Science fiction, science fact: What is time?

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What is time? In the latest online poll of our Science fiction, science fact project you told us that you'd like an answer to this question. So we went to ask the cosmologist and theoretical physicist Paul Davies about the nature of time and revisited the musings of cosmologist John D. Barrow on the beginning of time and the physicist Kip Thorne's take on time travel. We also bring you two timely articles from FQXi who are our partners on this project. Happy reading!

And don't forget to vote for the next question you'd like to have answered!

What is time? — Newton thought that time was absolute. Einstein thought it was relative. Today some people think it doesn't exist at all. Or is it an emergent phenomenon? Paul Davies explores.
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This interview is also available as a podcast.

What happened before the Big Bang? — Did the Big Bang mark the beginning of time? Not if we live in a bubble multiverse, says John D. Barrow.
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This interview is also available as a podcast.

Is time travel allowed? — We're all on a journey towards the future, but can we travel into the past? Find out with Kip Thorne.
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Time and the multiverse — Why does time appear to flow in one direction only? This article from the FQXi community website explores the question, assuming that we live in a bubble multiverse.
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The crystallising Universe — According to Einstein, the past present and future all have the same character. So why do we feel that there's a special moment called "now"? This article from the FQXi community website looks for an answer in quantum mechanics.
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I would say that time exist and it doesn't exist. Time doesn't exist in nature but it does exist mathematically. Change is the reason for the birth of time. If there was no change, time would have never been INVENTED.

Change is natural and no one can deny that. When changes occur it occurs stage by stage, but when man came to think how long would that change last or what is the duration between one stage of the change to the other he found difficulty in expressing it and it was at that point that time came into play.

If a botanist did not want to know or tell what is the life duration of a plant or a tree etc he wouldn't need time, if a electrical engineer did not want to know for how long a bulb of particular power would glow he doesn't need time. So, time was invented in order to know the duration of change or the rate of change.

If one tells how fast a train goes from one station to the other then he actually expresses the change in the location of the train from one station to the other and in order to express that change he used time. Consider I'm buying an ups(uninterrupted power supply) I would want to know how long the charge in the battery of the ups would last when I do not have the power supply so what I do is I use time to tell the duration or the rate of change at which the batter would discharge its potential from full to zero and again to charge from zero to full.

So time arose only when we had the necessity to express the rate of change. I would say that time was invented for our convenience to express change. But then again this is just my personnel view.

To believe that time came into existence as a necessary consequence of our existence seems a bit egocentric. I have a belief that what goes around comes around.

On LinkedIn there is a "What is Time?" discussion that has been stretching on for years.
Recently I purchased Spacetime.University and Time.University.
I plan to host information about spacetime and quantum physics related to time.

Time existing because of our existence is a possibility
if you assume time is essentially an aspect of perception
rather than something required by the continuum.