xdarnold

Your position is more or less defensible, but you will have to accept some compromises to your description of the universe that most physicists find untenable.

Actually, it is Bell's Theorem / Inequality and related experiments that are relevant here. https://en.wikipedia.org/wiki/Bell%27s_theorem

These experiments were really the nail in the coffin for Einstein's position for most physicists. Having to admit non-local hidden variables is a pretty distasteful result.

I'm not making anecdotal conclusions or assumptions about whether people walk around or go into work, I'm simply stating the facts here based on considerable research.

Influenza is a useful proxy for the cold, because we have plenty of data on influenza strains with R0 very close to the cold.

Perhaps the most contagious disease we've ever encountered, the measles, has an R0 around 18. Before the 1960's, when the vaccine was licensed, we saw incidence rates as high as the .8% range yearly for measles. That is 20x more than influenza, but still orders of magnitude short of the 50% number you threw out there.

The cold and influenza both range from R0=1.3, to perhaps 6 on the very high end of estimates. 50% just isn't reasonable by any measure.

As for comparisons to this nCoV, it's still very early days and there are many unknowns. Still, there is no evidence to support an R0 even remotely close to the measles. 50% simply isn't plausible or reasonable, based on everything we know about viruses and epidemics.

Of course in many ways they are different, but not in the important ones for this discussion.

I used influenza because it was convenient in terms of available research, I could grab in a minute or two, but I'm sure if you care to look you can find similar data for rhinovirus.

Rhinovirus and influenza have very comparable R0's. R0 is the epidemiological measure of the "contagion" factor of a pathogen.

Replying myself to add reference, here:

https://www.ijidonline.com/article/S1201-9712(19)30354-6/pdf

This is all well understood, and studied in considerable depth.

The media overreaction is typical, but here at HN we are better than that and we should strive to rely on established science (where available). No need to throw out extreme or unreasonable numbers!

Over any time frame, it's still quite extreme. To use influenza as a proxy, which has virulence comparable to the cold, the yearly incidence rate in China is <35 per 100,000. Even if this is a full 100x worse, we aren't even getting close to 50% infection rate over the season or a 6 month time frame.

This is incorrect.

If we assume that this virus is as infectious as the common cold, we can expect the infection rate within a household to be approximately 25% of contacts. That means that of the people you LIVE with, 25% will catch it from you.

50% infection rate in a large, distributed population like China would be very extreme.

This is nothing more than the illusion of a stance so long as the statement on Weibo stands. Publicly calling Morey's statement "inappropriate" and "disappoint[ing]" and expressing regret for it cannot be reconciled with supporting free speech.

> Decoherence is a superposition effect, is it not? Entanglement with the environment, i.e. a superposition of system-environment states.

The point I'm trying to make is that "splitting", while sometimes identified with decoherence, isn't superposition (or any other well defined traditional QM phenomenon). It's a term peculiar to MWI and it importantly has no clear canonical technical definition. It generally refers to something just considered abstractly: the branching of a single _universe_ into multiple. If you use "split" and "entanglement" or "superposition" or any other QM term interchangeably, you are bound to invite misunderstanding.

> ...illuminate their question about superpositions propagating...

Agreed... if that was their question. But their question didn't reference superposition at all, it was about a split propagating:

> ...a quantum event occurs here and the universes split, that split propagates out at the speed of light...

Which is why I responded as I did. It is understandably confusing to wonder what it means for propagating split universes to meet years later, if you start talking about splits in this way. Propagating superposed particles? Much easier to make sense of.

All depends on the context. Does it make sense to talk about propagating splitting in this context? Surely no - for three reasons:

1. You're describing a time evolution _of the subsystems_, which isn't really a thing in the MWI.

A many-worlder would say, instead, that the Universe has split a bunch more in the interim. He would point to the time evolution of the state of the Universe, and perhaps there have a discussion about how the inseparability of particular subsystems has propagated over time. Put differently, the many-worlder might say the correlations of these particular relative states with one another propagated over time.

What you've done, Everett would call characterizing branches of the universal state in a space-like locality.

2. Split != superposition. Frequently, splitting in MWI is identified with decoherence, so in that sense there is a self-consistent way to describe local splitting - but then you'd really mean, when you referred to the splitting of "an object" or "a system", that Universal splitting had occurred in such a way as to cause the object to exist in some particular multiple new branches.

3. None of this line of discussion helps the parent gain an understanding of how MWI is importantly different from (and the same as) other interpretations of QM. It's far too shallow to amount to any real expert insight and yet too technical to amount to any real layperson insight.

What can a discussion on propagating splitting illuminate here? It seems to me that it is a less than useful idea for the parent and readers like him/her, and many-worlds is more clearly understood without it.

When we talk about MWI as the asker is trying to more fully understand, we are explicitly not talking about subsystems. There's just the one big evolving state (of the universe).

Your choice of the future here is arbitrary - we could just as easily say that there are many past and present "you" in the multiverse. This assumes a definition closer to DD/DW's than the author's.

The author seems to assert that his experience of self is incongruous with this definition of your identity. As a historical fact, "you've" always either chosen chocolate or vanilla, not both. The other branches aren't in fact you, any longer.

"Splitting" does not propagate, or happen with any locality - it's the wave function of the entire universe doing the splitting, so there's nowhere for it to propagate!

Your objections seem to me to arise straightforwardly from a disconnect over the definition of "you". Taking DW's position, and your axiom of unique self, I can resolve the issue by saying something like:

Knowing that you can never be certain which branch you will end up in, bet on the outcome that maximizes the liklihood that you will end up in a branch you favor. Your bet, of course, will follow the form of the Born rule.

With today's technology, for some compounds... you can count atoms by physical measurements and known structure, and figure mass by atomic weight.

http://www.nist.gov/pml/si-redef/kg_new_silicon.cfm

This is potentially an interesting effect and worthy of some consideration, but the analysis needs to include some regression of this possible factor:

An increased number of errors on "return" lines.

Which naturally should be more frequently last lines than otherwise.

I don't think I'm understanding your point. Why would they need to invalidate previously confirmed transaction?

Why is this?

My understanding of the way the network operates is that a group with 51% of hashing power can essentially arbitrarily manipulate the blockchain going forward. Nothing could stop them from confirming otherwise invalid transactions (re-spending the original outputs) and mining those new transactions. After which, clients, only looking backwards to the first block a transaction resides in, wouldn't notice that the funds were originally double-spent.

100% agreed - this would certainly undermine the movement. The open question is whether it would do so more or less than the loss of half a billion dollars held by the community. I'm not sure what the answer is, but shouldn't every option be on the table?

I'm not making that assumption - rather the opposite, which is why I mentioned the possibility of reimbursing people later. But this isn't strictly necessary. Pragmatically, you could double spend the coins back to the original owners and then make decisions about downstream action independently. Investigation of what happened to the stolen coins might provide more clarity on the best course of action there.

I don't think this is what I'm suggesting at all. If a popular majority of miners agreed to accept transactions double spending the original coins, this would be tantamount to generating 750k new Bitcoin, not initially invalidating any blocks or other transactions.

With forensics on the initial theft, miners could then tree-traverse back up to blacklist future transactions on stolen coins. There are probably lots of ways to accomplish basically this. This would render all stolen btc dead in the water, hence the "force Gox to repay legitimate requests for reimbursement of those who transacted for stolen coins."

That second part, though, isn't crucial to the idea. The community could just double spend the coins to mitigate harm done without attempting to stop the stolen coins downstream.

It seems like there is a straightforward enough principle in this case to do so without much argument. Not that the method would be perfect. But isn't it preferable to the alternative?

Under the presumption that it is true that ~750k BTC has been stolen, has anyone considered the possibility of orchestrating a 51% attack on the attacker(s)?

Gox probably has logs of withdrawal requests. It might be daunting but feasible to sift the tx-MAL withdrawals from legitimate ones, then work with major pools and exchanges to double-spend stolen coins back to Gox.

Gox could then be forced (by the same 51% majority) to pay legitimate requests for reimbursement by vendors or 3rd parties holding stolen coins they transacted for goods or services, given reasonable documentation. Leaving us with some but not unacceptable collateral damage.