Physique Quantique/
Quantum Physics

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Quantum Lumps

Now that you have completed Quantum Physics 101 (Missed it? Go back to Quantum Physics 101 to help you understand.), you are ready to move on to the next step. Don't worry, you'll understand the next pages regardless of the order in which you read them, just as long as you start with Quantum Physics 101. Have fun!

Table of Contents:


Introduction


What are Quantum Lumps?


Why are They Important?

   Quantum lumps is a concept which is directly linked to many concepts in quantum physics, but also in our everyday lives. 

What are Quantum Lumps?


    Quantum lumps is a term which is used to describe little packets which are a result of a phenomenon we call quantification. Quantification basically states that some qualities of matter aren't continuous, that they are divided into little "packets" or lumps. Physicists say that matter is discrete, which means that it comes in discrete units, or lumps. Max Plank was one of the first physicists to work on this. In fact, he discovered what we now call Plank's constant (see Vocabulary) which is equal to the "size" of one quantum lump, or quanta. Let’s take light for example. (See image right.) When we see light, we see a continuous stream of it. It doesn't look like little lumps, or little drops as if it were rain. We see light as a continuous beam. But at the quantum level, this isn't quite true. In fact, we know that light it made up of photons. These photons sometimes behave like waves and sometimes like particles (for more information, see Wave-Particle Duality), but whether they are acting like particles or waves, they are always discrete. This means that they are like little lumps equal to Plank's constant. These lumps are just so small that we don't see them.

    Photons are emitted by certain atoms when the atom is excited. In an atom, different electrons occupy different energy levels (because they are fermions and respect Pauli's Exclusion Principle, see Vocabulary). When the atom is excited (say, by an electrical current), the electrons jump to a higher energy level (see image, left). The "height" of each level, or the difference in energy that each level has compared to the last (which is smaller and smaller the higher the energy state) is directly linked to Plank's constant. When the atom is no longer excited, the electrons, which prefer lower energy states, jump back down to lower energy states. When they do this, they release the energy (that they "lose" by going from a high energy state to a low energy state) in the form of a photon (or many photons). Each "emission" (which we call photons) is energy equal to Plank's constant. From the time they are emitted (by atoms or other objects or reactions), photons stay quantified. Physicists have managed to extrapolate this quantification to the rest of the quantum world. 

Why are They Important?


 

   In and of itself, the concept of quantum lumps has little influence in the "useful" sense. But, mathematically and theoretically, it has many implications that are difficult to grasp without going into details. The important thing to remember is that quantum lumpiness and the concept of quanta revolutionized our view of how our world is made. It completely changed how we think of the basis of our universe, because it tells us that constance is a concept that we invented, but that it really isn't true. It also explained many things and equations that we didn't quite understand yet when it was discovered (like black body radiation). 

   One very interesting application of quantum lumpiness is a theory that Leonard Susskind (a professor at Stanford University) thought up. It's called "The World as a Hologram". It is quite complex because it is difficult to wrap your mind around it, but it is interesting to think about. There are many articles that have been published on this topic that you can find on Internet and most of all, there are many videos of conferences given by Leonard Susskind that you can find on YouTube if you wish to deepen your knowledge on this topic!