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This Is What We Don’t Know About The Universe
In recent days I’ve had some interesting conversations. There’s a giddiness going around, related to an outpouring of science love – the kind you get from President Obama introducing TV science shows, the kind that has wonderful visuals, but is, well, a wee bit simplistic (a sin that none of us could ever, ever be [...]
- By Caleb A. Scharf on March 12, 2014
- 24
This Is What We Don’t Know About The Universe
In recent days I’ve had some interesting conversations. There’s a giddiness going around, related to an outpouring of science love – the kind you get from President Obama introducing TV science shows, the kind that has wonderful visuals, but is, well, a wee bit simplistic (a sin that none of us could ever, ever be [...]
- By Caleb A. Scharf on March 12, 2014
- 24
You may experience some temporary disillusionment
In recent days I've had some interesting conversations. There's a giddiness going around, related to an outpouring of science love - the kind you get from President Obama introducing TV science shows, the kind that has wonderful visuals, but is, well, a wee bit simplistic (a sin that none of us could ever, ever be accused of, naturally). It's all very positive, commendable, and perfectly reasonable. But it leaves me feeling a little askew. You see, the thing is, it's relatively easy to focus on what we know, yet to me the wonder of the cosmos, the awesomeness, is never greater than when we contemplate all that we don't know.
It's true that when we take note of the impossibly brief sliver of time that our entire species has inhabited compared to the billions of years before, and the untold billions ahead, one can feel refreshingly small. Or, if we contemplate the billions of trillions of other worlds that must exist across the observable universe, we can grasp momentarily at just how tiny our daily existence is. But for me nothing compares to the perspective, the shock, or the excitement, of being reminded of what we don't know.
We don't know why the universe exists: This is really quite unfair, and could be grounds for doubting that the cosmos knows what its doing. But in terms of physics, although there are some really very appealing, very promising, theoretical frameworks that begin to answer the question, the simple truth is that we're not sure which might be right. It may be that the universe springs from an inherently unstable 'nothingness'. The most void-like void, prone to spontaneous generation of matter and energy in proportions that always balance out to zero (yep, really, read Lawrence Krauss's great book on this). Furthermore, this may not be the only universe (a terrible linguistic fail, I know), but rather one of a vast array, part of a multiverse of more than 10 to the power of 10 to the power of 16 distinguishable realities. But a big piece of the problem is that we're still waiting for the next generation of cosmic measurements to chip away at the models, and we're still waiting for theories that provide more readily testable hypotheses, not just mathematical elegance. So we don't know why the heck all of this exists. Sorry.
We don't know what dark matter, or dark energy, is: Big problem, honking big problem. Normal matter, the stuff of you, the stuff of me, planets, stars, and cheese sandwiches, amounts to only about 4.9% of the total matter and energy content of the universe. 26.8% of matter is 'dark', we know it's there because on large, cosmic, scales stuff moves around faster than it should and because the way that galaxies strew themselves across space is consistent with the existence of vast amounts of slow-moving gravitating 'stuff' that never turns into stars or planets or anything, just stays as diffuse, invisible, incredibly antisocial particles. Except we really have no idea what these particles truly are - a situation beautifully summarized recently by Mario Livio and Joe Silk. That's nasty, but perhaps nastier is dark energy. Something is causing the expansion of the universe to accelerate. It didn't used to. Until about 5 or 6 billion years ago the stretching of space following the Big Bang was in decline, but then something started to counter that, another unseen component, perhaps a type of vacuum energy density that fills up space as space itself grows. What exactly is it? We do not know. We have lots of ideas though, which is great, always good to have ideas about 68.3% of the universe.
We don't know whether life exists anywhere else: This one is close to my heart. Here we are, sentient beings on a planet seething with life (although perhaps not as seething as it could be) that's been busy sculpting and re-sculpting the physical and chemical environment for much of the past 5 billion years. And now we're confident that there are lots of planets out there, and that many of them could have an equal shot at playing host to life. But we still don't know whether or not we're alone. No clue. That's quite a problem. Don't get me wrong, it's a good problem, a juicy problem, one of the best. But even when the President of the United States introduces a lovely glossy TV series all about science, science that addresses the question of life in the universe, that doesn't mean that governments or industry give a fig about paying to solve the problem. As Lee Billings writes in his recent, wonderful, book, the lack of a sense of urgency is a little bewildering. So we continue to bumble along in splendid isolation, with only our towels for comfort.
We probably haven't really figured out the quantum world: What!? While it's true that our present mathematical framework of quantum mechanics can do wonders, from describing atoms and molecules to the bizarre nature of entanglement and qubits, that doesn't mean that we've nailed the case shut. Quite the contrary. One need only cast a look over the literature to see that the most fundamental aspects of the quantum nature of the universe are still causing headaches and disagreements. People are still reformulating the ways in which we cope with the quantum nature of reality (yes, they are) so it's clearly too soon to call this fully understood. Not only that, but the possibility of pure quantum effects reaching into the realm of soft, wet, and warm biology has also raised its head (although admittedly it depends on who's talking) - a rather unnerving notion. . Oh, and don't get me started on black holes and quantum firewalls...
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