# Is blue shift a potential problem for near light speed travel?

1. Jun 6, 2010

### superpaul3000

I've heard that future spaceships traveling at near the speed of light will have to deal with massive amounts of radiation due to interstellar gas. I think these spaceships might also have to deal with radiation from star light being blue shifted. How close to the speed of light would one have to get in order for the little bit of star light that exists to be blue shifted to gamma rays? What energy would the photons need to be blue shifted to so that they would become deadly to humans?

2. Jun 6, 2010

### cragar

Doppler effect .

lambda=sqrt((1-q)/(1+q))*(lambda2)
where q=v/c and lambda is the final shifted wavelength and lambda2 is the initial wavelength , so you could then calculate how fast you would need to go to shift the light from blue light to gamma rays .

3. Jun 6, 2010

### Mu naught

Using the max precision my calculator goes to (not sure what that is) I get q = 1, so you'd have to be going extremely close to the speed of light.

4. Jun 6, 2010

### cragar

yes you would

5. Jun 7, 2010

### superpaul3000

I guess this would not be that big of a problem until the spaceship got near a star. Given the amount of light incoming from the stars in the night sky it would take 370,000 years for a human to aquire the lethal radiation dosage (if they are traveling at 0.9992c which would blue shift star light to x rays). However traveling at that speed toward the sun, at 1 AU you would get the lethal dosage in 0.005 seconds.