Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

A growing number of scientists are convinced the future influences the past

vice.com

Post reply on HN
Print view View original

161–170 of 455 posts

Re: A growing number of scientists are convinced the future influences the past

#161

Post by ocimbote »

QuercusMax wrote: post #115
dietrichepp wrote: post #20

Earlier quoted context omitted.

I used to work at camp. You didn’t need to tell kids about fire; they could figure it out. Don’t touch the fire. Flashlights were too complicated. It’s night, a kid turns on their flashlight, points it in their eyes, says “ow” and can’t see where they’re walking until their eyes readjust. Flashlights are beyond our instinctual understanding of how the world works.

Maybe this is just because the kids had prior experience with fire (touch it = ouch), but no experience with flashlights?

Yes. If we learned something about fire, it's to teach the youngest ones to stay away from it. Nothing more. An unattended and untaught kid will try it, at least because it's nothing like they've seen before.

Re: A growing number of scientists are convinced the future influences the past

#162

Post by PartiallyTyped »

a257 wrote: post #97
soperj wrote: post #90

Earlier quoted context omitted.

> And no practical amount of shaking the jar will ever return the marbles to a high order state again. This can't be true. Take the case where there's only 2 marbles, it's likely that at some point that shaking them will return them to the original state. For higher numbers of marbles the probability becomes lower and lower, but is never 0.

With enough marbles, the discrete distribution behaves like a continuous distribution. The point probability of a continuous distribution is infinitely improbable -- in other words it is 0. (0.00..0..1 = 0 just as 0.99 repeating equals 1)

Any point is infinitely improbable when sampling with infinite precision, only because this calculation is not computable.

Even if the point probability is 0 or approaching zero very fast, some event occurs with probability 1.

The probability that life would evolve on a blue planet that its anthropomorphic inhabitants will come to call Gaia or Earth, has as a star Sol, in this corner of the Milky Way, in this particular local group and so on is zero even if we limit ourselves to just the observable universe.

At the same time the probability that life will exist at some planet at some solar system at some galaxy at some local group and so on, is practically 1.

That is to say, depending on how you categorise and count said marbles, the reordering may occur.

While any individual marble will not be at its place with P=1. You can still end up in a situation where the marbles are ordered in layers.

The whole thing regarding entropy is concerned with a closed system. You can very much exchange energy to decrease entropy, but said exchange is a) leaky, and b) implies that the system is not isolated.

Re: A growing number of scientists are convinced the future influences the past

#163

Post by a257 »

soperj wrote: post #154
a257 wrote: post #97

Earlier quoted context omitted.

With enough marbles, the discrete distribution behaves like a continuous distribution. The point probability of a continuous distribution is infinitely improbable -- in other words it is 0. (0.00..0..1 = 0 just as 0.99 repeating equals 1)

There can't be an infinite number of marbles in a finite amount of space.

The number of possible states asymptotically approaches infinity, so we can model it as such. You can get a more "accurate" model using more math (with measure theory), but the terms will coalesce such that they are negligible.

Re: A growing number of scientists are convinced the future influences the past

#164

Post by photochemsyn »

0xBABAD00C wrote: post #134
jonny_eh wrote: post #77

> It may seem eerie to our brains, which process events sequentially, but the history of science is also littered with examples of human biases leading to bad conclusions, such as the Earth-centric model of the solar system. Slow down. Assuming that time moves in one direction is not comparable to geocentrism.

Here's the analogy, per Sean Carroll [1]: - There seems to be a special direction "down", where things fall by default, because we live in the vicinity of an influential object in space, called Earth - There seems to be a special direction "forward in time", where things happen by default, because we live in the vicinity of an influential event in time, called Big Bang If we had stuck to the local Earth context and g…

It's difficult to see how such a hypothesis could be tested either experimentally or observationally. Sounds more like metaphysics?

Stars shine until they run out of fuel, and the age of a star - the status of its fuel, the buildup of fusion products - happens as time passes. Life on planets taps into the flow of sunlight from the star (and/or the flow of heat and chemical energy from the a hot planetary core) to generate complex structures in defiance of the regular direction of entropy (not violating conservation of energy, though). So... life reverses the arrow of time?

Re: A growing number of scientists are convinced the future influences the past

#165

Post by bsder »

jonny_eh wrote: post #77

> It may seem eerie to our brains, which process events sequentially, but the history of science is also littered with examples of human biases leading to bad conclusions, such as the Earth-centric model of the solar system. Slow down. Assuming that time moves in one direction is not comparable to geocentrism.

> Slow down. Assuming that time moves in one direction is not comparable to geocentrism.

Why not?

The "arrow of time" almost always requires thermodynamic arguments. And that requires a concentration of "low entropy" to move toward "high entropy". Which, by definition, are "boundary conditions" and not a fundamental part of your physical rules.

If, for example, your universe is entropically uniform, is there an "arrow of time"? And, even if there were, could you detect it?

However, I would like to point out that it's not like we haven't had this kind of issue before. The Bohr-Einstein debates were a good example. Einstein favored a "fields" interpretation of quantum mechanics. Unfortunately, Einstein's interpretation predicted that atomic states wouldn't decay, and that was clearly, obviously wrong, and Bohr very much hammered on that.

Except that Einstein wasn't "clearly, obviously wrong." As you increasingly isolate excited atoms, their atomic states take longer and longer to decay. The problem was that the experiments of the day couldn't create these kinds of singular quantum state systems--they were stuck with systems that were contaminated with lots of thermodynamic interactions.

We may be seeing something similar here. We are just starting to be able to put together the experiments that can probe things like Bell's Inequality. As we isolate these systems, we may find that the systems were contaminated with statistical time and that we get different results when we can isolate them.

Re: A growing number of scientists are convinced the future influences the past

#166

Post by TechBro8615 »

a257 wrote: post #158
TechBro8615 wrote: post #135

Earlier quoted context omitted.

> infinitely improbable -- in other words it is 0 This sounds like a rather bold statement to make, as long as we're already speaking so metaphysically.

The statement is mathematically correct [0]. [0] https://stats.stackexchange.com/questions/142730/px-x-0-when...

We're talking about physics, not mathematics. We don't have the luxury of hand-waving away fundamental questions about the nature of the continuum.

See: https://en.wikipedia.org/wiki/Continuum_hypothesis

Re: A growing number of scientists are convinced the future influences the past

#167

Post by richardw »

Honestly it’s been staring us in the face for 100 years. Light doesn’t experience time. We’ve known this for so long. Light is created and destroyed in the same instant - across billions of light years it happens instantly. For that to be true, what else must be true? Must.

There is no photon. There is just a wave. The interaction probably (definitely?) depends on features of both the emitting electron and absorbing electron. There is either retrocausality or superdeterminism (or both). We don’t know which. Right now that’s not important but scientific fashion has been refusing to get this one thing. We’ll learn so much once we move past this.

Light going into a black hole? Research paper.

Re: A growing number of scientists are convinced the future influences the past

#168

Post by a257 »

PartiallyTyped wrote: post #162
a257 wrote: post #97

Earlier quoted context omitted.

With enough marbles, the discrete distribution behaves like a continuous distribution. The point probability of a continuous distribution is infinitely improbable -- in other words it is 0. (0.00..0..1 = 0 just as 0.99 repeating equals 1)

Any point is infinitely improbable when sampling with infinite precision, only because this calculation is not computable. Even if the point probability is 0 or approaching zero very fast, some event occurs with probability 1. The probability that life would evolve on a blue planet that its anthropomorphic inhabitants will come to call Gaia or Earth, has as a star Sol, in this corner of the Milky Way, in this particu…

A probability of zero does not mean that the event is impossible. When we refer to probabilities we are talking about probability densities. Infinite precision is a useful modeling tool in the same way that approximations of pi are useful.

Re: A growing number of scientists are convinced the future influences the past

#169

Post by resource0x »

7thaccount wrote: post #105
jonny_eh wrote: post #77

> It may seem eerie to our brains, which process events sequentially, but the history of science is also littered with examples of human biases leading to bad conclusions, such as the Earth-centric model of the solar system. Slow down. Assuming that time moves in one direction is not comparable to geocentrism.

Yep. Someone else already pointed out the well known counterargument to symmetry below regarding thermodynamics. You typically don't see scrambled eggs become whole again. I think that's pretty hard evidence to overcome. Granted, I'm not a physicist and I'm sure any physicist working on this totally understands that. Just wanted to point it out.

If the direction of time is reversed, the eggs become whole again, but your memory of them once being scrambled is reversed, too, so you don't notice anything unusual.

(It's like a rollback of database transaction, where not only the database state, but also the state of everything, including your brain, is getting rolled back)

Re: A growing number of scientists are convinced the future influences the past

#170

Post by VeninVidiaVicii »

brwck wrote: post #155
epgui wrote: post #102

Earlier quoted context omitted.

I disagree, I think the comparison is pretty reasonable. Your entire experience of the world is defined and limited by the fact that your brain "only processes information in one direction of time" (for lack of better wording). Your personal experience does not necessarily map correctly to the real world. The same is true for both examples.

It's not just a matter of our subjective experience of time, it's a matter of the laws of thermodynamics and entropy. Time moves in one direction is another way of saying entropy always increases. If time could move in the opposite direction, then entropy decreases which breaks our understanding of physics.

It's really interesting to think about how we struggle to express the idea of the future having a causal impact on the past. I reckon this is because our language and our understanding of time are limited.

Our brains like to process events in a linear sequence, from past to present to future, but this view of time might not fully capture how everything in the universe is interconnected. It's possible that our language just can't handle these complex concepts.

So, I don't think anything mentioned in this thread contradicts the idea that "time always moves in one direction" and "entropy always increases".

Post reply on HN