The 5 Great Theories of Physics

Physics can seem pretty complicated, and we’re not going to lie- it definitely can be!

That being said, all that we know about the physical world can be organised into five theories that are all closely related.


Mechanics (sometimes called Newtonian mechanics or classical mechanics) is the theory of the motion of material objects.

It comprises of three main laws:

  1. An object will not change its motion unless a force acts on it.
  2. The force on an object is equal to its mass times its acceleration.
  3. When two objects interact, they apply forces to each other of equal magnitude and opposite direction.


Thermodynamics, of which there are four laws:

  • 0th law – If two thermodynamic systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other.
  • 1st law – Energy can neither be created nor destroyed.
  • 2nd law – The entropy of an isolated system not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium.
  • 3rd law – As temperature approaches absolute zero, the entropy of a system approaches a constant minimum.


Electromagnetism is the theory of electricity, magnetism, and electromagnetic radiation.

All you need to know is what happens when you have + or – charges, what happens when they get close and what happens when they move. That’s it!


Relativity is all about speed.

Special Relativity says that no matter what constant speed you’re travelling at, all the laws of physics are the same.

General Relativity says that being at rest in a gravitational field and accelerating are physically identical.

Quantum mechanics

Quantum mechanics is the part of physics that tells us how subatomic particles work. It also tells us how electromagnetic waves like light work.

Note that this theory is still evolving!

Interested in physics? Come meet the legendary string-theorist, Professor Brian Greene.

Brian Greene Live

Brian Greene is touring across Australia and New Zealand to explore the fascinating story of our universe, and along the way remind us of how unique, fragile and meaningful our circumstances are.

Part philosopher and part physicist, don’t expect him to get bogged down in equations – Brian’s passion spills over into discussions of free will, art, religion and ethics, which he examines through the lens of not only a scientist with 40 years experience, but also as a kid whose curiosity knows no bounds.

This event will be your reminder that the vastness of our universe cares little for human beings, so it’s up to us to take charge of our destiny.

Grab your tickets to see one of our generation’s greatest minds in full force.

The Story of our Universe

The Story of Our Universe: An Introduction to Cosmology is a four-week course covering 13.8 billion years of history.

The universe is old. Really old. If its entire history were crammed into one 24-hour day, the first humans wouldn’t arrive until 23:59!

Together we’ll explore this fascinating history. You’ll learn what the early universe was like, how stars and galaxies formed, and how black holes and dark matter work.

You’ll also learn how this story ends—a big freeze where the universe accelerates into a cold and lonely infinitude of nothingness, a big rip where the fabric of spacetime is torn apart at the seams, or something else entirely.

The course is filled with sublime photographs and vivid explanations which are guaranteed to inspire awe, even in the deepest cynic.

With instruction from one of Australia’s leading cosmologists, as well as a community of like-minded peers, you’ll finish this course with a deeper appreciation of our universe’s grandiosity.

Join us as we venture deep into spacetime.