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It's the 365 days of Astronomy PodGa, coming in 3, 2, 1.
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Hi, this is Steve Nellick.
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Why, why, why, why, why, why?
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Why, why, cheap astronomy, oh me?
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And this is D-cheap astronomy, episode 131, what's the point?
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But we are yet to determine how it is that we're here,
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let alone determine the point of why we're here.
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Although we do think there is at least one point.
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D-cheap astronomy, did the universe really start from a single point?
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This hypothetical concept is commonly stated in popular science articles
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and we are guilty of doing the same here at cheap astronomy.
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However, it's not necessarily correct.
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As with most things relating to the universe,
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all we can really talk about is the observable universe.
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All evidence we have available does suggest that the observable universe
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emerged from a single point 13.8 billion years ago.
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But if the whole universe is bigger than the observable universe,
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which it very likely is, then it's not clear whether the whole universe
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emerged from that point.
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Of course, it could have, if in some fraction of the first second,
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cosmic inflation pushed the proto-universe out to distances
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that we neither can nor will ever be able to observe.
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This gives some credence to a belief that the unobservable universe
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could be equivalent in nature and consistency to our observable universe,
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which is fairly homogenous and samey up to the limits of our observation.
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But it is best just to call that a belief.
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There's no way to confirm anything we may choose to assume
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about the unobservable parts of the universe.
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Nonetheless, the current consensus working model is that the observable
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and unobservable universe did emerge from the same point 13.8 billion years ago.
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No one's disproved this yet, so it's what we're choosing to run with for now.
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It can't say where that point was when it all started,
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since it popped out of nothing and nowhere and nothing and nowhere
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does not have a coordinate system to identify locations.
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The idea of a universe appearing out of nowhere may seem extraordinary,
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but it's perhaps less extraordinary than a universe having been around
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Things should have beginnings,
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and when you were talking about the beginning of everything,
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it does sort of make sense that before there was everything,
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there must have been nothing.
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What else could everything have started from?
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But as to a causal mechanism, that's still a long way off.
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Current thinking varies widely, but for example,
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it might be the case that potential universes pop out of nothing
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on a regular basis and last for varying durations.
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All assuming that each such pop of a potential universe
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involves a rapid expansion of space time,
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meaning that each potential universe will have a certain size and duration.
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We could also assume that each of those initial pops of space time
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contain a stupendous amount of energy,
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which begins to cool as the space time that contains it expands.
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The precise nature of that energy is not clear,
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which are saying energy in air quotes.
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But whatever it may be, things begin to freeze out of it as it cools.
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So you get leptons, such as electrons and neutrinos,
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and you get quarks, which towards the end of the first second
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mostly coalesced into protons and neutrons.
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And on top of all that, you presumably also get dark matter,
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which is whatever it is.
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Anyway, that is a story that fits our universe.
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Other universes may have different stories.
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For example, theoretically, our universe should have equal amounts of matter
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and antimatter, but at some early point in the proceedings,
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matter came to dominate.
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There's no consensus view on how or why this happened,
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and it does perhaps raise the possibility that while universes
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may pop out of nothing on a regular basis,
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if they do have balanced anti- and non-anti-contents,
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those contents will annihilate with each other.
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You'd only lose charged particles through that process,
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but that means you lose protons and electrons,
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so no atoms, no stars, no planets, and no beings.
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But since we know an imbalanced universe has happened at least once,
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it may be the case that imbalanced universes are more than normed in the exception,
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although it's pretty likely we'll never be able to confirm that.
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This is the middle bit.
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So the next time someone asks what's the point of us being here,
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you could just respond by saying that our presence is just one of a vast
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array of alternate possibilities that have quite possibly already happened.
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So, since we are here, why don't we try and stay here,
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rather than just becoming another failed attempt?
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Dear cheap astronomy is space-based solar power
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the solution to all our problems?
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Well, not all our problems,
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and while space-based solar power,
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SBSP is technically feasible,
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it may not be economically viable.
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The general idea of SBSP is that you have a solar collecting facility
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in Earth orbit, which then transmits the energy collected as microwaves
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down to the Earth's surface.
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Microwaves are preferred since they pass through the Earth's atmosphere relatively well,
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and should not harm aircraft, ground infrastructure, or people
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if they happen to get in the way.
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It might seem a bit daft to intercept light that can already pass through the atmosphere,
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convert it into a lower energy form of light, and then pass that through the atmosphere,
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pass the collection of solar energy in space as a lot of advantages over
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collect it on the ground.
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Firstly, passage through the atmosphere, scatters sunlight,
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and higher energy wavelengths in the ultraviolet just bounce straight off.
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A solar panel in space can generate two or three times more power
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than an equivalent solar panel on the Earth's surface.
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Also, you can collect solar energy in space for nearly 24 hours a day.
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Assuming your collector is in geosynchronous orbit,
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at nearly 36,000 kilometres altitude, Earth will really be directly between it and the Sun,
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so you can keep your collector eliminated for an average 99% of the time
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over the course of a full year.
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So, that all sounds great, but now here's the downside.
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Since we are talking about a microwave beam with a lower intensity than sunlight,
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you'll need a very wide beam to transmit a worthwhile amount of power to the surface.
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A transmitter aperture of around one kilometre in diameter is suggested.
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And since you are sending a 1 kilometre diameter microwave beam across a distance of 36,000 kilometres,
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with the last 10,000 kilometres being through Earth's atmosphere, the beam will spread.
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Meaning you need a much bigger receiving aperture on the ground,
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which might be 10 kilometres in diameter.
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That's some pretty serious infrastructure involving a substantial upfront investment,
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not to mention public opinion challenges, around fears of a death ray,
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plus no one really wanting a 10 kilometre wide microwave receiver in their backyard.
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This is where we say it's technically feasible but economically problematic,
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and there are actually bigger problems with the 1 kilometre space transmitter.
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Firstly, it represents a lot of mass to launch and get all the way out to geosynchronous orbit,
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and it's also a lot of infrastructure to maintain there.
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In geosynchronous orbit, above the Earth's magnetosphere, solar panel surfaces are quickly degraded by the solar wind,
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and micrometeor strikes on a 1 kilometre diameter surface area are going to be inevitable, if not frequent.
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Also, you are dealing with infrastructure which is designed to maximally capture radiation,
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and hence that infrastructure is going to get quite hot,
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and there's an inverse relationship between solar panel efficiency and how hot they are.
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You can deal with that by any cooling system,
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but really that's just a heat transfer system, you'd still have to get rid of the heat somewhere,
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perhaps through large surface area radiator panels.
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But of course, that's more mass, more structural complexity, and more points of potential failure.
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Nonetheless, in January 2023, Caltech's space solar power demonstrator was launched into low Earth orbit,
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aboard a SpaceX Falcon 9 rocket.
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The small satellite did demonstrate that components of a space-based solar power system could work in Earth orbit,
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and the unit did successfully transmit a tiny microwave signal back to Earth.
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So that confirms the technical feasibility, but the next step of scaling it up to a meaningfully productive,
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an economically viable system, is where all the question marks lie.
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The whole thing looks to be hugely expensive, and a cost-benefit analysis is difficult to undertake,
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until we actually build something to scale.
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So, we're not meaning to write the whole thing off as a bad idea,
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but the cost and uncertainties involved in implementing a working system
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mean that it's not going to happen anytime soon.
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There is a commitment from several government agencies
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to further develop small-scale trials,
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which is probably the best way forward for now.
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This is the end bit.
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A solution to all our problems is in plain sight, although please don't go staring at the sun.
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Nonetheless, that solution to all our problems is about as technically difficult to achieve
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as the other solution to all our problems, economically viable, nuclear fusion.
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It's hard to say if either option will eventually work out,
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but if we are looking for some point for us being here,
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it's probably for us to keep on being here.
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But that's it for another episode of Dear Cheaper Astronomy.
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If you've got a space science question, or you just want to be,
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why not write to cheapastroatgmail.com
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and we'll connect the existential dots for you.
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Thanks for listening.
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Steve Nellick, Cheaper Astronomy.
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You're losing to 365 days of astronomy podcast.
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As we wrap up today's episode, we're looking forward to unraveling
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more stories from the universe.
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With every new discovery from ground-based and space-based observatories
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and each milestone and space exploration, we come closer to understanding
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the cosmos and our place within it.
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Until next time, let the stars guide your curiosity.