The Very Large And The Very Small–Part 2

Brane-brane-strings2012-Massey-Turok-cover(Part 1 here. Hover over images for attribution.) In M-theory there are things called branes. A 0-dimensional brane is a point, a 1-dimensional brane is a string, a 2-dimensional brane is a membrane, a 3-dimensional brane is a space, etcetera. Branes separate dimensions. M-theory has 10+1=11 dimensions–ten dimensions plus time. We live in three of those dimensions (plus time), but there are seven others. The ‘world’ is a 10-dimensional brane with the other branes inside it. Detecting other dimensions indirectly is theoretically possible. There are open-ended strings and closed-loop strings. The loose ends of open-ended strings are tied down to their space and so the string cannot cross into another space–what happens in x-y-z stays in x-y-z. But a closed-loop string, such as those that make up gravity, is not tied down to any one space, but can be detected in other spaces.

LISA-wavesThat’s the theory, anyway, and it is relevant to detecting the Big Bang itself. The satellites mentioned before–COBE, WMAP, and Planck–all detect electro-magnetic radiation, which includes light; however, they can’t detect electro-magnetic radiation in the opaque, earliest universe (the universe in its first 300,000 years). Perhaps, though, we can detect gravitational waves from the earliest universe, according to some models. The proposed set of satellites known as eLISA (evolved Laser Interferometer Space Antenna–‘evolved’ I think because ‘on April 8, 2011, NASA announced that it would likely be unable to continue its LISA [pictured] partnership with the European Space Agency, due to funding limitations’) is designed to detect gravitational waves, including those from the Big Bang and possibly from other dimensions. There are other experiments designed to detect gravitational waves, and Turok is 100% certain that we will detect them ‘in the next ten years’ (he said in 2008). When we can, ‘this will be a new window on the universe’, even the earliest universe, right to the Big Bang.

Big bang manifoldIn 1999, Turok and Steinhardt wondered what happened when two branes banged into each other. Could it happen again? Added to Einstein’s equations, the Big Bang does not collapse to a singularity, but to a membrane. This bang, this collision, ‘is the Big Bang for all intents and purposes.’ It could happen again, many times, hence the ‘cyclic model’. In the cyclic model, the collision was gentle, happening over billions or even trillions of years and did not generate gravitational waves, whereas in the standard view, the Big Bang happened all at once in a furious and sudden explosion and generated gravitational waves that should be detectable today. So if we do detect gravitational waves from the Big Bang, this disproves the cyclic model and supports the standard view.

Brane and dark matterOur space has light and such, and its mirror space has ‘other stuff’. The two spaces are separated by branes, but connected by gravity, which offers all kinds of exciting possibilities, such as ‘dark matter might be the matter on the other brane.’ Although its mass is not directly evidenced, its gravity deforms our space. ‘It’s really hard to test,’ said Turok. ‘We can’t make dark matter in the laboratory.’ M-theory is this marvellous theory which cannot be tested. ‘That’s all the more reason, I believe,’ he said, ‘to study the Big Bang. We know the Big Bang happened, we can measure the outcome.’ Turok said that this theory may be proven wrong. He has worked before on theories before that have been proven wrong. Having theories which can be proven wrong is good science, he said, and ‘I think one should be humble in the face of the universe.’

Universe expansionWhat’s this got to do with social justice? To begin with, it’s a lesson in scale–strings are teeny; the universe is huge; time goes on and on; life as we know it happens somewhere in the middle. ‘The arc of the universe is long, and it bends towards justice,’ said Martin Luther King. Long, way past peak oil, until our story aligns with the universe story, until we learn to live within our limits, until our law is wild law, until the problem and the joy are one (again)–that’s a unified field theory to look forward to. And, as Brian Greene said, ‘it’s what we do’: finding out, being curious. The more you find out, the more you love. And the more you love, the more you care. And the more you care…. (Continued in Part 3)

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