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What is time?

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Time

What is time? Does it have a beginning? Is it possible to travel through time? And what does it mean to say that time is relative? The following Plus articles and podcasts introduce you to the concept of time and to some of the riddles it poses for physicists.

For an introduction, read

  • What is time?, which sheds some light on the idea that time is relative, as well as on one of the biggest questions in physics — why time has a direction. It also explores the intriguing idea that time doesn't exist. A version of this article is also available as a podcast.

For a little more detail, read

  • What's so special about special relativity? which takes a more detailed look at Einstein's special theory of relativity and shows, using some straight-forward calculations, why your perception of time depends on how fast you're moving.
  • What happened before the Big Bang? asks whether the Big Bang really marks the beginning of time, or whether there was something before it. The answers are mind-boggling!
  • The puzzle of time takes a closer look at the "arrow of time" (the question of why it has a direction) with the help of some friendly philosophers of physics and the eminent Roger Penrose. You can also listen to our interview with them in a podcast.
Read more about...
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  • What do chocolate and mayonnaise have in common? It's maths! Find out how in this podcast featuring engineer Valerie Pinfield.

  • Is it possible to write unique music with the limited quantity of notes and chords available? We ask musician Oli Freke!

  • How can maths help to understand the Southern Ocean, a vital component of the Earth's climate system?

  • Was the mathematical modelling projecting the course of the pandemic too pessimistic, or were the projections justified? Matt Keeling tells our colleagues from SBIDER about the COVID models that fed into public policy.

  • PhD student Daniel Kreuter tells us about his work on the BloodCounts! project, which uses maths to make optimal use of the billions of blood tests performed every year around the globe.