This is a very difficult question.

Someone else asked “What is time?” and I think this might be one of the hardest concepts to understand, because everything we say and think is bound up with the way we experience time as a series of events some of which have already happened and are known or knowable, and some of which haven’t and are unknown or unknowable. If time isn’t really like this, it will be hard to understand.

Physics has some great methods to understand difficult concepts which build on algebra. By
representing quantities and ideas as mathematical symbols which can be moved about and rearranged, it is to develop new ideas which can’t easily be expressed in words (or thoughts?). If you get a degree in Physics or Maths, these skills are in great demand, because you can solve some problems this way when mere mortals (like me) can only scratch our heads. Drawing and imagining diagrams can also be helpful.

Writing computer programs that specify exactly how you think things work can often be helpful. If there are any gaps in your thinking your program doesn’t work. By fixing the program, you get a much clearer idea of what is going on. You can also try out all sorts of experiments with the program, and then try them in real life to see if the model is accurate. I did this for my PhD on how people learn new words.

If I am trying to understand something very difficult, I sometimes make a list of all the different ways it might work (including “none of the above” at the bottom of the list). Then I try to figure out how I could distinguish the different ways it might work, e.g., by trying an experiment.

Another way to understand how something works is by analogy with something else (often very different) which you do understand.

Difficult to think of a tougher question than that, Isabella – well done!

I think we have to name physics the winner when it comes to mind-bendingly hard concepts.

All the ideas of quantum mechanics and the weird things that happen on the atomic and sub-atomic scale (like the strange motions of electrons around atomic nuclei) are very unfamiliar to us since they are so far removed from our everyday experience. That makes them very hard to understand and probably explains why it took until the 20th Century to come up with the idea.

On this subject I love this quotation about from Richard Feynman – a nobel prize-winning physicist: “I think I can safely say that nobody understands quantum mechanics.”

If that’s his view, what chance do the rest of us have!

Hi Isabella – as a student of particle physics, ‘quantum field theory’ is one of the hardest topics I have studied. Thankfully there are lots of experts around willing to help!

Something to do with conciousness. I am not sure why I think (or know!) I am alive, separate from everyone else and me, and I think thinking about thinking about things is really tricky!