Simone Rijavec

Running fallible code

[Conjecture Institute @ConjectureInst]

⚛️📚Bold Conjectures, Volume II: Essays Across Physics

excerpt from @s_rijavec's essay

The Quantum Solution to an Ancient Problem

Time is a concept that pervades our everyday lives and is central to our understanding of reality.

However, it is beset by deep explanatory problems.

In physics, our best theories of time suggest that we live in a block Universe.

The block Universe itself is timeless, yet within it all the different nows somehow coexist. Since classical physics does not allow multiple realities to coexist, we face a serious conceptual issue.

In this essay, we illustrate how quantum theory addresses this and other problems related to our classical conception of time.

In quantum theory, the different nows are simply different branches of the overall timeless state of the Universe.

The quantum explanation of time sheds light on questions that humans have wrestled with since antiquity and lays the conceptual foundations for a quantum theory of gravity.

[Simone Rijavec @s_rijavec]

"The Druids [...] are said there to learn by heart a great number of verses; accordingly some remain in the course of training twenty years. Nor do they regard it lawful to commit these to writing, though in almost all other matters, in their public and private transactions, they use Greek characters. That practice they seem to me to have adopted for two reasons; because they neither desire their doctrines to be divulged among the mass of the people, nor those who learn, to devote themselves the less to the efforts of memory, relying on writing; since it generally occurs to most men, that, in their dependence on writing, they relax their diligence in learning thoroughly, and their employment of the memory."

[Conjecture Institute @ConjectureInst]

Read Conjecture Institute Fellow @Sam_kuyp & @s_rijavec's paper

Measuring time in a timeless universe

https://t.co/qGtKyVvFsu

Read Conjecture Institute's Handbook

https://t.co/3Ii148Ptj9

[Dr Maria Violaris @maria__violaris]

Is it time to quantize time?

Everything is quantum in quantum mechanics... almost. Time remains a mysterious flowing quantity slotted in to the equations. Surprisingly, there's a model for making time quantum, with a radical consequence: the overall universe is timeless.

How is it possible to experience a flow of time in a timeless universe?! Find out in my latest episode of the Quantum Foundations Podcast with Simone Rijavec, @s_rijavec!

We discuss the Page-Wootters model for the emergence of time in quantum theory, and get an insight into Simone's research on the topic.

Here's how physicists are solving the problem of time in quantum theory, explained in 60 minutes:

00:00 Coming Up

00:59 Intro

01:37 Simone's journey into quantum

05:04 The problem of time in quantum theory

07:07 Relational approach to time

11:12 Quantum measurement and time

17:53 Stationary universe and the Wheeler-DeWitt equation

30:18 Multiverse & block universe

31:11 How is time flowing?

34:20 Problems with wave-function collapse

36:11 What are clocks?

37:48 Resolution of time-steps

41:47 Debates on the timeless approach

45:08 Interactions with clocks

51:05 Recap

57:39 Making time fully quantum

1:00:43 Behind the Scenes

[Conjecture Institute @ConjectureInst]

Conjecture Institute is honored to announce our Senior Scientist, Oxford physicist Chiara Marletto!

Dr. Marletto leads a new research group that is developing constructor theory, a new theory that aims to express all laws of physics in terms of possible and impossible tasks.

[Charles Alexandre Bédard @CABedardPhysics]

The standard claim that the Schrödinger and Heisenberg pictures of quantum mechanics are equivalent assumes an instrumentalist worldview, in which theories serve only as tools for prediction. Under scientific realism, the verdict is different.

https://t.co/DzdEftT7Hf

[David Deutsch @DavidDeutschOxf]

More about time. About time! https://t.co/zF7Y9Vrniq

[Conjecture Institute @ConjectureInst]

Read @s_rijavec and Conjecture Institute Fellow @Sam_kuyp's new physics paper, 'Measuring time in a timeless universe'!

Both Simone and Sam will be at Rat Fest 2025 this weekend, too😉

👇

[Simone Rijavec @s_rijavec]

@ELuttwak Can you please provide a link?

[Conjecture Institute @ConjectureInst]

"...researchers in quantum foundations are still convinced not only that a local description of quantum systems has not yet been provided, but that it cannot exist.

The main goal of this paper is to address this misconception..."

~Conjecture Institute Fellow @CABedardPhysics

[Conjecture Institute @ConjectureInst]

Som Rat Fest 2025 Talks:

@DavidDeutschOxf Audience Q&A

@s_rijavec Simone Rijavec: The Emergence of Time in Quantum Theory

@ToKTeacher AI and the Philosophy of Science

@beigege Addiction

@astupple The Sovereign Child Q&A

@fakeryofficial Wrong about Art

[Simone Rijavec @s_rijavec]

@sphexish @Sam_kuyp One can think of the block universe as the limiting case of a universe with a clock capable of distinguishing arbitrarily small time steps, a so-called "ideal clock".

[Sam @Sam_kuyp]

My new blog post about a recent paper by @s_rijavec and me, on the physics of time and, in particular, on how to measure clocks in a stationary universe.
https://t.co/tb3yJX1Idt

[popperazzi @poppermemes]

huge if true

[Sam @Sam_kuyp]

@S_Rijavec and I wrote a paper, ‘Measuring time in a timeless universe’, that just appeared on the arXiv.

We demonstrate that quantum clocks, typically assumed to be isolated and therefore unmeasurable, can in fact be measured.

https://t.co/sxfkDcUeth

[Dr Maria Violaris @maria__violaris]

Had a great time at #BQIT! It was fun to organise & chair the foundations & thermo session, with excellent talks from @AlexiaAuffeves, Twesh Upadhyaya & @GerardoAdesso, and to present a poster about my teleportation-themed project with @s_rijavec & @CABedardPhysics.

[Simone Rijavec @s_rijavec]

@StefanoGogioso Really cool! Is this equivalent to the Page-Wootters approach?

[Oxford University Quantum Information Society @quantuminfosoc]

We are hosting Flaminia Giacomini tomorrow, the 22nd of February at 6 pm.

She will explain how quantum information tools can be used to go beyond the classical notion of spacetime.📏⏱️

Click Here to sign up for the Zoom link: https://t.co/NzWxHw3otK

[Oxford University Quantum Information Society @quantuminfosoc]

Join us on Thursday (26th May) at 4:30pm as we talk to
@nicoleyh11 about her latest book, “Quantum Steampunk: The Physics of Yesterday’s Tomorrow”!

Sign up at: https://t.co/hu6ZInDLMk
Or see more about the book below :)

[Oxford University Quantum Information Society @quantuminfosoc]

At 6pm BST on Wed 18th of May we will be hosting Denise Ruffner and Robin Coxe from Atom Computing! Join us to hear their perspectives on quantum hardware and the quantum ecosystem. Sign-up below:
https://t.co/MzNmWVrsfA