The Times Australia
Mirvac Harbourside
The Times World News

.

what would happen if someone moved at twice the speed of light?

  • Written by Sam Baron, Associate professor, Australian Catholic University

I’m curious about what will happen if, hypothetically, someone moves with speed (that is) twice the speed of light? – Devanshi, age 13, Mumbai

what would happen if someone moved at twice the speed of light?

Hi Devanshi! Thanks for this great question.

As far as we know, it’s not possible for a person to move at twice the speed of light. In fact, it’s not possible for any object with the kind of mass you or I have to move faster than the speed of light.

However, for certain strange particles, travelling at twice the speed of light might be possible – and it might send those particles back in time.

A universal speed limit

One of our best physical theories at the moment is the theory of relativity[1], developed by Albert Einstein. According to this theory, the speed of light operates as a universal speed limit on anything with mass.

Specifically, relativity tells us that nothing with mass can accelerate past the speed of light.

To accelerate an object with mass, we have to add energy. The faster we want the object to go, the more energy we’ll need.

The equations of relativity tell us that anything with mass – regardless of how much mass it has – would require an infinite amount of energy to be accelerated to the speed of light.

But all of the sources of energy we know of are finite: they are limited in some respect.

Indeed, it’s plausible the Universe only contains a finite amount of energy. That would mean there isn’t enough energy in the Universe to accelerate something with mass up to the speed of light.

Since you and I have mass, don’t expect to be travelling at twice the speed of light anytime soon.

Blue beams of light rushing past signify a fast moving object going through space
According to Einstein, nothing bulky such as an object or human could accelerate faster than the speed of light. Shutterstock

Tachyons

This universal speed limit applies to anything with what we might call “ordinary mass”.

There are, however, hypothetical particles called tachyons[2] with a special kind of mass called “imaginary mass”.

There is no evidence tachyons exist. But according to relativity, their possible existence can’t be ruled out.

If they do exist, tachyons must always be travelling faster than the speed of light. Just as something with ordinary mass can’t be accelerated past the speed of light, tachyons can’t be slowed down to below the speed of light.

Some physicists believe that if tachyons exist, they would constantly be travelling backwards in time. This is why tachyons are associated with time travel in many science fiction books and movies.

There are ideas that we might someday harness tachyons to build a time machine[3]. But for now this remains a distant dream, as we don’t have the ability to detect potential tachyons.

Read more: Curious Kids: is time travel possible for humans?[4]

Shortcuts?

It’s disappointing we can’t travel faster than the speed of light. The nearest star to us, other than the Sun, is 4.35 light years away. So, travelling at the speed of light, it would take more than four years to get there.

The farthest star[5] we’ve ever detected is 28 billion light years away. So you can pretty much give up on charting the entire Universe.

That said, relativity does allow for the existence of “wormholes[6]”.

A wormhole is a shortcut between any two points in space. While a star might be 4.5 light years away in normal terms, it might only be a few hours away via a wormhole.

If there are any actual wormholes, they would let us travel great distances in a very short period of time – allowing us to get to the farthest reaches of the universe within a single lifetime.

Unfortunately, like tachyons, wormholes remain entirely hypothetical.

Illustration showing a hypothetical wormhole open in space, bending spacetime around it. You can think of a wormhole as a tunnel with two ends opening up to different points in spacetime. Shutterstock

Strange possibilities

Despite the fact we can’t genuinely travel faster than light, we can still try to imagine what it would be like to do so.

By thinking in this way, we are engaging in “counterfactual thinking[7]”. We are considering what things would, or might, be like if reality was different in some way.

There are many different possibilities we could consider, each with a different set of physical principles.

So we can’t say with any certainty what would happen if we were able to travel faster than light. At best, we can guess what might happen. Would we start to travel back in time, as some scientists think tachyons might do?

I’ll leave it to you and your imagination to come up with some ideas!

References

  1. ^ theory of relativity (theconversation.com)
  2. ^ tachyons (www.space.com)
  3. ^ build a time machine (theconversation.com)
  4. ^ Curious Kids: is time travel possible for humans? (theconversation.com)
  5. ^ farthest star (theconversation.com)
  6. ^ wormholes (theconversation.com)
  7. ^ counterfactual thinking (www.reddit.com)

Read more https://theconversation.com/curious-kids-what-would-happen-if-someone-moved-at-twice-the-speed-of-light-183043

Mirvac Harbourside

Times Magazine

YepAI Joins Victoria's AI Trade Mission to Singapore for Big Data & AI World Asia 2025

YepAI, a Melbourne-based leader in enterprise artificial intelligence solutions, announced today...

Building a Strong Online Presence with Katoomba Web Design

Katoomba web design is more than just creating a website that looks good—it’s about building an onli...

September Sunset Polo

International Polo Tour To Bridge Historic Sport, Life-Changing Philanthropy, and Breath-Taking Beau...

5 Ways Microsoft Fabric Simplifies Your Data Analytics Workflow

In today's data-driven world, businesses are constantly seeking ways to streamline their data anal...

7 Questions to Ask Before You Sign IT Support Companies in Sydney

Choosing an IT partner can feel like buying an insurance policy you hope you never need. The right c...

Choosing the Right Legal Aid Lawyer in Sutherland Shire: Key Considerations

Legal aid services play an essential role in ensuring access to justice for all. For people in t...

The Times Features

Macquarie Bank Democratises Agentic AI, Scaling Customer Innovation with Gemini Enterprise

Macquarie’s Banking and Financial Services group (Macquarie Bank), in collaboration with Google ...

Do kids really need vitamin supplements?

Walk down the health aisle of any supermarket and you’ll see shelves lined with brightly packa...

Why is it so shameful to have missing or damaged teeth?

When your teeth and gums are in good condition, you might not even notice their impact on your...

Australian travellers at risk of ATM fee rip-offs according to new data from Wise

Wise, the global technology company building the smartest way to spend and manage money internat...

Does ‘fasted’ cardio help you lose weight? Here’s the science

Every few years, the concept of fasted exercise training pops up all over social media. Faste...

How Music and Culture Are Shaping Family Road Trips in Australia

School holiday season is here, and Aussies aren’t just hitting the road - they’re following the musi...

The Role of Spinal Physiotherapy in Recovery and Long-Term Wellbeing

Back pain and spinal conditions are among the most common reasons people seek medical support, oft...

Italian Lamb Ragu Recipe: The Best Ragù di Agnello for Pasta

Ciao! It’s Friday night, and the weekend is calling for a little Italian magic. What’s better than t...

It’s OK to use paracetamol in pregnancy. Here’s what the science says about the link with autism

United States President Donald Trump has urged pregnant women[1] to avoid paracetamol except in ...