Sabine
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What is "Nothing"?
🕑 Added 2022-09-24 12:00:05 +0000 UTCLike most videos on YouTube, this is a video about nothing. But we’re a science channel, so we’ll talk about nine levels of nothing. What are the nine levels of nothing? Can you really make a universe from them? And if someone asks you why there is something rather than nothing, what’s a good answer? That’s what we will talk about today.
First things first, what do we mean by “nothing”? A first attempt to define nothing is to look at how we use the word in everyday language. Suppose your birthday is coming up and you say “Oh, I want nothing.” So when I give you a box for your birthday, you expect it to be empty It’s nothing, in the sense that it doesn’t contain any objects. We will call this the level 1 nothing. It’s a pre-science nothing, the nothing you might refer to before you’ve ever heard of physics.
But of course, you have heard of physics, and so you know that even a box full of level one nothing still contains air, and air is made of something. You wanted nothing for your birthday, and certainly you’ll be disappointed to get air instead. Let’s therefore pump all the air out of this box. We’ll call what’s left the level 2 nothing. It’s what was called a vacuum in the 17thcentury, no objects, and no air either.
Okay you might say, but we don’t live in the 17th century, and when you said you want nothing for your birthday you really meant it. If we just pump out the air, there’s still the occasional cosmic ray inside, or neutrinos, or dark matter particles, if they exist. So, we go one step further and remove all types of matter, this gives us the level 3 nothing. Indeed, since objects and air are made of particles, removing particles includes the previous two nothings.
But even if the box is closed, there would still be radiation in the box, for example in the infrared, which is maybe not much, but it’s something. And the magnetic field of the earth would also still go through the box. Therefore, we now also remove all types of radiation and all fields. Because you wanted nothing for your birthday and of course I want you to be happy. Now we have a level four nothing: no particles, no radiation, no fields. What you have left then is what you could call the 21stcentury vacuum.
The level 4 nothing is however is still something. For one thing, many physicists argue that the vacuum has an energy density and pressure and associate this with the cosmological constant. As I explained in this earlier video, I think this doesn’t make sense, the cosmological constant is just a constant of nature which determines the curvature of empty space. Empty space just isn’t necessarily flat. Talking about the curvature of empty space as if it was energy density and pressure is just a weird interpretation of geometry.
Even leaving aside the cosmological constant, the 21st century vacuum isn’t nothing because in quantum field theories, like the standard model of particle physics, the vacuum contains virtual particles that are created in pairs but quickly destroy each other again. They come out of the vacuum and disappear back into it. Virtual particle pairs are like couples you’ve never heard of that pop up in your news feed, destroy each other, and disappear back into nothing. Except with maths.
We can’t directly measure virtual particles, that’s why they’re called virtual. But we can infer their presence because we can measure their influence on other particles. Or we could, if we hadn’t removed those from the box already.
For example, if we look at the energy levels of electrons around an atomic nucleus, these are slightly shifted in the presence of virtual particles. This can be measured, and it has been measured. That’s one way we know virtual particles exist.
You could argue that the phrase “virtual particle” is really just a name for a mathematical expression that we use to calculate measurement outcomes, and I would agree. But be that as it may, we can observe their effects and nothing has no effects so it’s got to be something. And you wanted nothing for your birthday, not a box full of virtual particles. Besides, virtual particles can sometimes become real, for example near black holes, so they can actually kick us back from level four to level three.
To get to level 5 nothing we therefore remove the twenty-first century vacuum too. Now we have neither virtual nor real particles nor radiation nor fields and there’s also no way that any of them can reappear from the vacuum. What’s left in the box now? Well. There’s still space and time in it. And time is money, and money is the root of all evil, and that’s a terrible joke, but still something rather than nothing.
This is why for level 6 of nothing, things get decidedly weird because we remove space and time, too. And just to make sure, we will also remove all other equations and laws of nature that might give rise to space and time, such as strings or quantum gravity, or whatever other idea you believe in. Remove all of it. At this point there is nothing left from our theories of physics.
So why is there any physics at all? This question is one of the reasons we’ll never have a theory of everything, because even the best theory can’t explain its own existence. Scientific explanations end at this level, and it’s probably where this video should end, but I admit I enjoy talking about nothing, so let’s see what else there is to say.
I have taken inspiration for this video from an essay by Robert Lawrence Kuhn, to which I will leave a link in the info below. He also talks about it in this video. My first six levels of nothing are similar to his, though not exactly the same because I’ve looked at it from the perspective of a physicist. But Kuhn doesn’t stop there, he has three more levels of nothing.
Taking away everything physical still leaves us with something in your birthday box because you might grant the existence of non-physical entities. For example, some people believe in god, or other religious ideas, like the belief that consciousness is non-physical. In level 7 we remove those, too. Theological explanations end at this level. If you think that god necessarily has to exist then you have to get off the bus at level 7 and accept that the question why god exists doesn’t have an answer.
Is the box finally empty? Not quite. There’s still mathematics that could be said to exist in some sense. That is, we have abstract ideas and objects, numbers, sets, logic, truths and falsehoods, and the entire platonic world of ideals. For the 8th level of nothing, we remove those too.
Has this finally removed everything? Are you finally happy with your birthday gift? Well, there’s still the possibility that something comes into existence even if that something doesn’t exist. And a possibility is something in and by itself. So, for level 9, we also remove all possibilities. This is Kuhn’s final level of nothing. It’s the best nothing I can give you for your birthday. I hope you’re happy now.
The ninth level of nothing leaves us with the always interesting question whether the absence of something is also something, which is why philosophers like to discuss whether holes in cheese exist. Personally, I’m more interested in the cheese. I guess that’s why I’m a physicist and not a philosopher, but I found Kuhn’s classification of nothings useful because it explains why we sometimes talk past each other apropos of nothing.
For example, “inflation” is a currently popular theory in physics according to which our universe was created by a quantum fluctuation from a vacuum. We have no evidence that this is correct, but let us leave this aside for today, and just ask what kind of creation this would be if it was correct. The idea of inflation is that you have a big space that’s filled with a quantum vacuum, and every once in a while a quantum fluctuation succeeds in becoming so large that it begins to grow. Indeed, it grows into an entire universe like ours, with cheese, and holes in it, and all.
In such a vacuum there are many fluctuations, and therefore the creation of a universe doesn’t happen only once, it happens over and over again. It’s a type of multiverse called “eternal inflation”. We just talked about this some weeks ago. The beginning of our universe in this eternal inflation would be a creation from a level four nothing.
Physics can get you a little further than this because you can write down a theory in which space and time is created from a state without space and time. It’s arguably somewhat hard to imagine what this means, but you can certainly write down mathematics for it.
You see, I just define a symbol for a state without space and time, and an operator that creates space and time, then I let the operator act on the state, and voila, I’ve created space and time. Ok, I have oversimplified this a little, but basically this is how it works. I really think people are way too respectful of all the stuff that physicists made up and get away with just because their maths is incomprehensible.
Lawrence Krauss’ book “A Universe from Nothing” is about this idea of creating space and time from nothing. And this would be a creation from a level 5 nothing. But even if you don’t believe in God, a level 5 nothing is still something. To begin with it has the mathematics that give rise to all the rest.
If physics doesn’t answer the question why there is something rather than nothing, then what could? Philosophers have discussed that back and forth. I’m not much of a philosopher and have a nothing worthwhile to add. That’s a ninth level nothing. But just in case someone stops you on the street and asks “why is there something rather than nothing”, let me tell you the three most popular answers that I have come across.
The most popular answer at the moment seems to be that nothing is absurd. It doesn’t make sense in and by itself and can’t be. It’s just a confusion of human language that we have inflicted on ourselves. The difficulty becomes apparent if you try to explain what nothing is, because any statement about it requires something. I mean if I can talk about nothing, then nothing it’s the thing that I talk about and it's therefore something?
Another answer is that no explanation is needed, or there is no explanation. God made it, que sera, sera, please move on, nothing to see here. See what I did there?
A third answer might be that our universe, or at least any universe, is in some sense the best option, and nothing doesn’t live up to the requirement because nothing can’t be any good.
If someone asked me on the street why there is something rather than nothing, I’d probably just shrug. I can’t think of any way to answer the question, and I also don’t see what difference it would make if we could answer it. I mean, suppose someone came tomorrow with a 2000 page proof that something must exist, what would it be good for? I guess I could do a video about it.
More seriously, just because it’s not a question that I want to spend my time on doesn’t mean I think no one should. In fact, I am glad that we are not all interested in the same questions and I’m happy to leave this one to philosophers. Do you have an answer that I didn’t mention? Let me know in the comments.
Comments
I've thought of time being fluctuations in a medium such that its density manifests as gravity. Cycles vibrate in this field, giving rise to the human perception of time. The further out an observer is from a gravity field, the less time cycles, or goes slow. So it makes you wonder, what would time be like on a massive planet like Jupiter? Will it vibrate much faster than on Earth or much the same?
Greggery Peccary
In answer to the question why is there something rather than nothing, a good empiricist would just reply, How can you tell the difference? "... the always interesting question whether the absence of something is also something." I believe Plato has been dinged for his resolution of this issue. There is the different ontology of the Stoics which claims that reality contains more than what exists, i.e. the root genus "something" contains existing (material) things and non-existing (non-material) things. Some have even said for the Stoics there is a third 'neither material nor non-material' subgenus of things for stuff like fictional beings (or things in the past) and limits. Maybe that's the kind of thing that is impossible to remove from the gift box. After all if you remove nothing from the box, nothing would still be in the box.
I think that I didn't say anything about teleportation. But there are not only photons moving at c. Elementary particles have internals which oscillate permanently at c, a phenomenon which Erwin Schrödinger has called: "zitterbewegung". This oscillation is BTW the physical cause of relativistic dilation. At least I do not know any different cause of dilation.
I can only imagine photons as bouncing/wriggling around through a volume of space-time within the box, not teleporting instantaneously or something else.
Why / in which way?
You've stumped me. 🙂
Right, but the case which I have described is different. The fundamental case of “time”, the being of ‘earlier’ and ‘later’, makes only sense if both events happen at the same position. If we look at the case of two events at two different positions in the box, we have to look at the case of linear time, and that means the use of oscillators – here called ‘clocks’. And these oscillators have a period that depends on their motion. And in turn the dependence on the motion has to do with the constancy of the speed of light c. Now the question regarding the box: If c is constant in the box, is this the property of something general being in the box or is it only the intrinsic property of an object having this speed c? This at the end is the question of the origin of relativity.
All of the box isn't reachable at once, travel still needs to occur between any 2 or more points on, inside or along the edges of the box and this isn't simultaneous, is the thought that came to me.
Sabine, you say: “What’s left in the box now? Well. There’s still space and time in it.” My question: How can be “time” in it? Which means: what is time - is it more than a pure abstraction? If there are two events somewhere then the one must be earlier and the other one later. That is the fundamental case of “time”. Now - has something to be in the box so that this is true? Is a situation thinkable where this is not possible? The other – the linear – case of time is the abstraction of the action of oscillators. This needs the presence of an oscillator (at least principally); so it does not matter for this question. We could raise similar thoughts about space. But not now on this evening.
D Brown
You beat me to it.
Nothing is impossible, the old philosophers said. And look, modern physics says the same.
"The reason that there is Something rather than Nothing is that Nothing is unstable." -- Frank Wilczek, Nobel Laureate, phyiscs 2004 Nothing is an awe-inspiring yet essentially undigested concept, highly esteemed by writers of a mystical or existentialist tendency, but by most others regarded with anxiety, nausea, or panic. --- The Encyclopedia of Philosophy "What is there? Everything! So what isn't there? Nothing!" --- Norm Levitt, after Quine
Definition of nothing: Nothing is more pleasant than reading a new Sabine Hossenfelder column with a nice cup of coffee on a Saturday morning. /fanboi
I think that the maths-level nothing should occur earlier in the deal since it's a sort of quasi-field information thingy. Maybe?
Rad Antonov
https://www.youtube.com/watch?v=0BvFszgQ-CA&feature=share&utm_source=EJGixIgBCJiu2KjB4oSJEQ
Terry Bollinger
The worst scientific prediction in history is quantum field theory’s claim that the vacuum has so much energy that the universe should instantly collapse or explode. The source of this failure is assuming that the “nothing” between interacting particles is identical to the “nothing” of special relativity. They are, in fact, irreconcilably different versions of “nothing.” The solution to the vacuum density problem is to admit the mismatch and return to Einstein’s original special relativity concept of the vacuum as independent of any frame. Quantum field theory is possibly the most precise and predictive theory set ever devised, yet its very success obscures a critical point: It is an ether theory in the sense that the context of its particles, energized fields, and endpoints always bind its results to a well-defined and entirely classical inertial frame. Whether used to calculate the Lamb shift in a hydrogen atom or the path of a photon in a Feynman diagram, every quantum field theory calculation begins and ends with the assumption that classical entities exist with well-defined locations in space and time — in other words, a well-defined inertial frame. These inertial frame boundaries make all variants of quantum field theory into ether theories, that is, theories for which a specific inertial frame dominates over all others. Einstein’s 1905 papers on special relativity did not do this. Einstein, at least in 1905, was so excruciatingly careful not to make frame-dependent, ether-like statements about the vacuum that he refused to define even the speed of light as having meaning except in the context of a single observer in a well-defined inertial frame — and even then only as the average of light going out and then returning to that observer. In his must-read book The Structure of Scientific Revolutions, the late and truly great science philosopher Thomas Samuel Kuhn defined two types of science. In normal science, extraordinary past successes generate deep confidence that, despite anomalies here and there, the current framework must inevitably resolve those anomalies, even if those resolutions prove extraordinarily difficult to uncover. In revolutionary science, those anomalies provoke a crisis in which a new generation of thinkers loses confidence in the old model and begins examining deeply held and seemingly “obvious” assumptions that underlie that model. The vacuum density problem is just such an anomaly. What is remarkable is that the simple assumptions that generated this anomaly have gone unchallenged for so long. ---------- Terry Bollinger CC BY 4.0 2022-09-24.08:35 EDT Sat [Updated 2022-09-25.16:45 EDT Sun, tweaked Mon] PDF: https://sarxiv.org/apa.2022-09-24.0835.pdf
Oh my goodness. I was just thinking of the concept of nothing on Wednesday! I have not read/watched yet. So here is what I thought of before I absorb your information: If you consider that all everything is just wave forms in multiple dimensions (perhaps many more than we currently figure), then perhaps there are maths that make our existence, and many other existences that are not ours because the maths don't overlap. In fact, an infinite number of them. All mathematical possibilities. If you overlay all of them, the chaos grows until you end up with every space saturated with data points. You end up with a homogenous singluar value. On an unfixed graph, this could be any value, say all 1. Or it could represent 0 as well. With no abstraction, they look identical. So 0 is 1. And one, when divided infinitely, creates the multi-verse. Okay, now off to watch your show!
