• Question: Why can't anything travel faster than light ?

    Asked by mohamed26 to Nick, Jane, Iain, Chris, Anna on 10 Mar 2014. This question was also asked by , .
    • Photo: Anna Middleton

      Anna Middleton answered on 10 Mar 2014:

      @mohamed26 I haven’t a clue, but what I assume is that stuff probably can travel faster than light but we just can’t see it. But then again its a long time since I did physics so you might be better off asking a physics teacher!

    • Photo: Nick Goldman

      Nick Goldman answered on 13 Mar 2014:

      It’s not my field either, but my understanding is that Einstein’s relativity theory has taught us that nothing can go faster than the speed of light. It would take an infinitely large amount of energy to accelerate anything to that speed.

Comments

  • Photo: Clara

    Clara commented on :

    Hi @mohamed26.

    I’ve snuck over from the Nuclear zone to answer your question (which is a very good one!).

    So in empty space called a vacuum (like in outer space) nothing can travel faster than the universal speed limit, which you rightly called the ‘speed of light’. Light travels at this speed because it has no mass (it doesn’t weigh anything) and so it can zip around the universe very quickly. But other particles (and stuff made up of other particles like space-ships) do have mass and so they do weigh something. This means that they require lots of energy to get up to faster and faster speeds. The closer to the speed of light they get, the more energy is needed to push them even faster, until the energy required is just infinitely too much.

    But, when light travels through stuff, like water or glass, confusingly it doesn’t go at ‘the speed of light’, this universal speed limit, it actually goes slower. So, in this case, sometimes other particles *can* go faster than the light travelling in that stuff. For example, an electron can travel through water faster than light does, even though both of them are going slower than ‘the speed of light’. In this case it will cause a ‘shock wave’ of more light coming from the electron passing through the water, which is called Cherenkov radiation. This effect can be used in nuclear reactors or for many science experiments, such as particle identification in particle physics.

    Hope that answers your question!
    Clara