We are all very likely doing it now with most of what we believe to be the laws of physics. While they may seem to reasonably explain the phenomena we have been able to observe that represents such an infinitesimal fraction of the universe that the margin for error is astronomical.
My partner is pursuing their PhD in Philosophy and studies history and phil of science and has dealt with this question a bit, so I’ll take a stab from that perspective.
My answer will rely on the possible worlds framework (a la Lewis) along with a tiny bit of knowledge about Newtonian mechanics.
Is it possible to imagine our world with different physics? Yes. Prior to discovering special relativity and quantum effects, we had newton’s Classical Mechanics, which was able to precisely and accurately describe and predict the movement of bodies in Euclidean space. So, if we can imagine our physics without the complications of curved space and quantum effects, we can imagine our world with an alternate physics that has been somewhat rigorously tested.
Additionally, we can easily imagine the world without the curvature of space and quantum effects (which should be clear by the fact that it’s not too long ago that we thought that was the best picture).
Classical Mechanics offers a working physics that just didn’t turn out to be correct in our (curvy) world. However, relying on the possible world’s framework, it would be easy to stipulate a possible world where Newtonian mechanics was true, or even a possible world where physics shifted from one set of laws to the other.
If we believe the evidence that physics could be otherwise, we might conclude that the laws of physics are relative to a world and a time (and, importantly to metaphysicians, not more fundamental than those two things).
I think a working physics lacking space-time or motion might be impossible to imagine.
Say a ship leaves Earth traveling half the speed of light, but it carries a communication device that can communicate with Earth “instantaneously” (i.e., faster than light). From Earth’s frame of reference, time on board the ship is slowed down by a factor of 0.866, while from the ship’s frame of reference, time on Earth is slowed down by the same factor. (This isn’t some trick of perception—the geometry of spacetime distorts in such a way as to make both these observations true simultaneously.)
Now suppose a year has passed on Earth, and we use the device to communicate with the ship ”instantaneously”. From Earth’s frame of reference, the ship has currently experienced only 316 days of elapsed time, so that’s when they receive the signal according to their clock. But from their frame of reference, Earth at that point has only experienced 274 days of elapsed time—so when they send their “instantaneous” reply, it arrives on Earth three months before the original signal was sent.
From Earth’s frame of reference, time on board the ship is slowed down by a factor of 0.866, while from the ship’s frame of reference, time on Earth is slowed down by the same factor
Why is time on earth slowed down from the ship’s perspective? Shouldn’t it be faster? Like if earth perceives that the time on the ship is passing slower shouldn’t the people on the ship perceive the time on earth as passing faster to compensate?
Also, I have quite a hard time understanding how time exactly slows down. Is it sort of as though we adjusted the time step duration (tickrate, more precisely) of a physics simulation in an area (making everything happen slower/faster there in relation with the rest, where the original timestep is kept)? (Without losing precision and all those problems that occur in a simulation normally) Or is this analogy flawed and that is why I’m not getting it?
Why is time on earth slowed down from the ship’s perspective? Shouldn’t it be faster?
According to special relativity, all non-accelerating frames of reference are equally valid, so the observations are symmetric: both Earth and the ship see the other moving away at 0.5c, so they both see the other slow down.
Now it’s true that if the ship turned around and returned to earth at 0.5c, it would be the ship’s clock that was behind earth’s, and not the other way around—but that’s because, when the ship turns around, it accelerates, and while it does so the whole non-accelerating frame of reference thing goes out the window. After it finishes turning around, the point in earth’s timeline the ship judges to be simultaneous with its own will have jumped into the future—so that even though it observes earth-time moving slower than its own during both the outbound and return trips, the time jump as it turns around will more than compensate.
Okay. Thank you! This explanation made it click for me (now I think I get the original example too). Here the real cause of the violation is the instant communication, isn’t it? If the communication was done via radiowaves (which as far as I know also travel at the speed of light) it would not be violated, because of the time it takes for the information to arrive from the Earth to the spaceship and back, is that correct? Is this why (as I have read/heard on several occasions) the upper bound for the speed of information is also the speed of light?
Has anyone actually proven no violation of causality? Wikipedia seemed to suggest that it’s not physically impossible to have a wormhole, take one of the ends on a round trip so that it doesn’t age as much, and you’d be left with a situation where you can go in one end and come out in the past.
No—“no violation of causality” isn’t a physical law that can be formulated, much less proven. It’s just our intuitive feeling that anything physically possible should also be comprehensible.
This argument, as far as I know, relies on the nature of time dilation. You see as your velocity increases closer and closer to the speed of light, time itself begins to slow down. This is not an analogy or some fancy math trick, this is a real thing you can measure in the lab. As you get closer and closer to the speed of light time slows more and more. Such that as you reach the speed of light (again this is physically impossible at least for anything with mass) you can think of time as stopping. So for light or anything that moves at the speed of light they’re kind of isn’t such a thing as time, but I digress.
So (again even though it’s actually impossible), what happens as you start to go faster than light? Does this trend continue? If it does that would mean that time starts to reverse. And once you see that faster than light travel might imply time reversal, it should be easier to understand how this would violate causality. Because how do you get event A caused by event B when event B was before even A?
iirc the only method of faster than light travel that doesn’t violate laws of physics involves warping spacetime. We can now detect ripples in spacetime, and scientists postulate that in the far future it might be possible to manipulate spacetime by warping it with technology not currently in existence.
Of course you could argue this method isn’t really faster than light travel, since you’re actually bending the distance between you and the destination.
I don’t have the study to back this up, but personally for me it has a lot to do with how heavy I am. When I’ve been thinner I’ve been much more tolerant of humidity and heat.
It’s not some force keeping them the same, it’s no force changes the speed of the moon. From my limited understanding the moon was created when a smaller planet crashed into the earth:
They both got the same momentum, therefor they started rotating at the same speed, once per day.
There is nothing out there which would be able to change the speed of the rotation of the moon. There is also nothing which would change the speed of the rotation of the earth. Therefor they keep spinning at the same speed.
Other people have explained it, and the same thing happens with other moons in the solar system, including some orbiting gas giants where your explanation couldn’t have worked.
The Earth’s gravitational field elongates the moon slightly, and an elongated satellite tends more to stabilize its rotation with the longer diameter fixed to point at the center of its orbit.
Quite frankly, all of them, as in literally all of the levels. e.g., viruses are not considered "alive" in the classic sense, but they sense things sometimes & change their behavior accordingly. A single protein can do it too, like in mad cow disease / scrappy (called "prions"). Even a tiny snippet of DNA can make logical circuits akin to computer ones, implementing AND, OR, XOR, NOR, operations etc., plus feed-forward loops (& feed-backwards, and all other sorts).
Possibly even subatomic particles, and maybe even quarks (or strings?) do the same - e.g. the Heisenberg Uncertainty Principle where you start to interact with something and then that changes it already so that you cannot measure other aspects of its previous "natural state". Okay that's not so much a "decision" as a "reaction" - but as you are questioning, what really distinguishes the two, REALLY?
Bacteria can sense a molecule (like sugar), literally start growing a tail (no joke!), and then swim towards it. All entirely chemically, and we have the technology to literally just kinda 3-D print all that at the molecular level (it takes an existing flagellum but once that is added to the mix, it can grow just like a crystal, by extension / copying of the old pattern).
Most of what we considered to have made humans "special" in the word turned out to be false - e.g. chimps & gorillas can "talk" (it's hard for their throats to make our kinds of sounds, but given the right apparatus they can get the job done), and think in abstract terms, and do math, and all kinds of things. Of course, humans ARE special - we are the only things on planet earth that if aliens came, could attempt to nuke them in orbit, and we literally light up the night sky! But there's a whole continuum of "dust" that share a lot of properties with us, in various ways. I'm not sure if animals have the same kind of subconscious vs. conscious interplay going on as we do, but if you have a pet and stare at it trying to work through a decision, you KNOW that it's doing the same as us, at a fundamental level. And then each time you go a level deeper, the similarities kinda never end...
Such questions may never even find answers, at least in our lifetimes, but it sure does seem worthwhile to ask anyway... it sharpens us, so keep digging!:-)
You've stumbled upon the basis of the debate between free will and determinism. imo, we are merely under the illusion that we're making our own choices. The universe is one infinitely complex system of falling dominoes, with each choice and action just being the result of the parameters set by the ones preceding it. We are all made up of the same basic building blocks, and are thus just subatomic systems obeying the laws of thermodynamics... it just happens to be the case that when a system reaches a certain level of complexity, it is able to think about itself - we are quite literally the universe experiencing its own existence.
Why is this? I don't know. Nobody knows. Consciousness and 'the ability to experience' is one of the most elusive and complex questions facing science and philosophy today. It's my personal belief that there is certainly 'something' more to this whole cosmic experience, but I'm not convinced by religion's answers and believe 'it' to be something so vastly incomprehensible and foreign, we'd never understand it even if the mystery were revealed to us. It isn't something I like to think about too deeply, because unfortunately, it opens up an infinite regress of questions we will likely never have the answers to.
Abandon the philosopical concept of an independent thinking mind capable of evaluating something by itself.
“Decisions” and “Thoughts” don’t exist without the environment, as they’re a succession of neuronal activation cascades in response to the current state of all stimulus, the previous connections formed in your brain, and reinforced patterns.
Leave a human being in an empty void and their thoughts will be built by severely boosting sensitivity and then responding to random sensory noise. Sever all sensory connections and the mind shuts down.
Frankly, the decisions that we make are chemical reactions. The difference is in the complexity of the decisions that we can make. At that point, though, in order to answer your question, we would need to argue about what one would consider to be a decision that’s complex enough and a decision that’s not complex enough, and that leans much more into philosophy and ethics rather than science.
I can only tell you that, from a mechanistic point of view, there’s not really much distinguishing our decision making process from, say, the decision making of a flatworm
All the large moons in the solar system are tidally locked to their planet!
Pluto and Charon are tidally locked to each other!
The earth would eventually be tidally locked to the moon too, but because it’s happening so slowly, it wouldn’t happen before the sun turns into a red giant and engulf both!
There is such a huge difference in the masses of the earth and moon that although the moon is slowing the rotation of the earth, the earth’s rotation is also speeding up the moon’s orbit. The faster orbit is causing the moon to move farther away from the earth.
So, the purveyor of the electromagnetic force is the photon, as in visible light and radiation. If you look into it you find talk of “virtual photons” being the purveyors of magnetic force, but it seems they are more of a mathematical construct, and if you read enough about it, it becomes clear that it’s a whole lot of technical language that boils down to, “we dunno”.
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