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A delightful quirk of relativity theory

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Re: A delightful quirk of relativity theory

#181

Post by SuoDuanDao »

JackFr wrote: post #169
SuoDuanDao wrote: post #154

Earlier quoted context omitted.

I find the most satisfying version of compatibilism one where an agent is mostly determined by 'state' (genes/experiences etc), but the subjective experience of expending mental effort (e.g. when overcoming an addiction) is the agent nudging the wave function collapse this way or that. Add in the ability to influence future 'states' and one has a model much more consistent with the subjective experience of making dif…

Or you can just accept that reductive materialism is not an adequate description of the world.

Oh I accept that, but I'm also wary of theories that seem to handwave material reality. I've found Dione Fortune's writings the most useful in that regard, though she can be... obscure. Quite influential all the same.

Re: A delightful quirk of relativity theory

#182

Post by naasking »

vidarh wrote: post #101
kybernetikos wrote: post #45

Earlier quoted context omitted.

You've put the dilemma nicely - it can't be both 'free' and 'your will' by your definitions (well, without admitting supernatural beings that can affect and be affected by the natural world, but are not part of it). Personally I'm happy with other definitions, not because I feel I'm doing mental gymnastics, but because the version you give is clearly not what normal people mean by it when they refer to it. It might w…

> Personally I'm happy with other definitions, not because I feel I'm doing mental gymnastics, but because the version you give is clearly not what normal people mean by it when they refer to it. It might well be related to what philosophers argue about, but normal people who offer you a 'free choice' or who say that you did something 'of your own free will' do not mean anything like 'your choice was not a function o…

> E.g. if you genuinely believe the notion that we have free will is nonsense (and I do), then the logical extension is to be very uncomfortable with the notion of e.g. prison used for vengeance or anything at all other than to the bare minimal extent required to protect others, because the logical conclusion of thinking people don't have agency is that there was no way other than other external stimuli in their lives that they could have come out making other decisions.

I think this lacks imagination for human cruelty. If they had no free choice but to steal my things, then I guess I don't have any free choice but to torture them in revenge. Hard determinism does not erase the possibility of punishment.

Re: A delightful quirk of relativity theory

#183

Post by goblin89 »

awb wrote: post #88
Jeff_Brown wrote: post #86

Earlier quoted context omitted.

The reason the scenario posits an invasion from so far away is that that's about how much distance it takes for a small speed difference here to translate into a day long time difference there.

You could imagine an event happening a day later from a traveling car, but that’s about it. Two people can’t actually observe an event a day later from the same reference point (Earth), and naturally the event occurs at a singular time at Andromeda’s reference point. Same with any point between Earth and Andromeda. So, if you can’t observe it at different times from the same reference point did it actually happen at…

A philosophical idea may not have meaningful implications within the scope of physics, but that doesn’t make it useless.

Rietdijk–Putnam argument, for example, appears to sort of elevate the idea of differing planes of simultaneity, taken from special relativity, to an idea of a four-dimensional universe. It’s a curious thought experiment and I wonder how it reconciles with a model where the universe is considered to be 4D with the fourth dimension being time. My intuition doesn’t work all that well beyond three dimension so I can’t tell if those are essentially the same or not.

It’s not falsifiable, but neither is string theory.

Re: A delightful quirk of relativity theory

#184

Post by danbruc »

awb wrote: post #164
danbruc wrote: post #100

Earlier quoted context omitted.

However, we do know from Quantum Mechanics that the universe is probabilistic and not deterministic That is not true, quantum mechanics - more specifically the Schrödinger equation - is deterministic. What is not deterministic is the wave function collapse but that is also incompatible with the Schrödinger equation because it implies non-unitary evolution of the wave function. And we have - as far as I know - no real…

From the article: > One of the key implications of the Heisenberg uncertainty principle is that it highlights the probabilistic nature of the universe

The article is wrong there. I can not provide a good source so I will just point you to this StackExchange question [1].

[1] https://physics.stackexchange.com/questions/63811/is-the-uni...

Re: A delightful quirk of relativity theory

#185

Post by guelo »

danbruc wrote: post #42
irthomasthomas wrote: post #21

This would be more fun in a blog post. Twitter is a fucking horrible format for a complex analysis of special relativity. That aside, my favourite quirk from relativity is this: "The more you move in space, the less you move in time." Like relativity in general, it sounds simple enough, but it's consequences are profoundly shocking. (That is, if you take the time to understand it, and don't leap to the conclusion tha…

Rescuing free-will from the jaws of spacetime would be cool! Free will does not exist. It is logically inconsistent. Either your choice is some function of your current state and the environment you are in, then the choice is not free, or it is independent of your current state and the environment you are in, then it is not your choice in any meaningful way, it is just the result of a coin flip. You can do some menta…

I think your argument against free will can be boiled down to the question of if true RNGs exist. Even leaving out quantum probability, we can easily consider systems of such high entropy that a computer the size of the universe would be unable to deterministically calculate the results.

Re: A delightful quirk of relativity theory

#186

Post by awb »

Ma8ee wrote: post #23
irthomasthomas wrote: post #21

This would be more fun in a blog post. Twitter is a fucking horrible format for a complex analysis of special relativity. That aside, my favourite quirk from relativity is this: "The more you move in space, the less you move in time." Like relativity in general, it sounds simple enough, but it's consequences are profoundly shocking. (That is, if you take the time to understand it, and don't leap to the conclusion tha…

Isn't the whole point that talking about "the present moment" about something very far away isn't particularly meaningful when simultaneity for spatially separated events depends on the observer?

Correct, check the criticisms on the Wikipedia page:

https://en.m.wikipedia.org/wiki/Rietdijk%E2%80%93Putnam_argu...

Re: A delightful quirk of relativity theory

#187

Post by Diggsey »

awb wrote: post #61
irthomasthomas wrote: post #21

This would be more fun in a blog post. Twitter is a fucking horrible format for a complex analysis of special relativity. That aside, my favourite quirk from relativity is this: "The more you move in space, the less you move in time." Like relativity in general, it sounds simple enough, but it's consequences are profoundly shocking. (That is, if you take the time to understand it, and don't leap to the conclusion tha…

> Take the case of two people on Earth, one stationary and one travelling past in a car. They each have a different reference frame, and a different set events which make up their present. Now imagine that there is an alien government in Andromeda debating a possible invasion of Earth. In the reference frame of the person on Earth who is moving, the debate is still going on. But, in the reference frame of the station…

Actually no, the parent comment is correct:

When you undergo an acceleration, it corresponds to a hyperbolic rotation of the spacetime around you (from your frame of reference). When the acceleration is small, the rotation is also very, very small; however at very large distances, even a small rotation can have a large effect.

In the example, that "large effect" is the alien debate moving in time forward or backwards a day (again, from the accelerated reference frame).

This has nothing to do with the observation delay, it's just an artefact of what it means for two far apart events to happen "simultaneously": simultaneity is a relative property, so two things that happen simultaneously in one reference frame might not happen simultaneously in another.

The reason this doesn't introduce a paradox is because without a specific reference frame, events only have a partial order: when you compare two events, there are three possible results:

1) Event A is in the past light-cone of event B.

2) Event B is in the past light-cone of event A.

3) Neither event is in the past light-cone of the other.

For 1+2 this means that the time between the events is greater than the distance between the events, whereas for 3 it means the reverse. For 1+2, the ordering of the events is the same for any reference frame. For 3, there will always be some frame of reference where both events appear to happen at exactly the same time, so nothing can be said about their order without choosing a reference frame.

Re: A delightful quirk of relativity theory

#188

Post by dalmo3 »

vidarh wrote: post #130
kybernetikos wrote: post #127

Earlier quoted context omitted.

I think free will is the feeling of being a choice making agent in the absence of unreasonable external constraints. This isn't original or unique with me, and I've held this view for quite a large number of years (e.g. this comment from 6 years ago: https://news.ycombinator.com/item?id=11740316 ). It fits pretty well with what people mean when they say 'free will' or 'free choice' in normal every day life (i.e. if y…

Try probing what people think having free will actually means, and you'll quickly see that people tend to react very strongly if you suggest that they don't have some vague undefined ability to take actions that are not defined merely by the state of their brains and inputs. To me what you describe does not at all match what I've observed people try to defend as free will whenever you peer beneath the vague veneer of…

> ability to take actions that are not defined merely by the state of their brains and inputs.

How would one prove/falsify that one's actions are merely a function of their brain state and inputs?

Even assuming we have a perfect mapping of the brain and perfect measurement of all neural action, experiments still happen over time and the act of observing changes the observed, so you'd never have repeatability.

It seems to me that determinism is as unscientific as the soul hypothesis.

Re: A delightful quirk of relativity theory

#189

Post by dalmo3 »

awb wrote: post #75
antattack wrote: post #62

Earlier quoted context omitted.

If your definition of free will existed, how would you prove it?

Exactly. Free will (or lack thereof) is an untestable theory, better categorized as a thought experiment or philosophical debate.

That's how I see it too.

Determinism for human action is very popular among science enthusiasts because we've decided that determinism elsewhere in science is true, and since our brains is part of the universe then it must also be deterministic.

But we only perceive determinism insofar as we only measure what we're able to measure. Then you arrive at quantum probabilities, and it seems to me the multiverse theory is as scientific as believing quantum particles have free will.

Re: A delightful quirk of relativity theory

#190

Post by [deleted] »

penteract wrote: post #156
Retric wrote: post #94

Earlier quoted context omitted.

That’s not how it works. But even beyond that you have the math wrong. Andromeda galaxy is only 2.5 million light-years from Earth. To get a 1 day difference in time dilation across 2.5 million years would take 1 in 913 million difference which someone traveling at even 100MPH (45m/s) isn’t going to see. (1 - (45^2/((3x10^8)^2))^0.5 simply isn’t enough.

I did the calculations from https://en.wikipedia.org/wiki/Special_relativity#Lorentz_tra... and it comes to ~0.25 years if the person in the car is moving towards Andromeda at 30m/s. γ is indeed very close to 1, so the humans' watches would still agree closely after 2.5 million years, but the humans would be a quarter of a light year apart at that point, so they need to disagree about something to get the same observ…

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