I've been following this discussion closely because I work in adjacent areas and have dipped into Coq and Agda. Now that I see it on hackernews and all sorts of comments speculating on how this is cancel culture and English-centric chauvinism I'm really disappointed. Sometimes you lack the social context to evaluate the merits of a discussion so you default to your image of the most plausible motivation and it says a lot in this case. A popular idea here is the "gellman amnesia effect", yes? Well I'm definitely not going to forget this in the broader context every time a post comes around baiting culture war rhetoric.
Unfortunately some women actually in the Coq community discussing this on Twitter noticed they were getting all of a sudden a lot more engagement with concern trolls around the time this submission gained traction. "intellectual curiosity" indeed. I hope its worth it, this place existing. I think I can find a replacement though so I'm logging off indefinitely.
What people say are their values and the values revealed by their actions can be different. Moreover one can express certain values in pursuit of goals that are incompatible with those values. This is styled hypocrisy and the bourgeoisie such as Thiel are very used to this.
Almost by definition society is the negotiation of our behavior toward each other because otherwise we would impinge on each others' freedom to act as we please in intolerable ways.
Perhaps you think that is a bad thing and to be honest i wouldn't blame you if you decided to ignore all laws and norms of society and behaved like a feral animal towards others. I just don't think you would get very far before you're put in a cage or gunned down.
Do you have legal rights or restrictions outside of society? Living in society inherently means having a discussion of enforced boundaries and imposed burdens.
In case you did not realize it: yes, in times of crisis governments can take away your rights. If those governments are democratically chosen then that's society taking away your rights. If they are dictatorships then that's a different matter, but that does not seem to be the case here.
This is way too absolute. "Democratically" picked representatives can just as well exert force not in alignment with what the society of said democracy would want when the question would be voiced directly rather than indirectly taken care of. Or are we really going to be so naïve to believe representatives will stand behind every single one of their words their entire term, and pretend they don't pull stunts to bait & switch potential voters for a win rather than a loss?
Democracy isn't perfect. But that we already know. It has nothing to do with the subject though, so as far as I'm concerned you're off topic, I tried very hard to show why a democracy may sometimes opt to limit the rights of its denizens, and one of the times when this is legitimate is during times of crisis or when the lives and or well-being of its citizens are at stake.
This may not be absolute enough for you but then you'd have to cast the laws in stone without the ability to ever change them and then it ceases to be a democracy.
The only two true rights are freedom and property.
You are born with free will, and you can do whatever you want, unless someone actively prevents you from doing it.
You are born with your body, which is yours, your original property, and is the source of all other property you may gain through your life by using your body (including your brain) as a tool to obtain it.
Those two rights are yours by origin, you were born with them, society doesn't need to give them to you, all the other rights are just corollaries of those two, and whatever infringes these rights are not true rights.
The right to life is derived from the respect others should have for your will to live, and the fact that they shouldn't damage your body (property).
In your comment you are painfully confusing right with a warranty. There is no warranty for anything. Even in the midst of civilized society there is no warranty you'll live, what you do have is the warranty that society will do its best effort to punish those who killed you.
You never had a right to eat your neighbours. Neither Homo sapiens nor other animals.
Your human rights are yours because you are human, they don't derive from any social contract, they are not granted by society. Society can only respect them or violate them, not give them to you.
You might wonder what are your human rights then? The answer is easy, is what you were born with: Freedom and Property.
Freedom because you have a will, and you can do what you want if no-one hinders you. Property because you were born with your body, it's your to do with it as you please.
Any other so-called rights that violate these two fundamental rights are false rights. The "right to eat your neighbour" could never be a real right because it presupposes that you can eat them no matter what, you wouldn't need their consent in order for you to eat them and that would violate their freedom.
Actually, there is a bunch of other false rights that are in the same line as your "right to eat your neighbours": the right to food, the right to health-care, the right to housing, the right to anything that requires someone else's labor. Saying that such things are a right imply that someone else has to labor in order to grant said false rights to you. The "has to" part violates someone's freedom. We have a name for that: slavery.
I have trouble believing that you truly believe this, but in case you are not trolling:
You are not born with any rights. Rights are social constructs, always were, always will.
You decide that your right to roam the world is more important that the right of ants to live (you squash them when you walk). Some buddhist think otherwise and sweep in front of themselves before moving somewhere where ants might be.
Your distinction of “what requires other beings’ labor” will take you no where, almost all your actions will impact others. Do you think killing yourself is misusing your parents’ labor? No definitive answer exists, just social constructs.
Is is right to force selfish humans to vaccinate themselves to prevent doctors from working overtime in countries where health is socialized? I think so. Is it right to ask people to get vaccinated to prevent someone’s grandparents from dying 10 years too early? Well, yes, I believe that’s fair.
You have the right to disagree, but don’t trick yourself into believing there is any universal truth to be found here.
In parent's defense, eating your neighbor is an explicit action. Banning certain actions is indeed inevitable in a society.
Not vaccinating though is an inaction. It's more akin to a right not giving blood every couple of months. Yes, someone may die because of it, but making blood donations mandatory would be a strange thing. Or would it not?
The case isn’t saying that you must be vaccinated.
The question in this case is — does the government have to let your kids attend school without being vaccinated? The explicit action is “attending school”. You can choose to not have your kids vaccinated. That’s your right. But then you have to live with the consequences of that action. In this case, that consequence is not being able to attend preschool in the Czech Republic.
However for virtually every child there's no choice whether to go to school. I don't know if Czech laws say explicitly that school education is guaranteed to the citizens, but de facto skipping school is not an option.
Not clear at all to me that failure to vaccinate is inaction rather than action. Viruses push our understanding of moral culpability and causality, but the comparison to blood donation isn't apt. In the case of donation, we're talking about an abstract stranger, in the case of the virus, perhaps we're discussing a distant downstream effect, but we could also be talking about killing your neighbor or grandma.
Not vaccinating is inaction, but seeing other people while being contagious is not.
We could accuse you of homicide if someone dies from covid because you infected him and that could have been prevented by you not refusing the vaccine. Instead we make vaccination mandatory and consider infection to be an accident, which is the same idea, but more fair.
The first use of complex numbers was as intermediate quantities in the calculation of the roots of cubic polynomial functions. This use is analogous to using negative numbers in a ledger even though negative amounts of physical things don't make sense.
Edit: I meant physical things like apples fam. This is an important philosophical point we don't appreciate because we are so used to them. De Morgan once wrote:
"It is not our intention to follow the earlier algebraists through their different uses of negative numbers. These creations of algebra retained their existence, in the face of the obvious deficiency of rational explanation which characterized every attempt at their theory."
For Arnold, mathematics is rooted in physical intuition and experimental inquiry. Can you name some math that is completely disconnected from that intuition?
Mathematics may be rooted in that, in a historical or pedagogical sense, but areas of math can certainly be disconnected from physical intuition. Non-measurable sets (e.g. those in Banach-Tarski) and transfinite numbers cone to mind.
Non-measurable sets are precisely the kinds of things Arnold wanted marginalized in mathematical pedagogy, instead of placed front and center. They are necessary auxiliaries to the main theory, that of measures and integration but auxiliary nonetheless.
I disagree that transfinite numbers are detached from physical intuition since most of the ones you or I could write down can be easily visualized with a few ellipses here or there. But i do think Arnold would consider them marginal players. Perhaps he thought set theory was a formalist distraction from the main of mathematics!
E.g. logic? A pretty important part of mathematics that is hard to marginalize, but that can't be observed experimentally. Rather scientific observation presupposes logic ability.
That doesn't answer the question. The hypothetical existence of a tachyonic antitelephone presupposes that superluminal communication causes backward time travel. The question is why superluminal communication (allegedly) causes backward time travel, and by what mechanisms.
And no, just because some arbitrary frame of reference is slow to receive information doesn't mean the events creating that information have scrambled causality. Just like how just because I heard lightning strike B before lightning strike A doesn't mean B struck before A.
it's not like a thunder storm. The wikipedia page has a worked out example. If you can go back and forth between 2 places FTL you can arrive before you left and interfere with your departure.
You are more convinced by a metaphor than the actual theory of relativity. That can't be helped.
> The wikipedia page has a worked out example. If you can go back and forth between 2 places FTL you can arrive before you left and interfere with your departure.
That example has multiple assumptions that seem to make said example only relevant to a very specific case, rather than to superluminal communication in general (least of all to approaches specifically designed to avoid those assumptions):
1. Alice and Bob are themselves moving at relativistic speeds relative to each other while communicating. That doesn't seem relevant for cases where they are not doing so - in particular when they are communicating across a region of spacetime crafted specifically such that they are stationary relative to each other.
2. Alice's signal to Bob and Bob's reply to Alice are both somehow themselves moving through normal spacetime at a speed greater than c - i.e. the messages are tachyonic (hence: tachyonic antitelephone). Again, when discussing mechanisms of warping spacetime such that no >c movement within any local frame of reference is actually necessary, bringing up tachyons doesn't seem especially relevant.
> You are more convinced by a metaphor than the actual theory of relativity. That can't be helped.
That can be helped, specifically by explaining why the metaphor is wrong, and where it actually contradicts general or special relativity.
The name tachyonic antitelephone is a bit unfortunate because it need not involve tachyons. All it takes is the ability to send a message outside of your light cone. Along the path actually taken need not be the case, we are reasoning about the endpoints of the communication independent of the means.
In particular it does not matter whether you use a warp drive or not. The violation occurs relative to reference frames outside of the warp bubble where special relativity fully applies. Here, explicitly looks like a worked out example: http://exvacuo.free.fr/div/Sciences/Dossiers/Time/A%20E%20Ev...
You can create instances of FTL travel or communication that don't violate causality. But the ability to perform such FTL tricks implies the possibility of constructing a closed timelike curve so long as you're talking about a localized phenomenon like a warp drive or tachyon where special relativity holds outside of a negligible area.
If you're messing with the global geometry of spacetime then you can make very weird things happen and I would not be surprised if there were such a geometry that allows FTL communication in a limited way that doesnt allow CTCs. But that would not like our universe or a warp drive, a specifically localized situation.
So first, I'd like to say thanks for bearing with me here. I know it's probably frustrating when someone you're talking to just... ain't... getting... it...
...which is why I hate to say that I still ain't getting it, lol
> Along the path actually taken need not be the case, we are reasoning about the endpoints of the communication independent of the means.
So the means doesn't matter at all? It doesn't matter that as far as the endpoints are concerned they're at a fixed distance from one another? That seems hard to believe - not to mention contrary with the math presented in that antitelephone article, which seems to make a big and explicit deal about the relative movement between the two endpoints.
Even when factoring outside observers...
> The violation occurs relative to reference frames outside of the warp bubble where special relativity fully applies.
...how would this apply if the information in question is constrained to that warp bubble between its transmission and receipt? What would there be to observe? If we're talking about side effects of that communication (say, our Alcubierre messenger pigeon drops a feather back into "normal" space somehow), would the propagation of those side effects not just revert back to being subluminal? That is: from every local perspective, the pigeon is traveling subluminally, so this should still apply in the event the pigeon or any signal from it escapes its bubble and reenters "normal" spacetime, no?
...unfortunately, I don't know if it's really agreeing with you. Or me, for that matter.
Namely, it seems to admit that the metric as Alcubierre describes[1] would not produce a closed timelike curve; the paper instead describes ways to produce custom metrics separate from Alcubierre's which introduce the possibility of CTCs, in which case it seems like the answer would simply be to... just not do that, right? Indeed, the paper speculates that there might be other mechanisms that would prevent such a metric from being constructed (specifically naming Hawking's chronology protection conjecture).
That is:
> But the ability to perform such FTL tricks implies the possibility of constructing a closed timelike curve so long as you're talking about a localized phenomenon like a warp drive or tachyon where special relativity holds outside of a negligible area.
Only, from what I can gather, if these equations are indeed the only ones at play, which even that paper admits might not be the case.
So the thing that paper does is it assumes you can make warp bubbles in any reference frame. The original paper makes one warp bubble and this doesn't lead to anything paradoxical.
But if I can make two warp bubbles in two different frames, I can make a round trip that arrives before it starts.
So you need to violate special relativity in a global way to avoid these issues. You have to have a spacetime where only certain warp geometries are possible.
I apologize for being a bit impatient before, these issues are subtle. The only real way to get it is to bear with the math onesself.
> I apologize for being a bit impatient before, these issues are subtle.
No worries, and thanks again :)
> But if I can make two warp bubbles in two different frames, I can make a round trip that arrives before it starts.
Even for the metric as Alcubierre describes? Or for one that's modified per Everett? Now that I'm rereading the Everett paper, I'm not really sure where he's getting his "Lorentz boost"; if there's technically no actual "motion" (because everything's locally at rest and the warp bubble is outright expanding/contracting space around it), then I'm having a hard time figuring out what there would be to "boost", since the relevant Lorentz transformations should be no-ops if everything's locally at rest. Is Everett moving the ship itself at relativistic speeds within the bubble? Is an observer moving at relativistic speeds outside the bubble?
> So you need to violate special relativity in a global way to avoid these issues.
Which the universe kinda already does, no? The mechanism here (from what I understand) is the same as the one driving universal expansion (the difference being that there's no corresponding contraction in the universal case - right?). If that expansion were to be reversed somehow, would that, too, result in causality violations?
And further, doesn't special relativity already only hold in cases with low gravitational potential - so i.e. not in a gravitational field?
A lorentz boost is just a change of perspective. Let's say you have a bubble that is at rest with respect to your reference frame. Well, someone flying by your solar system has just as valid a reference frame as you and they see the bubble moving with respect to them. The relation between their point of view and yours is described by a lorentz boost. Same physical situation, different perspective.
Now, if special relativity holds in the large then there is no reason why they can't also construct a warp bubble. Relative to you and your bubble that bubble is in motion. Since this is allowed, we can construct a closed timelike curve with two judiciously chosen bubbles.
> Which the universe kinda already does, no?
The expansion of the universe does violate special relativity but not in a way that protects warp geometry from creating paradoxes. The kind of violation you would need would distinguish between frames of reference that SR says are equivalent.
> And further, doesn't special relativity already only hold in cases with low gravitational potential - so i.e. not in a gravitational field?
Special relativity holds well enough in most situations that the same argument applies even if you accounted for general relativity except near extreme situations like black holes
Warp drives are not permitted by any deviation from special relativity. You need specific contrived geometries of the entire universe that don't match up with what we know about it.
> The expansion of the universe does violate special relativity
I am curious as to how?
If, we take as axiomatic that there is no such thing as "an object in motion", only "an object in motion with respect to another object", i.e. motion is not a property of an object, but a relation between two objects.
And that since it's 4.3 light-years to Alpha Centauri, therefor a cause (e.g. a radio wave) sent from Earth today cannot have an effect (e.g. an Astronomer writes a paper about it) at Alpha Centauri for 4.3 years, and vice versa. There is 4.3 years of "Absolute elsewhere" to get through first where there is no possible cause-and-effect relation between events. At the other side of our galaxy it's around 100 000 years. And further out, objects are not just far, but receding from us (or us from them, equivalently)
Assuming an unbounded and expanding universe, for very distant parts of the universe receding from us at lightspeed (or speeds faster than light?) and us from them, equivalently. So lightspeed signals from there never reach us, by definition? That part is is utterly unobservable, permanently Absolute elsewhere. The universe's observable edge is a slowed-down red-shift that trails off into the unobservable. In other words, the at no time in the future will those signals have an effect on Earth, or us on them. So, they can't have an effect in our future, let alone our past. No impact to causality at all?
Special relativity describes a flat lorentzian manifold. The uniform expansion of the universe implies that the curvature of spacetime is slightly negative.
Special relativity is not simply a theory of causality but specifically of the geometry of spacetime. From this theory you can derive predictions about specific phenomena, like causality.
But that doesn't mean other spacetime geometries don't share properties with flat minkowski spacetime. Just not all properties. For example there is no cosmological horizon in minkowksi spacetime but there is for our universe.
I got a batch of medlars from a farm this last winter! We ate the first few too soon but the rest were amazing, and very late into the winter when we dont really have fruit besides apples. I'd love for these to become mainstream again.
This paper examines discrimination based on startup founders' gender, race, and age by early-stage investors, using two randomized controlled trials with real venture capitalists. The first experiment invites U.S. investors to evaluate multiple randomly generated startup profiles, which they know to be hypothetical, in order to be matched with real, high-quality startups from collaborating incubators. Investors can also donate money to randomly displayed startup teams to show their anonymous support during the COVID-19 pandemic. The second experiment sends hypothetical pitch emails with randomized startups' information to global venture capitalists and compares their email responses by utilizing a new email technology that tracks investors' detailed information acquisition behaviors. I find three main results: (i) Investors are biased towards female, Asian, and older founders in "lower contact interest" situations; while biased against female, Asian, and older founders in "higher contact interest" situations. (ii) These two experiments identify multiple coexisting sources of bias. Specifically, statistical discrimination is an important reason for "anti-minority" investors' contact and investment decisions, which was proved by a newly developed consistent decision-based heterogeneous effect estimator. (iii) There was a temporary, stronger bias against Asian founders during the COVID-19 outbreak, which started to fade in April 2020.
Unfortunately some women actually in the Coq community discussing this on Twitter noticed they were getting all of a sudden a lot more engagement with concern trolls around the time this submission gained traction. "intellectual curiosity" indeed. I hope its worth it, this place existing. I think I can find a replacement though so I'm logging off indefinitely.