• Question: is it impossible to build a machine that could travel in the speed of light?

    Asked by 595nepk48 to Ed, Kerrianne, Nina, Oli, yoyehudi on 6 Nov 2017.
    • Photo: Oli Wilson

      Oli Wilson answered on 6 Nov 2017:

      Firstly, I’m not a physicist – when I did it at A-level my teacher would occasionally tell me to tune out, explain something to the rest of the class, then show me a board covered in equations and tell me they proved something was true. But based on what I do know, I think it probably is impossible. So much weird stuff starts happening when you go that fast! One website I absolutely love is what-if.xkcd.com. The guy who runs it does know a lot about physics, and he sometimes spends time answering weird questions with serious science. The first one he did was about a baseball thrown at 90% of the speed of light – I won’t give away the answer (hint, it does not end well), but I think all the problems he discusses show why it’d be so hard to travel so fast! Have a read of the article here: https://what-if.xkcd.com/1/

    • Photo: Kerrianne Harrington

      Kerrianne Harrington answered on 6 Nov 2017:

      I talked about this with other physicists over coffee, and this is always a fun question to ask. Because our sensible answer is “I don’t think it is possible”, but the answer we want to give is “maybe we’re wrong and we can do it one day? black holes? wormholes? spaceships?”, because we’ve all grown up with fantastic sci-fi that just takes the ability to do this as a given.

      The speed of light is basically the speed limit of the universe. It’s constant, and the same for everybody no matter how fast they are moving. As things travel faster, their mass increases. If you’ve ever seen the famous equation, E = mc^2, this is the equation that tells us how difficult it is to travel as fast as light. Mass and energy can be changed into one another, so the more energy an object has due to its motion, the more its mass will increase compared to when it was not moving. You don’t really notice this unless you’re travelling really, really fast though! The faster the object goes, the more mass it has, and so the more energy we have to put into it to make it travel even faster.

      A machine that travels the speed of light would need an impossible increase in energy to move it, so it’s unlikely that we will get any normal object to travel the speed of light.

      I also agree with Oli, check out xkcd! The baseball problem is a really fun article!

    • Photo: Ed Bracey

      Ed Bracey answered on 6 Nov 2017:

      I understand far more about squishy things like brains and bodies, not physics! It’s the next thing on my to do list of things to learn.

      From my basic understanding of it, apparently not.

      I think the ideas for super fast travel are based around kind of taking short cuts.

      One way would be to fold space time so you bring two point in space together and then skip across them. Some people think tunnels between two points in space might exist or could be created – they call these wormholes.

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