Superman's speed?

Question

I have a feat where he travels to Earth from the "end of the universe". I'm wanting to low-ball this to what we know. So what's the acceleration of Superman if he went from the observable universe (46.5 billion light years) to Earth in 60 days? Is this still applicable given we don't have any information regarding anything in between that time?

Answer 1

You probably meant to ask for the speed.

 

For a straight-line path, his average speed would be

 

v = x/t

 

= (46.5 × 10⁹ ly) / 60 d

 

= (46.5 × 10⁹ ly) / [(60 d)(1/365.2564 yr/d)]

 

= 46.5 × 10⁹ ly / (0.164 yr)

 

= 284 × 10⁹ c

 

284 billion speeds of light is a lot.

 

The acceleration may vary so we can't say anything meaningful about it from the information given.

Answer 2

You will probably get some trouble unless you specify the universe's 'edge position' and the earth remain constant in your equation.  You also need to identify whether this is an acceleration question or a fixed speed question.  If acceleration, is the change constant? If speed, units do you want to use?  MPH or Light Years (which is, itself, a measurement of speed as well).