Superposition Principle, Measurement Problem and a cat

In my last post, I mentioned something like this:

"In a quantum world, put a cat and a bomb with a 50/50 chance of blowing up in a bunker. Before we open the bunker, the cat is not dead nor alive, but it's both dead-alive at the same time... until we open it."

Since then, I have been researching more about these little pieces of quantum mechanics that makes it so interesting. So to begin, I like to introduce you guys to a cat, more specifically Schrödinger's cat. 

The Schrödinger's cat is a thought experiment, came up by Erwin Schrödinger. In the original version of his experiment, he proposed to use a hammer that is linked to a sealed box of radioactive substances; if the sensor detects some radioactivity(substances decaying), the hammer will set off and break a flask of hydrocyanic acid, thus killing the cat. However if it doesn't decay, the cat lives. Before the box is opened, the cat is in a superposition state, both dead and alive. How in the world does this work, which you might ask by now.

Let's step back and look at Quantum Mechanics in the big picture. It is a part of physics that explains how very small things work, which are things like: electrons, photons etc. Why is there a whole branch of physics dedicated to these particles? Because they act very differently from our normal everyday things. Two basic rules of Quantum Mechanics that you must first understand is the Superposition Principle and Measurement Problem. The Superposition Principle claims that an object can be in all possible states at once. To put that in perspective, let's say there are three possible place for that object to be in: on the table, under the table, in the drawer; using the normal day logic, it can only be at one place right? But in the world of quantum mechanics, the object is in all three places at once. The Measurement Problem comes in when that object which was in a superposition state, is being observed. So basically, the object was initially at all three places(on the table, under the table, in the drawer) at once, only until the object is being looked at. Let say you did looked at the object. It will lose it's superposition state in an instant and appear under the table. In Quantum Mechanics terms, the superposition state will immediately collapse once it's state is measured.

Okay, since we have already go through the basic rules, now let's revisit the Schrödinger's cat. So the life and death of the cat is ultimately decided by the radioactive substance(if it decays or not). The radioactive substance, due to being in a box and not being observed, is stuck in a superposition state. Hence causing the cat too be in a superposition state, both dead and live at the same time. Once the box is opened, the superposition state immediately stops and chooses an outcome. You will either see a live cat or a dead cat when you open the box.

The two basics rules of Quantum Mechanics not only explains how Erwin tortures cats. Remember the chemistry textbooks that taught us that atoms looked like this(Fig.1a)? Something like a nuclei with orbiting electrons like how the moon orbits the Earth. In truth it actually looks more like this(Fig. 1b). The black part being a cloud of probability, which is basically a superposition state of the electrons thus it could be anywhere within the cloud. When you try to measure where the electron really is at, it immediately chooses where it's at, this is linked back towards the other statement I posted in the first blog: 

"The more you know about how fast something is, the less you know about where it is; and the more you know where something is, the less you know about how fast it is."

Fig. 1a

Fig. 1b

I hope this post is able to help you understand the basics of Quantum Mechanics. I will be looking more into Quantum Mechanics and also how we are able to use this to our advantage. Quantum Mechanics is truly amazing; as Niels Bohr, a Danish physicist, had once said: 

"Those who are not shocked when they first come across quantum mechanics cannot possibly have understood it." 

Thank you.

Sources:

• ·         http://cdn.arstechnica.net/wp-content/uploads/2013/11/atom.jpg
• ·         http://www.uh.edu/engines/heliumatom.jpg
• ·         https://en.wikipedia.org/wiki/Measurement_problem
• ·         http://whatis.techtarget.com/definition/superposition
• ·         https://www.youtube.com/watch?v=b_ddt6J1Bio