This blog post series is a paraphrased version of a conversation I had with accelerator physicist Pat Karns (pictured, not to scale), who provided me with Actual Knowledge while I was writing my new book, Scharlette Doesn’t Matter and Goes Time Travelling. There’s no doubt that Scharlette is full of made-up nonsense, but I did ‘kinda’ want to stay ‘semi-accurate’ in ‘at least’ ‘some areas’.
Pat seemed like a good fellow to ask about the universe. He works at Fermilab making particle beams (that’s right) to be used in experiments which try to answer fundamental questions about what we’re all made of, how it came to be, and how it all fits together. It is his job to conjure up particles (my words) and then send them as really fast down a chain of accelerators in order to slam them into things (his words).
Who wouldn’t want to ask a guy like that a bunch of questions?
First I wanted to find out about the Heat Death of the Universe. In the book, Scharlette meets Tomothy, a time travelling agent from a distant future called ‘the Death’. This is short for ‘the Heat of the Universe’, a theory which explains one of the (many, fun) possible ways the universe may end. Tomothy and his people float about in Heat Death in a space station imported from the past, and I wanted to find out about what that might entail.
1. What is Heat Death?
SAM: Hi Pat, and welcome to a highly edited version of our email exchange, which did not originally begin like this.
PAT: Thank you.
SAM: Thank YOU. Okay, so the Heat Death of the Universe – can you break it down a little?
PAT: Right, well, whatever direction we look in from Earth, all matter seems to be moving away from us. So either we’re the smelly kid from school who no one wants to be around, or the universe is expanding. The exception is things caught in the gravity wells of black holes, which are so dense that even light can’t escape them. Anything caught by these, like Earth will likely be one day, will get squeezed together into a space the size of a drop of water. I know that sounds depressing, but there’s hope.
SAM: Oh? What’s the hope?
PAT: No more traffic jams. Anyway, after everything has been sucked into black holes, the black holes themselves will lose energy and evaporate. This process involves spontaneous particle pair production.
SAM: That old chestnut.
PAT: You see, every once in a while, a pair of particles gets spontaneously created – a particle and its antiparticle. Usually, the amount of energy used when they are created is recovered when they annihilate each other.
SAM: Like with marriage?
PAT: Exactly. But what if a pair of particles gets created on the event horizon of a black hole? One particle gets sucked into the hole, while the other goes outwards, and away. The energy that gets lost when these particles don’t annihilate is also lost from the black hole. So, as time goes by, the black hole will get smaller and smaller, and the particles that escape will continue to move farther away.
SAM: And once this happens all over the universe …
PAT: Particles will take increasingly long times to find other particles to interact with. The universe will become cold, near absolute zero, and pitch black because there’s no more stars, and not much of anything beside some rare hydrogen and a bunch of fleeting quarks and electrons all scattering away. That’s what’s meant by the Heat Death of the Universe – or, to reorder the words a bit, the ‘death of heat’.
SAM: Well, book me a ticket.
PAT: You’re going to need a really good space heater.
SAM: Which actually brings me to my next question …
2. Getting Around in Heat Death
SAM: So in Scharlette, humanity has used a time travelling space station called Panoptica to flee into Heat Death because, ‘from this unique vantage, Panopticians would be charged with ensuring humanity’s survival, and making sure that no other race ever developed time travel.’ Basically, since they live at the end of the universe, and everything has already happened, they can rule forever and no one else can screw with them. The question is, is it hypothetically possible to survive in Heat Death? If I had a space station like Panoptica, and could import supplies and food from the past as needed, could I remain there indefinitely? Basically, would I be okay if I brought a packed lunch?
PAT: Yes, bring a flashlight too, and an extra sweater. You’ll have nothing to draw energy from though, no light, no radio waves (bring your iPod), and certainly no McDonald’s drive-thru so you better be prepared. If your time travellers were able to create a Dyson’s Sphere, and bring a sun with them, they’d have a billion years of power, depending on what model iphones they had. Of course, removing matter from the past would make Heat Death occur earlier.
SAM: Wait, what?
PAT: The more matter you take with you into Heat Death, the less further you have to go into the future to get there.
SAM: So, okay – the more matter you ‘import’ from the past, the faster heat death will occur? What a great idea, I’m totally gonna pinch it. (Note: I totally did.) It nicely supports some of the themes developing via the different ideologies of people at the station – there are those amongst them who feel the station is an environmental threat to the past, and this would certainly be borne out if its existence led to the end of countless alien civilisations years before they were originally destined to finish.
PAT: Do keep in mind the scale of things when I talk about pulling matter into the future. If you’re just pulling an asteroid or two, no one will ever notice. The percentage of total matter that represents is laughably small. But it’s also pretty unlikely that such a small amount of matter would really help fuel Panoptica. Bringing in a planet, or a star, or even a whole solar system would likely go unnoticed by anyone except those who lived there (imagine being on the ISS when Earth suddenly disappears from beneath you). It’s possible that pulling a galaxy is the kind of scale needed to have an effect on Heat Death, but even then it would be a small one. Once you start pulling in clusters of galaxies, you’ll really start getting the attention of the universe.
SAM: I still reckon it could still be a real concern for the characters, given Panoptica could potentially go on existing forever with an expanding population, if it kept pulling in matter. But anyway, before we get too far ahead of ourselves, ha ha …
3. How Long Until Death?
SAM: … when is Heat Death actually estimated to occur? I can’t seem to find this number easily online, and even a broad range would be helpful.
PAT: So I ran the numbers and it looks like Heat Death will occur the Tuesday after next, so I’ve gotten my taxes done just in time. Oh wait, I forgot to carry the 1 billion, that’ll push it back a bit. The current estimates I can find, based on what we currently think we know of the universe, is that Heat Death will occur in around 10^100 years. If you’re not familiar with the notation, that’s 10 times 10 a hundred times, which is a really big number.
SAM: So if a Panoptician was going to describe their current year, they might say something like 100000000000000000000etcetc AD.
PAT: There would be a lot more zeroes and etceteras.
SAM: Okay, how about this – say a Panoptician needs to tell someone from the present day how far in the future they come from? Is there a more general way of expressing it as a number that I can get away with, i.e. ‘I am from billions of years in the future’ or ‘trillions of years’? Would I be right in saying that a Heat Death future exists somewhere between ‘a septendecillion years in the future’ and ‘a vigintillion years in the future’? Or are we in googol territory? Basically I just want to make sure I’m referencing the right massive numbers when characters talk about it in casual conversation. I guess it WOULD be correct to say ‘trillions of years into the future’, just as it would be technically correct to say ‘many, many decades into the future’, and yet I’m looking for the most accurate word to express how long has gone by.
PAT: We’re looking on the googol scale here. Well maybe, but quick question for you – are you using the long or the short scale?
PAT: Is a trillion 10^12 or 10^18 for you?
PAT: I’m familiar with the short scale, but I’m thinking you use the long scale.
PAT: In which case then yeah, the timeline for Panoptica would be between a septendecillion and vigintillion years.
SAM: Hmm. Not exactly snappy.
Note: In the end, years in Panoptica’s calendar are expressed as AHD, as in ‘After Heat Death’, counted from the station’s own moment of arrival. For example, ‘Tomothy was born in 215AHD’. As for the other issue, I pretty much just dodged it.
SAM: Thanks for taking the time, Pat.
PAT: Let me know if there’s anything else. I can always consult with one of my colleagues, I can’t throw a rock around here without hitting an astrophysicist.
SAM: Don’t throw rocks at astrophysicists, they just go into orbit around them.
END OF #1
Scharlette Doesn’t Matter and Goes Time Travelling is out now, depending on your temporal location.
Or read the exciting final instalment, Chat with Pat #2: Is There Any Such Thing as Randomness?