The speed of light

[dig deep]

When astronoms today say that they can look back in time , almost up to 12 biljon years, as they catch the fading light from a very distant galax it must be a very strange statement. As the lights from that galax took 12 biljon years to reach us it means, as they say, that we see the start of the Big Bang (well almost) They also say that all galaxies are moving away from us at a startling speed.

Now, if every galax is heading away from us then the guys from the old days was risght when they said that Earth is the center of the Universe. The Earth must been the starting point We are the Big Bangers

 

[PaulR]

Now, if every galaxy is heading away from us then the guys from the old days was risght when they said that Earth is the center of the Universe. The Earth must been the starting point We are the Big Bangers

No. Apart from some local anomalies, all the galaxies are moving away from each other - there is no centre to speak of.

As an analogy think of a balloon with dots printed on it. As it is inflated they all move away from each other. This is expnding in 2 dimensions, the universe is the same but in 3 dimensions.

Also, shouldn't this be in Einstein's Corner?

 

[Topper]

Tis now in Einstein's but isn't a balloon 3 dimensional?

 

[PaulR]

Yes, but the surface isn't. If you like a 3D analogy thinhk of a current cake rising and the currents moving apart. ;)

 

[dig deep]

Thank´s for the move mate Didn´t find Einstein

BTW guys How fast is the speed of light ?

If U have a fast spaceship, let us say , doing 200000km/sec (thats 2/3 of the speed) and /hahaha/ U lit a flashlite (we are assuming that all the engines are off)

How fast is that beam ? Sure U all know that it is doing 300000km/sec

from a starting point of 200000 This is a rush

So, the problem we face here is Where is the zero point

Same goes for the Big Bank Zero Point. If U look at a map of the existing Universe U can´t see no starting point.

So ?

 

[PaulR]

This is bit difficult as some of the answer is not intuitive (but not nearly as not-obvious as when we deal with answers to quantum theory!).

The first thing is that Einstein postulated is that speed is always relative. Next he said that the speed of light is fixed and, therefore, other factors must change if it appears that the speed of something would be faster.

So, inside the spaceship the light will leave the torch at a speed of 300,000 km/sec relative to yourself inside the ship. If the light goes outside of the ship then to an observer as the ship goes past it's still travelling at 300,000 km/sec but what has changed is the colour of the light. This is the Doppler shift in action (think train whistle changing note as it speeds towards you and then goes past).

As for the starting point of the universe I think it's been covered in another post in this section.