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Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time

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Re: Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time

#121

Post by placebo »

jerf wrote: post #65
_8j50 wrote: post #54

Earlier quoted context omitted.

I was defining time as the measurement of change. Change does not depend on measurement therefore there is no circular definition. For example, a star is different from star light. When I look at the sky through a telescope I don't see a star,I see star light. Same can be said for any object as well,we see light emanating from an object therefore vision is perception of an object as measured by our optics. Time is ho…

The problem is that if you take the time and carefully consider all of your statements, and carefully lay them all out in a row in the right way, you will find you've got circularity hiding in them. I am confident in this statement because you are walking very well-covered ground, and lots of smart people have examined it all very closely. For instance, "change" intrinsically has a before and after element in it; you…

I'm in agreement about the uselessness of words to define time, but I doubt that even using math will help understand time. I'd argue that both math and time arise with thoughts, i.e with the faculty of defining concepts and reasoning about them, but defining a concept is not the same as understanding the essence of the thing that is being defined. I see mathematics as the extent to which "thought muscles" can be flexed (which admittedly is very impressive), but to understand the nature of time, one would have to "step out of thought" as well, which if possible would be a rare capability and obviously not an insight that could be conveyed with explanations or definitions...

Re: Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time

#122

Post by tigershark »

andrepd wrote: post #37
_8j50 wrote: post #20

I think I'm a simpleton because I could never imagine time being it's own thing. I see time as simply the amount of change in reality we can perceptually sample. Much like how an object in motion will continue in it's motion until it meets resistance,reality in my opinion is in continuous motion that has yet to meet resistance. Time (imo)is our measure of this change divided by our ability to sample it(where this abi…

Right, however relativity tells us that time is an actual, physical thing that can be affected by and affect matter.

What do you mean with “actual, physical thing”? Unless I missed some quite huge news I don’t know about any particle that “creates” time unlike Higgs boson that “creates” mass. Obviously the “creates” is a huge over-semplification.

Re: Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time

#123

Post by Maro »

hansen wrote: post #117
Maro wrote: post #112

Earlier quoted context omitted.

I respect your point of view, but I don't really agree. A popular science understanding of BHs, BB, QM is not really an understanding. It's just some fairy tale level understanding. To be clear, I'm not being elitist, using QM as an example, I think it was Feynman who said nobody really understands it, at best we can make calculations/predictions ("shut up and calculate"). For example, ask a lay person about BB and t…

> For example, ask a lay person about BB and they will tell you it's an explosion, in the classical sense Give her Weinberg’s book to read and she’ll come to a different conclusion. Of course those books won’t give you a deep understanding of cosmology but that doesn’t mean they have to be completely wrong. Stephen Weinberg’s The First Three Minutes is my favorite example of pop-sci done right.

My initial comment was probably too much gut-reaction.

There is good popular science that is useful.

For example, maybe the designers of Mario Kart read about QCD and the strong force: this is a weird force, which---unlike electromagnetism and gravity---gets stronger (not weaker) with distance, like the pull on a rubber band. Maybe they read that, and that's how they came up with the game's rubber band mechanics.

But I do think a lot of the highly publicised stuff is unfortunate, because they deal with highly speculative stuff (ST) and/or give the reader a false sense of understanding (BB), and in general writing 300+ pages of high-level hand wavy explanations is of questionable use to me; I'd make it shorter and give it away for free.

Re: Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time

#124

Post by hansen »

oldandtired wrote: post #119
hansen wrote: post #108

Earlier quoted context omitted.

Yeah, science isn’t about being useful and relevant in day to day life. It’s an important part of human culture and scientist should at least try to communicate their findings to general public (which is paying for it!). I partially agree with the first comment that it isn’t really helpful to popularize highly speculative – and thus probably false – ideas. But well established but still “weird” discoveries like GR &…

The problem with the "well established" or "settled" discoveries is that there is enough experimental evidence that is anomalous to the theories thus presented. This effects everything from the ideas from General Relativity, Special Relativity, Big Bang, Quantum Mechanics, the Standard Model of Particles, etc. I think the biggest problem that is faced today (it hasn't really changed in centuries) is that people do no…

> there is enough experimental evidence that is anomalous to the theories

Huh? I have more the impression that Λ-CDM & SM are working just too damn good. I’m not aware of any observation that hints that we need something completely different than GR & local QFT.

But “settled” and “well established” doesn’t mean that humans will never find a more fundamental theory. Classical mechanics is settled, well established and correct as it was in Newtons times. Now we just better understand its limits and when to use different models.

GR, QM & QFT are correct and won’t go away. At some point in the future we will have a better understanding of their limits too. But that won’t make them wrong.

> The fact that we don't know and that our current suite of theories is incomplete and hence could very well be wrong in both minor and major ways should be driving us onward into understanding the universe around us. It really is not a problem if we don't understand. It should mean that we strive to learn more.

I’m not objecting exploring new speculative models. I’m worried about presenting highly speculative ideas as facts or probable solutions to the public. A lot of the pop-sci articles you read these days are very misleading. And IMHO Rovelli, Green, Susskind, Smolin and the like aren’t doing anyone a favor with their pop-sci books.

Re: Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time

#125

Post by Maro »

dempseye wrote: post #116
Maro wrote: post #112

Earlier quoted context omitted.

I respect your point of view, but I don't really agree. A popular science understanding of BHs, BB, QM is not really an understanding. It's just some fairy tale level understanding. To be clear, I'm not being elitist, using QM as an example, I think it was Feynman who said nobody really understands it, at best we can make calculations/predictions ("shut up and calculate"). For example, ask a lay person about BB and t…

> It's just some fairy tale level understanding. This has value in itself, as the first step towards greater understanding. I bet most people who study physics had their interest piqued by such fairytales. Maybe you did too.

> I bet most people who study physics had their interest piqued by such fairytales.

Okay, but that's the education use-case for young people. For them, a 300+ page book that talks about the arrow of time and costs $25 is not the right thing, in my opinion.

If you look at Feynman's stuff, those are good examples, that's what got me hooked as a student. I pirated the Feynman Lectures on Physics mp3s and pdfs and chewed through it, after being initially inspired by Surely You're Joking.

Re: Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time

#126

Post by rufugee »

Maro wrote: post #101

Disclaimer: I'm a physicist who didn't finish the Phd and went to work in the tech field instead. I wish physicists would stop writing these bullshitty popular science books. A lot of the books are popularizing unverified / unverifiable things like String Theory or Multiverse or Arrow of Time. And when they're talking about more plain things like Special Relativity, then I still cringe, because it's not something tha…

I Feynman is the right approach to teaching physics to the lay person...which book is the place to start?

Re: Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time

#127

Post by redial »

mcbits wrote: post #100
redial wrote: post #97

Earlier quoted context omitted.

The question is "are" there any blue reds. In other words, regardless of who is watching it, or if anyone at all. The question is not "can we perceive" some reds as blue.

There are no blues or reds at all if nobody is watching. Color is a purely perceptual phenomenon relying on properties of the eye and brain.

Not true, what we call the color red is an electromagnetic wave with a wavelength between, according to wikipedia, 625 and 740 nanometers.

And if you are looking at a picture on a computer, the computer will call red a pixel with an rgb value of (255, 0, 0) even if nobody is looking at it.

Re: Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time

#129

Post by dyukqu »

acqq wrote: post #93
uh_what wrote: post #91

Earlier quoted context omitted.

Your post kind of rambles on and fails to address the point that OP is making: Physics is, in fact, stuck. It's been almost 100 years since the initial clash between classic mechanics and quantum theory, and how much closer are we to unification? And you take an extremely condescending tone while addressing OP's lack of humility while making statements attacking him for "especially from one not understanding how scie…

> Physics is, in fact, stuck I'm trying to explain that it is not "stuck" in the sense in which the casual readers tend to perceive it. The scientists actually have what to do, and will have what to do, no problem with that. It's just that it's harder to get the budget for the kinds of investigations that extend the area of our knowledge. And that some "pet hypotheses" of some scientists remained unconfirmed. What is…

Hey, thank you for your time and effort for putting all the links and information on your comments.

Firstly, I'm not against experimentalists and/or experiments and the money spent for them - it's not even "peanut" compared to military projects all around the world, as you stated. What I wanna say is that (to a curious outsider) it looks like there are so many experimentalists (and physicists-turned-to-pop-sci-writers) than theorists so physics suffers from the lack of beautiful power of imagination of human mind. True, I'm not a perfectly-informed one about all the things going on in the filed, of course, but I'm not completely uninformed one too, I guess.

Secondly, I'm not a native English speaker so I thought about the tone of my comment after I finished writing it and read it couple times and asked myself "Does it sound harsh or something like that to...anyone?". So I put down those "2 cents" and "humble" things at the bottom of my comment trying to show that I'm not an insider and I'm not trying to pick on anyone personally. Pardon me if it looked like the opposite.

Re: Carlo Rovelli on the ‘greatest remaining mystery’: The nature of time

#130

Post by vermilingua »

_8j50 wrote: post #43
gowld wrote: post #25

Earlier quoted context omitted.

Sounds good. Next, please define "change", and explain why or how "change" exists and is detectable by humans. That's what Rovelli is investigating/theorizing about.

Yes but they are investigating our relative perception of the change. It's like studying astronomy without considering the fact that the stars we perceive in the sky is just our perception of how they looked like in the past. We distinguish how things are now from what we can perceive by measuring light and EMR. Why can't we at least consider the possibility that our perception of change might be different from the a…

You don’t need to consider that what you see in the sky is “in the past”. The light that’s reaching us has been travelling at c, the universal speed limit. Since we cannot possibly have known about that information sooner, what we see in the sky is for all intents and purposes, “the present”.

Additionally, the hidden variables of the change are exactly what they’re talking about when people ask the question “what is time?”.

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