The nothing that is

Recent measurements... suggest that the universe as a whole has zero energy, zero charge, and zero angular momentum. How is this possible? All energy due to matter (which is positive) is canceled by an equal amount of gravitational energy (which is negative). There are equal amounts of positive and negative charge, and we cannot create one without creating the other. Zero angular momentum means that the universe has no net spin. The universe, then, is a whole lot of nothing: yin and yang that cancel each other out. Locally, in our own neighborhood, we seem to have lots of stuff: matter, charges, motion, entropy, and uncertainty. But globally, none of these exist, never have and never will.

-- from The Rise of the Uncertain by Vlatko Vedral at Nautilus

Plato's universe

 John Wheeler said that the "basis of all mathematics is 0 = 0". All mathematical structures can be derived from something called "the empty set", the set that contains no elements. Say this set corresponds to zero; you can then define the number 1 as the set that contains only the empty set, 2 as the set containing the sets corresponding to 0 and 1, and so on. Keep nesting the nothingness like invisible Russian dolls and eventually all of mathematics appears...

...Reality may come down to mathematics, but mathematics comes down to nothing at all.

That may be the ultimate clue to existence - after all, a universe made of nothing doesn't require an explanation. Indeed, mathematical structures don't seem to require a physical origin at all. "A dodecahedron was never created," says Max Tegmark.

"To be created, something first has to not exist in space or time and then exist." A dodecahedron doesn't exist in space or time at all, he says - it exists independently of them. "Space and time themselves are contained within larger mathematical structures," he adds. These structures just exist; they can't be created or destroyed.

That raises a big question: why is the universe only made of some of the available mathematics? "There's a lot of math out there,"  says Brian Greene. "Today only a tiny sliver of it has a realisation in the physical world...

..."I believe that physical existence and mathematical existence are the same, so any structure that exists mathematically is also real," says Tegmark.

So what about the mathematics our universe doesn't use? "Other mathematical structures correspond to other universes," Tegmark says. He calls this the "level 4 multiverse", and it is far stranger than the multiverses that cosmologists often discuss. Their common-or-garden multiverses are governed by the same basic mathematical rules as our universe, but Tegmark's level 4 multiverse operates with completely different mathematics.

-- from Reality: Is Everything Made of Numbers? by Amanda Gefter

It's very hard to imagine all the crazy things that things really are like

Dark materials

...any hopes that the nature of [dark matter] would be quickly revealed by these first detections have been utterly dashed. The trouble is that dark matter appears to be different things to different detectors. It appears heavier in one detector than another; it appears more ready to interact in one experiment than another. In the most extreme case, it shows up in one instrument but not in another - even when both are made of identical material and are sitting virtually next door in the same underground lab...

-- from Dark matter mysteries

A hitchhiker's guide to the multiverse

Different theories spin off very different kinds of multiverses. Our current standard theory of how the universe came to be, for example, predicts an infinite expanse of other universes, including an infinite number in which duplicates of you are reading this sentence and wondering if those other versions of you really exist. Meanwhile, string theory, which hoped to derive the particles, forces and constants of our universe from fundamental principles, instead discovered a wilderness of 10^500 universes fundamentally different from ours. Even quantum mechanics implies that our universe is a single snowflake in a blizzard of parallel universes.

-- from The Ultimate Guide to the Multiverse.

'Temple of the winds'

Interesting section in Jim Al-Khalili's Hearing the Past, starting about 9 minutes 30 secs in, on the acoustic characteristics of Stonehenge. And he quotes from Hardy in Tess:

The wind playing upon the edifice produced a booming tune, like the note of some gigantic one stringed harp.

Some of the work by Rupert Till et al is explored at Sounds of Stonehenge.

Perhaps archaeoacoustics will, one day, inform an even broader 'archaeology of the senses' in which the deep history of other senses including smell is even better understood.


P.S. 20 Sep: Bill Fontana wants to bring sounds of Chesil Beach to central London.

P.P.S. 17 Feb '12: Did otherworldy music inspire Stonehenge?

A tiny drop

Spinning water droplets that behave like black holes look (to my untrained eye at least) like an example of how the very small may join to the very large. As a drop spins, it progresses through what seem to be almost Platonic shapes, starting with triangle, square and pentagon -- presumably reaching circle at the highest speeds.

Almost everything

In Surfing the Universe, Benjamin Wallace-Wells surveys the controversy over Garrett Lisi's work. Towards the end Wallace-Wells quotes Betram Kostant of MIT who is "unaffiliated in the string theory wars":

Columbus made mistakes and thought he was in India. [Garrett] Lisi made a few errors, but this pales into insignificance to his possibly opening up a whole new world for exploration...E* is like North America, South America, and the Pacific Ocean all rolled into one. No one in Europe knew anything about it...Lisi's daring possibly creates an agenda for scientists for the next hundred years or more.

P.S. 24 July: Vaguely relevant may be Roger Penrose and Keith Tyson on the limits of reason.

One more

I do not know how useful or true this is, but it is beautiful.