Is the quantum world really a world of possibilities?

I lost something recently, I searched a lot at home. It was a discount card from a store. 

I remembered that I had a small wallet-like leather card holder where I kept such cards in the compartments, but when I looked, it wasn't there. There was no space in the compartments, so it must have fallen out somewhere.  

I thought about it for a while, I didn't think it was very likely, but I first looked in the pocket of my purse where the old cards were. I examined the cards there one by one, and as I thought, they weren't there.

Then I thought that maybe it had fallen into the pocket of my jacket, but it wasn't there either.

Then I remembered the drawer in the closet, I had a box of old cards in the drawer, I thought I would look there too, but unfortunately I couldn't find them there either.

The lady was watching me from a distance and asked me what I was looking for. 

I said I had a discount card from that store, I lost it for some reason, I was looking for it.

She laughed and said I had it. I took it with me when I had some business there recently, she added.

But I said, there is no space in my card holder, that's why I was looking here. 

I put one of the cards I had, he said, and the section in his wallet where he kept his cards was also full, so he took out a card that he didn't need at that moment and put it in my card holder to free up a space.

Actually, with this story I told you a little bit about the quantum world. 

In the quantum world, probabilities are emphasized in the calculations made for those tiny particles. 

The famous Schrodinger's thought experiment, where a cat is dead and alive at the same time, is actually a probability. It is just another way of expressing probability. 

Maybe it attracts more attention when you put it that way. Both dead and alive! An interesting way of expressing it!

Notice that I didn't look for the lost card under the bed or in the bathroom among the shampoos. 

I looked in the places where it was most likely to be. After a while, I could have thought of the possibility that my wife might have it and I could have asked her about it, but I prioritized looking in the places where it was most likely to be.

The quantum world is like that. Since we can't observe particles directly, we write probability equations for the places where they are likely to be, and we do some calculations with these probability equations.

So actually the cat is not both dead and alive, the probability of it being dead is 50% and the probability of it being alive is also 50%. So actually the cat is either alive or dead, not both, but since this is a form of expression, we say that the cat can be both dead and alive before we open the box and look at it.

I think that's enough explanation for those who are interested.

While we're on this topic, let me also give an explanation of quantum entanglement, which is a very famous topic these days.

You know, socks or gloves are sold in pairs, so are shoes. There are many other things in pairs in this way.

Let's say I send you a pair of gloves, either the right one or the left one, that is, a single one, as a gift, nicely wrapped in a box.

Can you know which glove is in the box before you even open the box? I think unless you have supernatural powers, your answer will be no. This is not about mediumship, so I consider this possibility to be irrelevant.

But would the glove in the box change on the way? The answer to this question must be no. Our courier is a reliable courier! And why would he change what's inside the box?

If I have made this distinction by looking, it means that I know which pair of gloves I am sending you from the beginning, but what if I close my eyes, put each part of the pair of gloves in a box, close the boxes without looking, send one to you and keep the other with me at home? 

In this case, there is no way for anyone to know which part of the glove is in each box until one of the boxes is opened. 

But there is one piece of information we do know. The glove is a pair, either the right glove or the left glove is in any of the boxes. This distinction was made from the very beginning. 

As soon as we open any of the boxes, no matter how far away the other box is, we instantly realize which glove pair is in that box.

This is called quantum entanglement. How simple is that?

Some subatomic particles have a property called spin, the property of spinning around themselves, like spinning tops. 

In particles that start out in pairs, this property is just like the pair of gloves, spinning in two opposite directions.

When you look at any property of a particle in the world of such small particles, you have to interact with the particle. And this causes changes in the particle. 

It's like if we throw a huge boulder at a car to measure its speed and calculate the speed of the car based on the speed of the boulder bouncing off the car. I'm talking about something like this. When we throw a rock at a car, we either reduce the speed of the car, or we cause an accident, or at least we crush it, that is, we damage it. This is how measurements are made in the quantum world.

In the normal world, the photons that hit the car don't damage the car, we can measure the speed of the car from the photons that hit and return, that is light, and we can understand other details we are curious about. We can even take a direct picture of it. Even with our eyes, we can see it instantly. 

But the quantum world is not like that, even a photon is like a rock for subatomic particles.

So in order to understand a property of a particle, you either send a photon at it and observe that property by looking at the reflected photon, but in this case the photon will have an effect on the particle and change its position or energy level, or the particle will directly hit the observation sensor and leave information about that property, but in this case you will still have an effect on the particle.

Current experiments are paving the way for further observations of particles in the quantum world by studying one property in one particle and another property in another particle connected by entanglement from the beginning. 

But don't think that there are great hopes in this regard, after all, like a glove, the only property in two different positions is the direction of rotation, which is not present in all particles. 

So it's actually not that complicated. It's just that, as in Schrodinger's cat, the state of entangled particles before the observation is not yet known, so scientists prefer to say that the particles rotate to the right and to the left at the same time. However, the state of each particle has a 50% probability of turning to the right or vice versa. So again, some possible calculations are made using probability formulas. 

Today, as usual, it seems that when we wake up we will be both happy and unhappy. But I wish that your chances of being happy today are more than 50%.

Love and regards to everyone from Moscow.