How can a “big rip” tear the universe apart? What does that mean for existence itself? Is it going to happen, and what are we doing to find out? I discuss these questions and more in today’s Ask a Spaceman!

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EPISODE TRANSCRIPTION (AUTO GENERATED)

What are we supposed to do when nature is telling us that something is happening that should be impossible? And I mean outright impossible, not just weird or strange or unexpected. And I don't mean nature telling us as in the evidence is shaky or contradictory or circumstantial, like something your best friend's cousin's former roommates. And, no, I'm talking about decades of work using the most sophisticated tools, the most advanced statistics, a combination of different measurements, all leading to the conclusion that the universe might just be doing something utterly impossible. And no, I'm not talking about dark matter.

Dark matter dark matter is weird and mysterious for sure, but it's not impossible. To explain dark matter, you just need new ingredients in the universe that don't interact with light, and we know of lots of those kinds of particles already. So that's, like, kinda no big deal, except we don't know what dark matter is, but that's a different episode. And, no, I'm not talking about dark energy either, at least not at first. Dark energy is just the name we give to the accelerated expansion of the universe, which is weird and mysterious, but not outright impossible.

It's perfectly allowed in the equations of general relativity to have accelerated expansion. So it's fine. Everything we know about physics is compatible with the existence of dark matter and dark energy. But as we make ever more careful measurements of dark energy, we keep running into this impossibility. And the possibility of it, and I will stress that at this stage, it's only a possibility that this effect is real.

We have the possibility that dark energy is doing something impossible. It's possibly impossible. I like that. Okay. Before we dig into the possibly impossible thing, the thing that shouldn't be happening but just might actually be happening, we need to go over the measurement.

We need to talk about how we measure this. How do we even know what it is we're talking about? How do we go about measuring something like dark energy and getting a handle on it? I mean, I need to start off with a statement that we have no idea what dark energy is. It's the name we give to the accelerated expansion of the universe, and, just hold on.

I'm checking my notes here. Yeah. That's about it. That's all we've got. The expansion of the universe is accelerating.

We don't know why. We don't know how. We give it a cool name, though, dark energy. I mean, of course, we have a long list of theoretical ideas of what dark energy could be, of which most of those ideas are terrible, and some of them are merely awful. We have no good ideas about what dark energy is, but we are still faced with the unignorable observational reality that the expansion of the universe is accelerating.

So as we attempt to grapple with this, we can approach dark energy by attempting to model it. Some of the models may come from a physical idea or theory or insight. You're like, oh, there's this weird quantum field, and it behaves this way. And and therefore, dark energy manifests in this way, and then this is how I'm going to approach it. Or you can approach it a model constructing a model of the behavior of dark energy just as a set of handy mathematical equations to at least write down the problem.

Like, we have this accelerated expansion. We can describe the accelerated expansion, and we can craft a fake pretend model for that accelerated expansion independently of our knowledge of dark energy. And the hope is that by constructing this model, we can start measuring and testing this model, then we might be able to get a handle on what dark energy actually is. We can get some, hooks into a deeper physical insight if we just start with this is what's called phenomenology. I'm just looking at the phenomenon, and I'm trying to model that with some mathematical expression.

So, like, a metaphor here. Let's say you're at a party, and there's a room with lots of food out on the table, the food room, my favorite room at every party, and there's a plate of cheese, and it's a great cheese spread. It's gorgeous. Got lots of variety. This is this is a really rocking party, at least according to me.

And you check on that cheese. You walk into the room every once in a while, and you notice that the cheese is is going away. Right? Like, as time passes, more and more cheese disappears. There's less and less cheese available on the plate.

And you're curious who or what is eating the cheese? So on one hand, you have this observational reality. The cheese is disappearing. You have some potential motivated models. Maybe it's your uncle that's taking all the cheese.

Maybe it's the kids. Maybe it's the dog. Maybe little ants are crawling on the table and picking up pieces of cheese and and crawling away. You have all these options and you have no idea which idea is right. You have no clue which theory hypothesis could be on the right track or not.

And it's getting pretty exhausting to come up with models of your uncle taking the cheese, and the dog's taking the cheese, and the kids taking the cheese. And so you skip it. Instead, you just create a mathematical model of the phenomenon of the cheese disappearing. You know, there is less cheese with time. So there is a cheese disappearance rate that you can measure, that you can create.

You have this mathematical model based purely on phenomenology, the observed reality of disappearing cheese. You are going to create a mathematical model of the rate of cheese disappearance. And then you hope that by studying this cheese disappearance rate, you might get some clue as to who's responsible. So for example, if the cheese, this is, I'm really beating this metaphor into the ground, aren't I? If I measure a very slow cheese disappearance rate, then, probably, it's not your uncle who you know is a huge cheese eater and just just gonna grab handfuls at a time.

So you can probably rule that model out. If a lot of cheese if your cheese disappearance rate is very very high, you can probably rule out a tiny little ants, because presumably, ants are only going to take a little bit of cheese at a time. And so by measuring this phenomenon, you hope that you can start trimming you can start pruning your theories, and this is a very common strategy in science. When we encounter something that we've never encountered before and we don't even have a good handle on it, we can at least start measuring its properties, and then from there, hopefully, winnow down some decent theories. Dark energy is the disappearing cheese of the universe in what is perhaps the worst metaphor I've ever constructed on this show.

We see the accelerated expansion. We guess that there is something powering this expansion, that there is some ingredient in the universe that is driving the accelerated expansion of the cosmos. Whatever this thing is, whatever this entity, whatever this driver is, it's filling up the entire universe because the accelerated expansion is having happening everywhere simultaneously. So we know, or we're going to make a guess, that the expansion of the universe is caused by some entity, something, and we're going to make a pretend model of that thing, the eater of the cheese, the driver of the expansion. We're going to make a pretend model.

This model is not physically motivated. It doesn't come from, like, quantum mechanics or general relativity. It's just a model to describe the observed behavior. We pretend, and if I could speak in italics, I would, we pretend that dark energy is some kind of substance, a fluid, actually, that invisibly fills up the entire universe. This substance, this fluid, this dark energy thing is going to be the driver of accelerated expansion.

There is some physical mechanism, which we do not know or understand, that causes this fluid, this substance to drive the accelerated expansion. We don't know what it is or how it works, but we can measure its properties. Right? If I'm taking my cheese metaphor all the way, I have I can measure, like, disappearance of cheese as a function of time. I can create a hypothetical cheese eater, a model of a cheese eater who is taking all the cheese.

And then from there, once I have this very general model of cheese eaters, I'm going to assume that the cheese is being eaten, and that's why it's disappearing. And I'm going to measure the rate of cheese disappearance, and I'm going to see which, you know, which actual culprits might fit the bill for that hypothetical cheese eater. So I have this mysterious substance. I don't know what it is. I don't know the the true physics underlying it, but I I'm going to guess that there is some sort of substance.

This fluid, this stuff fills every nook and cranny of the universe. When you walk down the street, you're actually swimming through a little bit of dark energy. Again, this is just a temporary placeholder model to allow us to study dark energy without quite knowing what it is. This dark energy substance or fluid that fills up the universe is the cheese ghost that's eating all the cheese. And then hopefully someday, once we really understand this cheese ghost, we can understand who's actually eating the cheese.

Maybe if we measure this pretended dark energy stuff well enough, we can replace it someday with a physical theory. Now fluids, like all stuff, have certain properties that we care about. Fluids have pressure, fluids have density, fluids have inertia, viscosity, so on. Just like water or oil or air, dark energy, this fluid, this substance that we are pretending exists in the universe and that is driving accelerated expansion, has properties too. It has pressure.

It has density, inertia, viscosity. We can assign all these properties to it just like we can assign to our hypothetical cheese ghost, our hypothetical cheese eater. We can assign, height, weight, appetite. We can create this model of a cheese eater. We can create a model of a substance that is driving accelerated expansion.

Now often in physics, we're able to tie these properties of any substance together using what's called an equation of state. These are simple mathematical descriptions that connect one property of a fluid or a substance to another. You've actually encountered this before in your life, believe it or not. Do you remember, probably not, the famous ideal gas law that you learned about in high school chemistry? You know, PV equals nRT, pressure times volume, is proportional to the temperature.

That is an equation of state. It tells us that the pressure and the volume and the temperature of an ideal gas are all connected together and how they're connected together. Okay. This is just we're building out the properties of our cheese ghost, our our hypothetical cheese eater of the universe that's driving accelerated expansion. We pretend it's a fluid.

We pretend it fills up the universe. We pretend it has useful properties like pressure, like density. It turns out that for pretend fluids that span the entire universe and just might determine the ultimate fate of the cosmos, we really like to know its equation of state that describes the ratio of its pressure to its density. That's it. We're just gonna take this hypothetical fluid, and we're going to divide its pressure by its density.

Why do we do this in particular? Because that ratio boils down to a single number that we can go out and measure in the real universe, and it captures a whole lot of different approaches and theories and ideas when it comes to dark energy. That's cool. By pretending that dark energy is a fluid, we now have a simple number that we can try to measure, and different kinds of theories and ideas will predict different values for this number. This number is often denoted by w.

I don't know why. It is called the equation of state parameter of dark energy, which is quite a bit mouthful, which is why we just stick to w. It is the ratio of the pressure to the density of this hypothetical dark energy fluid. And we use this number for two reasons. 1, is that we can actually measure.

We can concot observations and experiments. I will not get into the actual observations today. Feel free to ask if you want. That can give us this equation of state parameter, this w. We can actually measure it, which is pretty cool.

So there's something we can observe, and different actual theories of dark energy, different physically motivated models. If you come up with some model of dark energy, you can express what its equation of state parameter should be, or the range of allowed values of its equation of state parameter. So that this allows us to go out into the universe, measure the equation of state parameter, this w, and then we can compare. We can say, okay, theory a, you're still in Theory b, you're still in. Theory c, sorry.

You've been knocked out. Better luck next time. Theory d, you're right on the edge. We're gonna see what the next round of measurements give us, etcetera, etcetera, etcetera. The equation of state parameter is something like the rate of cheese disappearance.

This is something you can go out in the universe and measure. You can just stand there with a stopwatch, check the room every few minutes, take a measurement, weigh the cheese, you know, measure you know, you can calculate that rate. That is a number you can measure, and then you have different models of culprits of who might be eating all the cheese, and then you can decide which ideas still work and which have been rolled out. For example, an equation of state parameter that equals negative one, that corresponds to something we call a cosmological constant. This is the case where dark energy is basically just a fact of life.

It is a number baked into the existence of the universe, the same as, like, the mass of the electron or the speed of light. It's just a fundamental number, and it just exists. And the expansion of the universe just stays the same, forever. And why the minus one is just the way the math worked out. W of minus one means cosmological constant.

So we go out and try to measure w, this equation of state parameter. And if it's something other than minus 1, then we know there's something interesting happening in our cosmos, that there's more than just a cosmological constant. And it's interesting when we go out with our probes and our missions and our statistics and our methods, we find a measurement of w that is totally compatible with the cosmological constant. It's actually roughly negative one, but not quite. The current latest combined measurements from all sorts of cosmological probes, again, happy to do an episode on what those measurements are.

Feel free to ask. Our current number within uncertainty on this w, this equation of state parameter is negative 1.013 plus or minus 0.03, which is interesting. With that level of uncertainty, it definitely includes the cosmological constant. It includes, like, the simplest kind of accelerated expansion, which is just accelerated expansion is a fact of life. But the preferred value is slightly more negative than that.

In fact, in the whole history of measuring w, this equation of state parameter, almost 2 decades now, the preference in measurements has almost always been for the equation of state to be less than minus 1. This is interesting. Remember, we don't have a physical model of dark energy yet. The simplest kind of dark energy is minus 1, and anything different than minus 1 means dark energy is more complicated than that. What does it mean for w to be less than minus 1?

Well, because the value of w, this equation of state parameter is so deeply connected to the expansion rate itself. We can simply plug in this number into the math and see where it takes us. If we have an imaginary fluid again, pretend imaginary fluid that fills up the universe is driving accelerated expansion. The way it drives accelerated expansion is governed by this equation of state parameter. So if you can you can tune the throttle on this w parameter, and you get different kinds of expansion histories of the universe.

Again, we don't know how it actually works or what's actually driving it, but we do know that there is this relationship. So we just plug it in and see what happens in in a pretty. And I didn't mean for this month to be a disaster end of the world end of the universe month, but I guess it is. I I picked these two topics totally independently of each other, and then now that I'm recording, my second episode of the month, I said, oh, last time I did, giant asteroids striking the earth and killing us all. And now I'm talking about the end of the universe.

And we need to take a quick pause so that I can let you know that this show is sponsored by BetterHelp. You know, we've talked a lot about time in this series. What is the nature of time? There's all sorts of physics concepts that we explore about the nature of time, but there's also this human part of time or the experience of time that we all know so intimately, and yet we don't understand. And one of the biggest things about time is that we all wish we had more of it.

Like, if there's an extra hour in the day or if we could just put things on pause, what would we do? I'd probably do more episodes. I don't know. But, like, we all wish that time was different. And one of the coolest things about therapy that I've seen in my own experience is that, you know, by realigning your perspectives, by realigning your expectations, you can get a better sense of your own flow of time.

So that time does its thing outside of our control, but you can be a part of that flow. If you're thinking of starting therapy, give BetterHelp a try. It's entirely online. It's convenient, flexible, suited to your schedule. Fill out a brief questionnaire and boom, you're connected to a licensed therapist.

You're done. Visitbetterhelp.com/spaceman today to get 10% off your 1st month. That's better help help.com/spaceman. This scenario of w less than minus one has a couple interesting names attached to it, and you might encounter both of them. 1 is called phantom energy, which is like dark energy, only more so, and the other is big rip, which is the consequence of what would happen in a phantom energy universe.

You see, with dark energy, dark energy is the name we give to the accelerated expansion of the universe. The universe is getting bigger and bigger, faster and faster every day. If that acceleration rate itself stays constant, that is a cosmological constant, that is a w of minus 1. If w is more negative than that, then the acceleration itself ramps up. So it's not just the expansion accelerates, but the acceleration accelerates.

It gets worse and worse and worse. In other words, the accelerated expansion of the universe just goes completely haywire. It goes out of control. Ironically, though, this makes our universe smaller. Check it out.

With accelerated expansion, objects get pulled away from each other faster and faster. Eventually, once objects are far enough away from each other, the expansion between them is faster than the speed of light, and that's totally fine. That's allowed, which and once the a distant galaxy crosses that threshold where it's receding away from us faster than the speed of light, then we will still see the galaxy because we're seeing the light that was emitted a long time ago, but then that galaxy will fade from view, it will redshift and then it will disappear. In an accelerated expansion universe, our observable bubble gets smaller and smaller and smaller. We see less and less with time.

This is already happening. We already see it with our present day universe. In a big rip universe, this process goes out of control. Because once 2 galaxies are receding away from each other faster than the speed of light, they are no longer in contact with each other. They cannot influence each other.

They cannot talk to each other. They cannot see each other. They are cut off. They they are in essentially different universes. They are in different observable patches of their of their own universe.

It's like being on the other side of a black hole. That's which is why we call it a cosmological horizon. That galaxy that has been ripped, torn away from us still exists, but it's in a closed off portion of the universe that we can never access again. In a big rip scenario, and, again, this happens normally in an expanding universe, in a dark energy universe, in a cosmological constant universe, it's just part of life of living in an expanding universe, but in the big rip scenario, this goes out of control. The expansion of the universe accelerates beyond belief, and our cosmological horizon rapidly shrinks.

So what we would see advancing into the future of a Big Rip universe would be galaxy after galaxy after galaxy simply getting plucked away from us, caught up in this out of control expansion. You know, once that out of control expansion gets its hands on a galaxy, it just takes it away. It gets worse. In the timeline of a Big Rip scenario, the future fate of the universe depends on the value of w, this equation of state parameter. The more negative it gets, the more out of control the universe becomes sooner.

So, for example, if we were to take an example of w equals minus 1a half, which is outside the bounds of current observations, so we don't need to worry about this exact scenario playing out, but roll with me here for illustrative purposes. If w were equal to negative one and a half, then we are living in the last chapter of the universe. We actually only have about 35000000000 years left in the entire history of the cosmos. Our universe has been around for roughly 14000000000 years. It's about 1 third of its age.

In a w of minus 1a half universe, a phantom energy universe, a big rip universe, what happens is everything gets torn apart. The horizons of the universe gets smaller and smaller and smaller. The scales at which 2 objects get ripped apart and caught up in this accelerated expansion just gets smaller and smaller and smaller. In a normal cosmological constant universe, a w of minus 1, a flat boring universe. Yeah.

There's still this happening. Your horizon is shrinking, but dark energy in that case, in a cosmological constant case isn't gonna touch galaxies. It isn't gonna touch groups. They they, clusters, anything like that. Anything that's gravitationally bound will stay gravitationally bound forever.

But in a big rip scenario, well, things get torn apart until you reach an event called the big rip, because about 34000000000 years from now, that's with 1000000000 years left to go, galaxy clusters get torn apart. Individual galaxies get flung away from each other even inside of clusters. At t minus 60000000 years, the Milky Way gets destroyed. You see a star on the other edge of the Milky Way? In a Big Rip scenario, that star gets plucked away from us, gets torn away from us, gets accelerated away from us faster than the speed of light.

It goes to live in its own universe. At t minus 3 months, our solar system gets ripped apart. You know what's left of it? The distance between here and Jupiter is so insignificant on cosmological scales. This might as well be nothing, but in a big rip scenario, Jupiter gets caught up in the accelerated expansion, and it gets torn away from us.

At t minus 30 minutes, the earth explodes. On one side of the earth gets removed from causal contact from the other side of the earth. It gets ripped apart. At t minus 19 seconds, atoms break apart. An electron can no longer be in causal contact with a neutron or a proton.

Atoms themselves get destroyed, and then comes oblivion, the destruction of space and time. All scales in space and time are removed from causal contact with each other. You can pick any two points no matter how close they are, Planck scale close, and they will be caught up in this accelerated expansion and torn apart. All causal connections all the way down to the Planck scale, the very fabric of space time itself losing all sense of regularity. And it is an end of the universe, at least as we understand it.

Yeah. Our understanding of the universe is grounded in space and time, being space and time. What if distances any two distances are always essentially infinitely far away from each other? It's like a reverse singularity where space and time instead of crunching down into an infinitely dense point just explode, leaving nothing in its wake. That's the big rip.

That's pretty grim, if a bit overdramatic. Obviously, w is not that negative. We know that already from measurements, and so the timeline isn't accurate. Given current constraints of what we know of w, that scenario won't play out for 100 of 1,000,000,000 of years from now, but that's still pretty uncomfortable. Isn't the universe supposed to last longer than that?

You know, they say that human timescales are nothing compared to cosmic timescales. You know, we've only been around as a species for a blink of an eye, etcetera, etcetera, but life itself has been around for a few 1000000000 years, which is not as long as the whole entire universe, but it's up there. Our universe has been around for nearly 140000000 years. Life on earth has been around for what, like 4000000000 years. You know, it's in the same ballpark.

It's it's in the same weight classes in the same league, and to me, personally, if the universe exists for anything less than a trillion years, like, that's troubling to me. That means this is it. The time scales that our universe has already experienced, you know, the the evolution of life have already experienced. So basically it is it's basically over. That's a surprisingly to me, short amount of time for the universe to exist.

What might, and I'm going to emphasize might, might save us from this utter destruction is Patreon. Same as last episode. Same thing today. Contribute to Patreon and that will prevent the big rip of the universe due to phantom energy. That's patreon.com/pmsutter.

And this is your last chance to get an autograph copy of my book, Rescuing Science, Restoring Trust in an Age of Doubt. Go to Patreon and contribute at the $25 a month level and up even if it's just for 1 month by the end of March, and I will get you an autograph copy delivered directly to your door. Thank you so much. No matter what, whether you get the book or not, whether you contribute a 25 or not, I just appreciate your support. I truly do.

And together, we can avert the total destruction of our universe. What might save us is that so far we've been talking about this phantom energy, this big rip scenario, this w less than minus 1, forgetting that it's just a model. To really understand dark energy, we need to motivate it with a physical theory. We can't just declare the existence of weird fluid that fills up the universe and leave it at that. We need a microscopic description of going on.

We need a quantum theory, some fleshed out physics. You know, we can say, this is an incredible rate of cheese disappearance. You know, only a creature the size of Godzilla is capable of consuming this much cheese. Okay. The the the data may say that, but now you need to motivate it with an actual entity.

You need to pin it on someone, and you can't pin it on Godzilla because Godzilla doesn't exist. This is where the impossibility stuff comes in. The universe seems to be suggesting a big rip scenario, but as far as we know, the big rip is impossible. When we try to replace this model with an actual theory, when we go from a cheese ghost to an actual culprit, when we try to come up with some agent, or ingredient, or entity that drives the big rip, we run into trouble. We usually try to blame dark energy in general, not just this big rip scenario, but any kind of dark energy scenario on a quantum field because quantum field soak up all of space and time already.

Whatever is driving accelerated expansion is is soaking up all of space and time or it appears to be. There are other classes of models where this doesn't happen, but we can talk about that later. And so, we need some sort of entity, some sort of quantum field to drive this big rip scenario. Sometimes it's called the phantom field or the big rip field. I like to call it the big ripper.

It is the thing doing the ripping. It is the thing that's driving this out of control accelerated expansion. We can do that. We do that for basically any dark energy model. But when we try to write down that quantum field and how it would behave and interact with all the other fields and forces and entities in nature, weird stuff comes out.

For example, there's this phenomenon of quark confinement. You know, quarks are the subatomic particles that make up neutrons and protons. It takes so much energy to rip apart 2 quarks from each other. You put so much energy into it that there is enough energy to create new quarks. Given energy by the energy you're putting in to try these tear these quarks apart, and then those new quarks just bind together, and so you can never have a quark alone.

It's not exactly clear how the Big Rip would interact with quark confinement once you get down to that scale. Once it's trying to rip apart a proton, what happens? We don't know. That seems wrong that there'd be other physics of the universe that would prevent this big rip scenario. Phantom fields also have this nasty property of having uncontrolled ground state.

Now ground states, I could get into a whole thing about ground states. This is like the base level of any quantum field. If if you put no energy into a quantum field, you do nothing. You just have an empty box, and it's totally silent sitting in the middle of nowhere. It has an energy associated with it.

We call it vacuum energy. We're used to a certain amount of vacuum energy in our lives. It's actually behind a lot of very cool physics. With phantom fields, they have uncontrolled ground states. They have uncontrolled vacuum energies, which means, they have the capability for big giant particles to just whoosh in and out of existence.

Like, you're just sitting there with an empty box and all of a sudden it's filled with protons, like big stuff and they stay there. That's that's really weird. And in fact, the the ground state, vibrations, the oscillations, the excitations, whatever you wanna call them, can go out of control. It's not just protons. They could, like, manifest an elephant in an empty room and then disappear.

Like, that seems wrong. We don't even need to get microscopic. As in another example, w of less than minus 1 leads to the big ripper field having the curious property of negative kinetic energy. That's like a ball rolling uphill. Negative kinetic energy.

You place a ball a ball at the bottom of a hill and it spontaneously rolls up the hill? That's what negative kinetic energy looks like and that's what a phantom field would look like? That seems impossible. There have been many attempts over the past few years to save phantom energy, to try to make it have the properties it needs for a big rip while still otherwise having, like, a normal insane quantum field, But all of those attempts so far have problems of their own. They they blow up in unexpected places.

They allow for faster than light travel. They don't obey the rules of locality, and so on and so on and so on. Any of the clever attempts we've tried to make a sane phantom field where we still get a big rip scenario, but the quantum field driving it, when we actually try to find a culprit and try to create a viable physical model for this actually behaves according to laws of physics that we understand. We come up short every time. All of this combined gives a picture of a very real possibility of the universe that w is less than minus 1 and a big rip will happen in the future, but this possibility should be impossible.

This shouldn't even be on our radar. According to everything we understand about physics, w of less than minus 1 should simply be outlawed. So at the end of the day, we're stuck. What do we do? I'll say again that all the available evidence is compatible with a no rip universe, just a normal cosmological constant universe, which which has its own mysteries, but they're just slightly less nerve wracking because they appear to be allowed by the laws of physics.

We just don't understand how those physics work. But on the other hand, the Big Rip scenario is definitely not ruled out. We can't say for certain that we don't live in a phantom energy universe. And in fact, the data, year after year after year, tend to prefer a big rip universe over a boring cosalogical constant. The vast majority of theorists will just say, look.

This is stupid. W of less than minus 1 is impossible. It violates everything we know about physics, because the phantom fields make no sense. It breaks this and this and this and this and this and this. I hear that.

I also like to call myself a theorist, but I also know that we need to pay attention to the data. From my entire career as a cosmologist, I've seen plots and figures and measurements of w. I participated in the creation of some of those measurements and plots and figures, and almost every single time I see the data preferring something less than w of minus 1. And every time I see those plots where there's, you know, the the error bars and the uncertainty and say, oh, we're compatible with the cosmological constant. That is the voice of my colleagues, by the way.

And so everything's fine, but I see that little preference, and I can't help but get this wry little smile. I know it's probably nothing that our universe is probably boring. Remember Sutter's law, if it's interesting, is probably wrong. I know that the idea of a big rip of a phantom energy universe is probably wrong. I know that, but still I like to daydream, and I won't let you hold my daydreams against me.

And so I wonder, occasionally, if the universe is telling us that it's doing something that should be impossible, that if the universe is telling us that, if we keep seeing it again and again and again, we say, no. It's impossible. No. It's impossible. No.

The measurements will come down. No. It will change. Don't worry. We'll rule out w, but it just hasn't happened in 2 decades, and it keeps not happening.

Maybe we should be prepared to change the possible. I'm reminded of that Sherlock Holmes quote. You know, when you have eliminated the impossible, whatever remains, however, improbable must be the truth. That's the quote from Sherlock Holmes. But in the case of phantom energy in a big rip universe, like, I get it.

There is no physically viable mechanism for phantom energy. It does seem to break everything we know about physics, and yet the data seem to prefer that scenario. So what if we flipped around that Holmes quote? What if we said, when you have eliminated the improbable, whatever remains, however, impossible must be the truth. Thank you to Lothian 53 on Patreon and Dialogical on email for the questions that led to today's slightly depressing episode.

And also thank you to all my top Patreon contributors. That's patreon.com/ pmsutter. Go check it out. Contribute if you can. I deeply appreciate it every single time.

And last chance to grab a free autograph copy of my book, Rescuing Signs Restoring Trust in an Age of Doubt. My top Patreon contributors this month are Justin g, Chris l, Barbike, Alberto m, Duncan m, Corey d, Nyla, John s, Joshua, Scott m, Rob h, Lewis m, John w, Alexis Gilbert m, Valerie h, Demetrius j, Nathan r, and Mike g. Thank you again everyone. Send me those questions. Ask a spaceman@gmail.com or check out the website, askaspaceman.com.

Keep like, sharing, subscribing, all the usual stuff. Please leave reviews on iTunes. That really helps the show visibility, and I will see you next time for more complete knowledge of time and space.

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