Does The Universe Exist When We Aren’t Looking?
Quantum Physics requires an observer to have a definite outcome, so does that mean our Universe requires an observer to exist?
We have all heard of Schrodinger's Cat; the cat is both dead and alive (known as a superposition) before opening the box and fixing its state, hopefully with the cat being alive. But how we interpret this weird quirk of nature can have some very far-reaching implications. Like the Universe not really existing if we aren’t looking or astronomers killing aliens. Welcome to the mind-bending world of Quantum Interpretations!
First of all, a super quick recap on what Quantum Physics actually is.
Quantum Physics is essentially a set of equations that predict how tiny stuff works with amazing accuracy. These equations show that particles don’t exist as fixed point-like particles. Instead, they exist as an amalgamation of all possible outcomes until observed when they fix their outcome. This amalgamation of outcomes are known as superpositions.
Plenty of experiments show the effects of Quantum Physics, but the most famous is a thought experiment by Ewin Shrodinger that explains how things can exist in superpositions.
So, a super quick recap of Schrodinger's Cat to explain superpositions. The cat is placed in a box with a vile of poison. The poison has a release mechanism that uses an unstable atom of caesium, once the atom decays the poison is released. Then the lid is closed so that the cat and caesium atom can’t be observed. The caesium atom is now in a superposition of being decayed and intact because there is no possible way to predict exactly when it will decay (also known as a Quantum Event). But because the cat will die once it decays, the Cat is also in a superposition of being both dead and alive.
So the equations predict the behaviour of tiny particles and Schrodinger's Cat is a nice way to visualise it (unless you are the metaphorical cat!). But these don’t explain what actually happens when something isn’t being observed, they only predict what the outcome could be. This is what Quantum Interpretations try to do by explaining what is actually happening behind the scenes of Quantum Physics, or to put in another way, what is happening to the cat in the box?
There are two main Quantum Interpretations with variants of each. The most popularly taught one is the Copenhagen Interpretation. This states that the cat truly exists in a superposition of being dead and alive, things become ‘fuzzy’ when not observed. Weirdly, this is the most simple interpretation, but it has some far-reaching effects if true!
It is tough to get your head around what the Copenhagen Interpretation means for the nature of reality. I know, it took me ages! So let me explain it a little more.
The Copenhagen Interpretation says that when something isn’t being observed, whether it is a particle or a cat in a box with some poison, it stops being rigidly defined and becomes this fuzzy blob of superposition. Except, not just a superposition of dead or alive, but of all the possibilities that could happen. This means that unobserved things, whether tiny particles or cats exist a hazy cloud of all possible outcomes since they were last observed.
This is the most simple interpretation of Quantum Physics. It doesn’t require any add-ons or an infinite number of Universes to let the maths work out (like the other interpretation known as the Many-Worlds Interpretation). But there is an issue with the Copenhagen Interpretation; it really messes with reality. Let me take you through a few examples to show you.
Does the Universe need life to exist?
In a word, yes, it does exist. But everything is undefined and ‘fuzzy’. The whole Universe exists as a huge pile of interacting superpositions. But does an undefined Universe of interacting possibilities really exist? If something isn’t fully defined, I'm not convinced it truly ‘exists’ as we understand existence.
This then means that for the Universe to exist truly, it needs life to observe it. So, in a way us observing the universe creates it, you made the Universe this morning by waking up.
So in a nutshell, does the Universe exist when we aren’t looking? According to the Copenhagen Interpretation, no, it doesn’t. If you aren’t looking at it, it's a weird hazy cloud of superpositions waiting for you to look at it.
This may make you want to stare out of the window to keep reality solid and determined rather than this mess of possibilities. This is not advised; people will think you have gone mad.
You may find that this is the answer to the article and we can wrap up here. But oh no, there is more because this weird world means that some of the things we do actually affect the world around us…
Are Astronomers killing Aliens?
If astronomers had never peered out into space, would the Star Systems near us be in a superposition of hosting alien life and not?
Possibly… It’s complicated. As always with Quantum physics.
We can think of these Star Systems like the cat in the box, both dead and alive but with an added layer of complexity. They are in a superposition of being dead, alive with simple life, and alive with complex life.
Organisations like SETI have been looking for advanced aliens for years and found nothing concrete. I don’t want to go into too much detail about how they do this on this article, but needless to say that they have solidified that aspect of the superposition with a hard no. So, our nearby planets are now in a superposition of dead or alive with simple life.
We don’t know what the chances are of simple life existing on exoplanets. If we find life in our Solar System, like in the Martian lakes or Europa’s oceans, it could mean that life is common in the Universe. So these exoplanets may host microbial mats or hydrothermal bacteria.
You may think from all these light-years away we can’t observe these tiny communities. But you’d be wrong. Astronomers can now see the composition of an exoplanet's atmosphere by observing it’s transitions past its Star. If an exoplanet has life on it, they will likely have a large effect on the atmosphere (like oxygen and organic compounds) that we can pick up from these huge distances. As astronomers start rolling out this amazing technology, they are solidifying the fate of these exoplanets. However, they aren’t finding any life.
Just as if Shrodinger opened the box to find the cat is dead, our Astronomers might be sterilising the Star Systems around us by simply looking.
Did we kill the Universe in 1998?
In 1998 astronomers discovered Dark Energy, an ‘anti-gravity’ that appears to be pushing the Universe to expand at an accelerating rate. This means that in trillions of years, the expansion of the Universe will be faster than the speed-of-light and the Universe will effectively end. But did it have to be that way?
Before discovering Dark Energy, we didn’t know how the Universe would play out because we didn’t know how dense the Universe is. We thought that if the Universe was too densely packed, gravity would win and everything could come back together as the ‘Big Crunch’. Or, if it is too light, then the Universe would keep expanding from the Big Bang's momentum at a slowing rate as the ‘Big Yawn’. Or if we were fortunate, the two forces would balance out, and we would live in a perfectly balanced Universe that doesn’t expand or contract once it has reached a certain size, known as a ‘Static Universe’.
It is possible that before 1998 the Universe existed in a superposition of Big Crunch, Big Yawn, Static Universe and Dark Energy. The Universe could have lasted forever! But we went ahead and observed it. So we fixed ourselves as the Dark Energy Universe.
So did astronomers kill the Univers in 1998? If the Copenhagen Interpretation is correct, they did!
Is this really the nature of reality?
You may have just read all of this and thought ‘this sounds like utter crap, reality isn’t a wishy-washy soup of possibilities’ and many scientists would agree with you because this doesn’t seem to make sense. So scientist came up with two ideas that solve this weirdness. It all depends on sizes and how many Universes there are… Let me explain.
The first idea is that the Copenhagen Interpretation is correct, but superposition doesn’t scale up past an atom's size. The idea is that these possibilities cancel each other out as you pile more and more particles (and therefore superpositions) together. So while at the atomic level, our Universe is still a wishy-washy soup of possibilities, if you zoom out to our scale things become certain, set and rigidly defined.
This makes sense to how we feel the Universe works and means all these weird possibilities of killing aliens and such don’t happen. But there is a problem. There is nothing in the Copenhagen Interpretation to suggest that this cancelling out actually happens; it is just a theory with very little evidence (so far).
The second idea is a completely different interpretation known as the Many-Worlds interpretation. It basically states that superposition doesn’t truly exist. Instead, there are infinite Universes, which means there are infinite identical Universes to this one, that all branch-off when we observe and fix these possibilities.
It is as mad and as complicated as it sounds!
So this interpretation basically states that in the box there are an infinite number of dead and alive cats, and when you open the box, you fix which branch of Universes you are in. This doesn’t really solve the problem as infinite Universes are even harder to get your head around than large scale superpositions!
So, we end up coming back to the Copenhagen Interpretation without the superpositions cancelling each other out. This means that superposition's quantum effects have to work on the atomic level and the macroscopic level (our size). Large-scale quantum effects aren’t unheard of, but the idea that this effect can scale up to the size of the Universe would push quantum physics into new territory. But as this theory is the most simple explanation, it appears to be true.
So, does the Universe exists when we aren’t looking? Well, it is a hotly debated topic for Quantum Physicians.
It depends on which camp you place your flag. If you think that superposition can scale up then, yes. The Universe outside of your observational bubble is a weird undefined mess, hardly what you would call proper existence. But if you think the Quantum Physics should stay small and cancel out as things get big then no, the Universe is exactly as it was when you look away. Maybe one day we will be able to test and prove which is the correct nature of reality, but until then, I love the weirdness of the Copenhagen Interpretation. It’s far more exciting to picture a mysterious Universe of unset possibilities.