Q&A The Physics and Philosophy of Time - with Carlo Rovelli

If you don't see things changing, is time even passing? If everything has happened is in the past, and everything that's yet to happen is in the future, then what is the present? Carlo Rovelli answers audience questions following his talk.

Carlo Rovelli is a theoretical physicist who has made significant contributions to the physics of space and time. He has worked in Italy and the US, and is currently directing the quantum gravity research group of the Centre de physique théorique in Marseille, France. His books 'Seven Brief Lessons on Physics' and 'Reality Is Not What It Seems' are international bestsellers translated into forty-one languages.

This talk and Q&A was filmed in the Ri on 30 April 2018.

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[TheDaddyO]

There are more Planck times in one second than there are seconds since the big bang (13.7 billion years). That's such a beautiful mindfuck!

[tedlemoine]

The scary thing is the woman who asked the first question was dead serious

[rajkumardhakad]

I love this guy, trying to answer questions in both conventional and quantum thinking, woth such easeness and interest.

[Epoch]

When he says "Let me take this question seriously" to that first woman I almost pissed my is it that when I call New York from Rome they're not in the

[michaelwilliams]

I have Carlo’s book and got somewhat lost when he got onto the subject of entropy. This talked helped a bit as I now understand that my ability to conceive anything further is naturally limited by the ingrained experience of existing in the low entropy of the biosphere! 🤣

[Zendo]

Poor Carlo, I think he must have felt his talk was mostly unappreciated after a Q&A like this..

[Tubularjake]

This lady...this f'ing lady. Listens to like THE expert on time give a talk about time in layperson's terms, and she follows up asking about freaking time zones.... Hats off to Carlo Rovelli for not throwing his hands up and walking out of the room.

[dumpsky]

i like how he generously assumes that the first question wasn't that stupid as it actually was.

[nsjx]

also, when you told that kind lady how to deal with the emotions of Time.... ACCEPT IMPERMANENCE... GOLD!

[mkultra]

Wonderful talk and i enjoyed the Q&A to. I could listen to mr. Rovelli for hours. Please invite him back soon RI! Thanks.

[sumitpratap]

If we loose our Memory and ability to imagine the future, then will the concept of Time become irrelevant? Is time our own making?
Can we fathom time with our intellectual mind?

[IngeniusFool]

What if there are several alien civilizations waiting for us to join them in the timeframe near to a black hole? A conglomeration over billions of years, extinct in their native galaxies respectively even maybe but brought together by gravity. Did anyone entertain that idea yet?

[zzgeekgirlzz]

I understand the entropy concept, and also can see how time is a neurological phenomena, at least largely. But I dont think I heard a hypothesis for why time has an arrow and why, e.g., I can remember the past and not the future.

[tartanhandbag]

1. i thought i was struggling to grasp a few bits here and there, but now hearing the audiences questions, wow, its as if they werent listening at all.
2. cant all the questions be answered by the same idea (which somehow Carlo avoided stating): causality and entropy still exists to drive a process of change (which generates in our mind a distinction between a thing that was and a thing that now is), but these fixed perceptions of time are an illusion. in this sense, time is a human construction based on experiencing entropy. why do we all have this illusion? because its more evolutionarily advantageous to interpret a "flat" time that can easily predict immediate threats than it is to pontificate about the universal meaning of time.

[stevephillips]

I’m inside a black hole. What does time feel like, and could I calculate how long before I was no longer in a black hole?

[thijsh.]

I doubt any of the people asking questions actually truly understood a single thing he was trying to convey to them. I mean, those questions.. just.. what?

[davidwilkie]

You can't ever detect half a Planck length because there's no equivalent constant naturally derived from the Observable universe 's mathematical-modulated integration. Ie what we can see is integrated.., so it "maintains " it's embodiment of integrity, something like the leaves on a tree have individual and collective integrity within specific limits, it's a mathematical property of inclusion and exclusion of primes and cofactors, from which the cause-effect, (total internal reflection-embodiment), is a connected individual and collective conglomeration of phase-states. (Humans are analogue, made of time-duration quanta, and use analogies to communicate and infer what can be from what is, but if the Universe is a single connection, these analogous approximations can never be "true" reality)

The Planck length is an inferred value so any amount of division is possible in the quantizing function of temporal connection-continuity, but by self definition, the duration is too short to relate to the existing resonant general probability of phase states.

A thought experiment might be to imagine compressing a simple gas like Hydrogen, the faster, (= higher frequency), you compress the higher the radiation (by the Exclusion Principle) frequency will be, so if you use a supercollider like the LHC, it is a tool limited by the elements and available energies of its construction, and to get at the Planck length frequencies requires a collider as big as the galaxy(?).
The cause-effect resonance of the Planck length comes directly from quantum effects of superimposed timing that is, ..the Universe.

The Present, Now, is the cause-effect of reflection in the limit of connection of QM-Time "suspended" in nothing, eternally, which is an alternate self-definition of spaced timing, potential and transitional dimensions measured as resonance.

All possible phase states of time-duration resonance are occupied.., by the cause-effect observed as the Exclusion Principle, =>Quantization of Eternity-Now, "measured" out against itself in self-definition. A beginning is also an ending, a cause-effect recirculating Origin like the starting-finishing line of a circular racetrack, that measures time duration against potential possibly of all rates and durations, in that particular dimensional context.

[VoodooDg]

but what about the thing from stephan hawkings books, simultaneousness. where it is describing how you can see the "past" and the "future" by either moving very very fast or "looking" very very far. (because if u dont move through space, you move with c in time in the 4 dimensional space time, and you perceive that spacetime in a 90° degree angle from your movement direction). that should not be a thing if quantum gravity is true, right?
in quantum mechanics/relativity this is certainly true.

[niranjandev]

The Philosophy of Time is well describe in simple language.The human machine limitation are added, however there is no physical existence beyond function of time.

[captainharris]

I'll say this, mister Rovelli has a whole lot more patience with an audience that didn't understand a single concept he tried to convey and were still asking questions about "time" when he clearly explained why "time" was real. I would have blown a fuse, thrown my mic on the floor, and then stormed out of the room.