis. And that includes a lot more than our physics.
However, as pointed out, we have in this universe ample reason to believe that the laws we know of not only did not always apply, but could have been different.
Scientists don’t waste a lot of time on this, rightly, because it cannot be proven or proven false. By definition, it’s unknowable. We can’t interact or perceive the other. But that does not mean it does not exist. We can logically deduce its existence.
I’m not sure what you mean by “it”, here. Some theories do suggest the existence of other worlds, which might reasonably have different values for some of the fundamental constants. No actual theory suggests the existence of other worlds where, say, the laws of thermodynamics or Lorentz-group symmetry do not hold. We can construct models which describe such worlds, but they’re only models, not theories.
Strictly speaking, no theories can describe any other world whatsoever, because we can’t theorize effectively about something we have no direct evidence. But we can inductively reason that because…
(A) Other universe are possible because ours is possible.
and
(B) We have no knowledge of any intrinsic rule which requires them to have natural law similar to ours.
we reach
(C) Other universes likely do exist.
We can break (A) down by saying that we believe our universe more or less just happened, and it is reasonable to think that other universes can also happen. Inded, there is almost certainly reality “above” our own, which provided the rules which enabled our existence.
We can break (B) down by noting that the natural law for this universe was not always the same, and that in as much as we know the phsyics we have were created randomly.
In short, I find it extremely probable that other unvierse exist, extremely improbable that we could ever know anything about them, and extremely probable that some (many? Infinite nubers?) have laws we can hardly imagine.
Not one theory proposes this. The best of our theories describe the evolution of the universe from when it was about a Planck time old, and do so very thoroughly; for times previous to this, we would need a theory of quantum gravity, which we simply don’t have (in any agreed upon form). Nevertheless, more speculative attempts, such as loop quantum cosmology, are able to give a description of this regime – in this particular case, gravity becomes repulsive at high enough energies/small enough length scales, leading to a ‘big bounce’ scenario --, but there’s neither enough evidence to decide which one is true, nor are the models worked out enough to be fully predictive.
The extra dimensions postulated by superstring theory don’t have anything to do with ‘another universe’; they’re a characteristic of our universe, just as much as length, width, and height are.
Not if the other universe is described by the same ‘master theory’, i.e. is for instance born out of the string landscape, which is really the only case we can say anything about.
The many worlds of the Everett interpretation of quantum mechanics, which I presume you refer to, all trivially follow the same rules of quantum mechanics as our universe does.
When was it different?
Aren’t there subatomic particles that seem to not be subject to causality? If that were the case, a universe consisting of only those particles wouldn’t have the causality principle.
You can write down a theory involving tachyons, which are formally something like ‘faster than light particles’, and faster than light influences violate causality, but a) those theories have some internal problems that generally lead to them being considered unphysical, and b) even so, you can’t use tachyons to send information faster than light (which would be required for causality violation), since you either get localizable disturbances in the tachyon field, which however then turn out to actually propagate slower than light, or you get something which propagates faster than light, which then turns out not to be localizable.
Other than those, all particles in quantum field theories live in the smaller-or-equal-to-c velocity sector of special relativity, where everything is nicely causal.
Quick hi from Earth #43. We got Science, we got Tasty Low-Carb Pizza, but, sorry, no Magic.
We got Causality. Plain old vanilla “Hit the ball, ball moves.” Fairly boring. Unidirectionality of time, increasing entropy, conservation of energy, yada yada… Sure, we got God here, too (but since he created the world, and its rules, He doesn’t screw around with parlor tricks). Oh, and we do have Kurt Cobain (but as part of his therapy he started writing commercial jingles).
By the way, your John Mace IS kind of dickish.
Disappointing.
Here he’s a thoughtful, open-minded commentator that listens to people and learns from them. There’s a rumor he might be tapped for Secretary of the Internet under President Zotti.