“But beyond imagination and storytelling, what does science tell us? Is time travel possible – even in principle,” asks Whimsy columnist CLIVE WILLIAMS.

“These are the good old days. Just you wait and see.” –Steve Turner

Time travel has long fascinated humanity. 

From science fiction stories to blockbuster films, the idea of moving backward or forward through time raises profound questions about physics, causality and free will.

But beyond imagination and storytelling, what does science tell us? Is time travel possible – even in principle?

The answer depends on which direction in time you’re talking about.

Travelling to the future: yes

Traveling into the future is not only possible – it has been experimentally confirmed.

According to Einstein’s theories of relativity, time does not pass at the same rate for everyone. Time slows down for objects moving very fast or experiencing strong gravity.

This effect, known as time dilation, means that someone moving at high speed or living near a massive object ages more slowly.

Astronauts aboard the International Space Station experience this effect. They orbit Earth at about 28,000 kilometres an hour, and as a result, they age very slightly less than people on the ground. The difference is tiny – milliseconds – but it is real and measurable.

In theory, an astronaut traveling near the speed of light could leap far into the future. If they spent a few years aboard a near-light-speed spacecraft, decades or centuries could pass on Earth. When they returned, they would find the future waiting for them.

This form of time travel doesn’t violate physics, doesn’t involve paradoxes, and doesn’t allow a return trip to the past. It’s simply an extreme version of something the universe already allows.

To the past: probably not ever

Traveling backward in time is a very different matter.

Some solutions to Einstein’s equations suggest that backward time travel might be mathematically possible under unproven conditions. These include structures such as wormholes (shortcuts through spacetime), rotating universes, or hypothetical objects such as cosmic strings.

In theory, these could allow “closed time-like curves” – paths that loop back into the past.

However, these ideas require forms of matter or energy that have never been observed, such as negative energy densities, and they would likely be unstable. Even if they could exist, controlling them would be far beyond any conceivable technology.

More importantly, backward time travel creates serious logical problems.

The paradox problem

The most famous issue is the grandfather paradox: if you were to travel back in time and prevent your grandfather from meeting your grandmother, how could you have been born to make the trip in the first place?

Physicists have proposed ways around this, such as the idea that the past is fixed and cannot be changed, or that time travel creates alternate timelines. While intriguing, these solutions remain speculative and unsupported by evidence.

Stephen Hawking famously proposed the “chronology protection conjecture”, suggesting that the laws of physics prevent time travel to the past in order to preserve the world as we know it.

Why physics resists backward time travel

One of the strongest arguments against backward time travel comes from thermodynamics. The universe has a clear arrow of time defined by entropy – the tendency for disorder to increase. Broken cups don’t spontaneously reassemble; memories exist of the past, not the future.

Reversing time would require reversing entropy across entire systems, which appears fundamentally incompatible with known physical laws.

Quantum physics, often invoked in time-travel discussions, does not currently provide a clear escape from these constraints. While quantum effects can blur cause and effect at very small scales, they do not enable macroscopic travel into the past.

So, is time travel possible?

Travel into the future is not only possible but unavoidable – we are all moving into the future at different rates depending on speed and gravity.

However, travel into the past remains in the realm of theory and fiction. While physics allows intriguing mathematical possibilities, there is no evidence that backward time travel could occur, and strong arguments suggest that science actively proscribes it.

Time travel may captivate our imagination, but for now, the future is the only destination science allows us to visit.

On a lighter note: Fred joined a time-travellers’ comedy club, but the jokes were a mess. The punchlines arrived before the setup, the laughter echoed from last week, and the heckling hadn’t happened yet.

Fred told a joke about the future and got booed for something he hadn’t said yet. So, he went back 10 minutes to improve it, only to find himself already apologising.

In the end, he re-scheduled the joke for next Tuesday, cancelled it yesterday, and somehow still managed to offend someone in 2027. 

“The future is not what it used to be.” –Yogi Berra

Clive Williams is a Canberra columnist.

News all day, every day at CityNewsQBN.com.au.