Physics is a tough subject, and many students will attend physics tuition to better acquaint themselves with its many laws and equations. Within physics, there are a few topics that are tougher than others. Opinions differ as to which ones are the toughest, however, it is generally accepted that most students face difficulty with topics that involve a lot of complex mathematical calculations. It is arguable that the top 3 topics that students struggle with are thermodynamics, quantum mechanics and string theory.

Let’s find out why they are so hard.

**Thermodynamics**

Thermodynamics studies the relationship of heat with other forms of energy. Well, it sounds easy, doesn’t it? The first law says that energy cannot be created or destroyed. So far so good. But a lot of students don’t grasp its difficulty until they come to the second law of thermodynamics, which can be expressed in several different ways according to its context.

One way this law is often expressed is that the total entropy of an isolated system cannot decrease over time. What it means is that the total energy of a system from which neither energy nor matter can escape or enter remains constant. But what it actually means is that in the real world, total entropy of a system always increases over time and that the process is irreversible.

Perhaps the simplest way to express this law is that heat transfer always occurs from a hot body to a cold body. But after that comes the calculations (entropy, thermal efficiency, combustion, etc.) and that’s where many a student find themselves scratching their head. You need to be very good at calculus and differential equations to perform the necessary calculations.

**Quantum mechanics**

Quantum mechanics is the study of the behaviour of electrons, photons and other particles at the smallest scales of energy level, called a quantum. A quantum is defined as a discrete quantity of energy whose magnitude is proportional to its frequency of radiation. At this level, particles behave in a very whacky and unpredictable manner.

For many students, the very concept of quantum physics is difficult to grasp. The prominent physicist Niels Bohr is reported to have said that anyone who does not admit to being shocked by quantum theory has not understood it.

Once you get past that, there are the calculations which require a high degree of knowledge of calculus and differential equations. Anyone who is not good at these will soon find himself or herself lost. This is why quantum mechanics ranks at the top of the list of difficult physics topics.

**String theory**

String theory is the idea that everything in the universe is made of infinitesimally small one-dimensional objects called strings. According to this theory, an electron, which is considered as the smallest particle (with no internal structure), is made of strings. Viewed from larger scales, strings look like ordinary particles whose properties, such as mass and charge, are determined by the string’s vibration.

The reason students find string theory so difficult is it that it is almost entirely mathematical. One has to be really, really good at calculus and differential equations to understand string theory. If you are struggling with any topic, even those not mentioned in this article, consider joining a physics tuition class.