Many people say to me the bandwidth of a continuous wave carrier cannot be zero Hertz (time domain only).  If there is bandwidth does this change with frequency.

When we look at the night sky, we see the stars in the past - the further the star, the further into the past it is. As everything is moving about, many of our favorite stars have probably moved vast distances, since emitting the light we now see. Has anyone ever made a map of where everything is right now?

I seem to remember reading at university that light was affected by gravity and was proven by an experiment where the sun would "bend" light allowing stars that should be obscured by the sun to be seen. I have read that photons are massless, so, is it the EM radiation that is affected by gravity and if so surely that would prove that light had mass.

If two spaceships departed from a planet and accelerated away from the planet in opposite directions until reaching 3/4 the speed of light would it be possible for them to send an electromagnetic (light) signal between each other?

I can see two possible answers but am unable to pick between them

1)  The spaceships are moving faster than the speed of light relative to each other and so no signal can be passed between them

2)  A signal could be sent from ship A to the home planet and then retransmitted to ship B, in this situation light would never travel faster than c.

It's common to speak of 'thousands of kilometres', but no one ever says 'megametres' or 'gigametres'.  Why is this? Is it official, or just a convention?  Would it be linguistically correct to say the Earth is about 150 gigametres from the Sun? 

I guess the same could apply to kilograms, but here there's a separate unit, the tonne.  Would it be technically correct to refer to the universe being '13.7 gigayears old?   Is there any consistent official nomenclature across ISO measures for very large numbers?

Added 9/5/12: Since asking this question I noticed that Arthur C. Clarke used the term 'gigayears' and other ISO prefixes in some of his books.  

The first answer below uses the argument that saying things like 'yottameters' is not used simply because it's odd. I don't buy that. Even metres and litres sounded odd to me, and 'gigabytes' still does. (I still pronounce it with a soft G or J, as in gigantic, and will always say 'concert', because a music 'gig' sounds silly to me.  But of course, sounding silly is no scientific argument against adopting a word or pronunciation.

wiil not the piece attach to the maget only after eight years i.e. 4 light years for the energy to reach the iron and 4 light years to come back.

let us consider an object which consists of the 7 colors. now all the seven colors having different refractive indexes of their own will meet at different points. but to see the all the colors the intersection must be at the retina. so only one of the color must be seen, isn't it?

Although travelling at the speed of light is considered an impossibility jut hypthetically if you did look out the window of a spaceship whilst moving at lightspeed, what would you see?

For my A-Levels I have been studying Pascals triangle, and I found that if you select any of the numbers from each prime number row, and divide this by the row number it is ALWAYS an integer. My maths teacher and I are stumped, any help would be appreciated.