What is Time? (And Can We Travel It?)

Time is one of the most familiar yet mysterious aspects of reality. In everyday life, we experience it as a steady flow from past to present to future, but modern physics suggests that time isn’t absolute. Instead, it's woven together with space into a flexible structure called spacetime, which can be stretched and warped by gravity and motion. This raises the possibility that time might not simply “pass,” but could in principle be bent or looped under extreme conditions.

Building on this idea, physicist Ronald Mallett (article linked below) has proposed that rotating energy — such as a circulating ring of laser light — might twist spacetime enough to create what are known as closed time-like curves, essentially paths that loop back into the past. In theory, such a system could function as a kind of time machine. However, there are major limitations: the energy requirements may be enormous, the technology far beyond current capabilities, and crucially, any travel to the past would likely be limited to the point after the machine was first activated.

This leaves us with a fascinating tension between possibility and constraint. Time may not be as fixed as it appears, yet our ability to move through it — especially backward — remains deeply uncertain. The question of time travel, then, sits at the intersection of physics and philosophy: if it’s possible, it challenges our intuitions about causality, free will, and whether the past is something that can ever truly be revisited.

• Is time something that exists independently of humans, or is it a construct based on our perception?
• Is time fundamentally continuous (smooth and unbroken), or could it be discrete, made up of tiny indivisible units?
• The block universe theory suggests that past, present, and future all exist equally. If that’s true, in what sense are we actually “moving” through time rather than simply experiencing different parts of a fixed structure?
• If it became physically possible to travel back in time, should we? Are there moral limits to changing the past?
• Do paradoxes (like changing the past and altering the present) suggest that time travel is impossible, or just that our understanding of causality is incomplete?
• Why do you think the idea of time travel is so compelling across both science and storytelling?

The Scientist Who Lost His Dad and Resolved to Travel to 1955 to Save Him https://www.theguardian.com/science/2023/mar/01/back-to-the-father-the-scientist-who-lost-his-dad-and-resolved-to-travel-to-1955-to-save-him
The Block Universe Theory, Where Time Travel is Possible but Time Passing is an Illusion https://www.abc.net.au/news/science/2018-09-02/block-universe-theory-time-past-present-future-travel/10178386
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