50 replies to this topic

[Delacorr]

                                                      What would happen if you were traveling faster than the speed of light and were to look behind you? Would you see the light trailing behind or what? Would you be suspended in time and space?

What are your thoughts?                                                      

[Homer]

                                                      The only time I travel faster than light, is when I’m on my way to see my darlin’

When that happens, I’m only looking ahead
                                                      

[Saru]

                                                      Delacorr,

I'm not sure anyone can give you an answer to that, the best we can do is speculate, but there is no definitive answer.

If a spacecraft lets say, was travelling at a speed comparable to that of light, then time, to the astronauts on board, will be going at a different rate from time on the earth. So at a sufficient speed, whereas 50 years may pass on the earth, the astronauts in the spacecraft may have only aged 5 years.

If we then crank up the speed to the speed of light ( if it's at all possible ), we can only guess at to what will happen inside the spacecraft. Time may not pass at all for the astronauts, basically meaning that no matter how long they travel for from the perspective of someone on earth, no time at all will pass for those on board.

If you then exceeded the speed of light, who knows. They probably wouldn't be suspended in space, but inside the craft, time could actually be going backwards. If that's the case, they'd be younger when they got to their destination that when they left the earth, even if they'd been going for 3 million years.

It's really quite bizarre when you think about it.

                                                      

[Althalus]

                                                      Ok this may seem like a thick question, but, why can we not go the speed of light, and I know about E=MC2.

After all, If light can travel at that speed why can't we?

If the answer is, that light has no mass, I would say that it does, otherwise we would not able to see it.                                                      

[Halo_Jones]

                                                       Ooopppps wondered in to the Brain pain zone.                                                        

[Saru]

                                                      Al,

The reason we can't reach the speed of light, is because the closer we get to that speed, the greater the mass of the object becomes. Therefore the energy needed to accelerate the object to a greater speed becomes proportionally greater aswell. Eventually the mass goes to infinity - requiring an infinite amount of energy to get the speed of the object any higher. Because of this it is thought impossible to actually travel at the speed of light itself.

I'm not convinced it is known for a fact whether or not light has mass. Visible light, which is part of the electromagnetic spectrum, consists of 'photons', and it is generally thought that photons do not have mass.                                                      

[Aslan]

                                                      But the speed of light is not infinite, so an infinite amount of energy is therefore not required. The difference between an infinite amount of energy and just a vast amount of energy is, well, infinite.

So if not an infinite amount of energy, how much energy would it actually take?                                                      

[Saru]

                                                      Aslan,

The speed of light is not infinite as you say, but the mass of the object your trying to move at the speed of light becomes infinite as it approaches light speed.

It is to further accelerate this object of infinite mass that you need the infinite energy for. Since an infinite amount of energy is not available, nothing with non-zero mass can ever reach the speed of light itself, as far as we know.                                                      

[Aslan]

                                                      Aha. Got it.

I'm still a little fuzzy on just WHY the object would attain infinite mass. The whole concept of gaining mass with speed I understand, but INFINITE mass?

I can't quite grasp how something finite can slowly become infinite, for whatever reason.                                                      

[Saru]

                                                      I agree, I don't think anyone really knows why it happens either.

Similarly there's no real explanation for why the faster an object is moving, the slower time passes for that object, and the shorter that object becomes.                                                      

[Aslan]

                                                      

QUOTE

Similarly there's no real explanation for why the faster an object is moving, the slower time passes for that object, and the shorter that object becomes.

Is that true for sound and light waves aswell?

(And if that quote from SaRuMaN doesn't come out right, could someonw tell me how to quote. Another mystery of the universe.)                                                      

[FreyKade]

                                                      its just like when you are on a rollercoaster, when you go down a slope, very fast, you feel heavier                                                      

[Saru]

                                                      Aslan,

Sound waves are just waves, the speed of sound waves can change depending on the medium the waves are passing through.

Light 'waves' are a controversial subject, as light exhibits behaviour consistent with both waves and particles. 'Photons' are described as being 'chopped up pieces of wave', and are regarded as being what light consists of.

You can't really apply time dialation and length contraction to light or sound, sound waves in particular are not even part of the electromagnetic spectrum. I suspect these phenomena are only applicable to physical objects with non-zero mass.

* Edit - Sorry forgot to mention how to add quotes

You need to have two quote tags on either side of the text you wish to quote.

For example :

CODE

[QUOTE]This is a quote[/QUOTE]

Remember to add a / in the second tag to indicate that it's the end of the quote.                                                      

Edited by SaRuMaN, 18 June 2003 - 07:43 PM.

[Aslan]

                                                      God, it's just bizarre (bizzare?) , isnt it.

So what does sound consist of?

QUOTE

Sound waves are just waves

What does that mean, just waves? And what about other kinds of waves? What do they consist of?

And I still can't grasp how something that exists in an objective sense, as sound waves demonstrably do, can have zero mass.

My father was a physics teacher you know. I'm adopted.                                                      

[Saru]

                                                      Aslan,

Sound waves are basically vibrations, that can travel through a medium such as through air, or through water - but not through a vacuum.

Visible light is a type of electromagnetic wave, which is a wave of oscillating electric and magnetic fields. Other electromagnetic waves include radio waves, microwaves, infra-red waves etc.