Celebrating 10 Years of Foundational Questions in Physics and Cosmology!
FQXi’s most popular online content from the past decade

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FQXi launched in May 2006 to catalyze and support research on the foundations of physics and cosmology. To celebrate our 10th anniversary, we're showcasing our top 10 most popular articles, videos, podcasts, essays and the 10 hottest discussion topics at the frontiers of physics, for the past decade. Thank you to the FQXi community, including our contributors, funders and visitors to our site.

Top Articles | Top Videos | Top Podcast Stories | Top Forum & Blog Topics | Top Essays



"What is Time?"

David Eagleman, Paul Davies, Tim Maudlin, Raissa D'Souza and moderator Jennifer Ouellette.

"What is Consciousness?"

Christof Koch and Giulio Tononi

"String Theory v Loop Quantum Gravity"

Carlo Rovelli and Raphael Bousso

"Is the Multiverse Real?"

Max Tegmark

"Boltzmann Brains and Eternal Inflation"

Sean Carroll

"Is Consciousness a State of Matter?"

Max Tegmark

"Does Time Exist?"

Julian Barbour and Tim Maudlin

"Complexity: Living Systems from Cells to Cities"

Geoffrey West

"Is Time an Illusion?"

Julian Barbour


Hot Topics from Forums and Blogs

Alternative Models of Reality
Zeeya Merali

If you have an unconventional, alternative model of reality, then this is the place to discuss it. (This is for contributors who have preliminary ideas and would like feedback, but do not have an academic paper or arXiv preprint and have not given a conference talk based on their ideas.) Edited on 31 August to add: Thanks to Peter and John for commenting on my recent Nature article: "The Origins of Time and Space," which surveys some of the recent ideas on reality, and could serve as inspiration for this thread. :-)

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Sears and Zemansky 13th ed.

Summary of Chapter ! (page 26):

"Physical quantities and units: Three fundamental physical quantities are mass, length, and time. The corresponding basic SI units are the kilogram, the meter, and the second. Derived units for other physical quantities are products or quotients of the basic units. ... "

'Physical quantities' means the modern authors are speaking of rules of measurement. "Derived units for other physics quantities ..." means the...

These are operational definitions just as S&Z state in the 13th Ed. just because mass, length, and time are all axioms. Science simply has to believe in the measurement rules using light to define all three.

I should have also mentioned that practically speaking, science can measure the mass of light as momentum, but the IPK is still more precise. The new watt balance that is mentioned in the article will replace the IPK and will weigh the power in a superconducting loop of electrons. In...

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These are the 10 most popular essays, receiving the most hits from visitors, over the past decade. You can also read the winning essays in each of our contests, as chosen by expert judging panels, here

Compilation volumes containing expanded versions of the winning essays from some of our most recent contests are also available for purchase.

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