Another light speed one. Hypothetically…

[wildwood]

I am still trying to get my head around this speed of light thingy.

One spaceship can travel at the SoL and goes to the Canis Major Dwarf Galaxy (25000 light years away). Counting onboard time, would it get there in 12500 L.Y. as it meets the light?

[NazNomad]

It's not meeting the light, it's meeting the object ... if the light from that object takes 25000 years to get here, a ship travelling at the speed of light would take 25k years to get there.

If your brother takes 10 minutes to get from Sainsburys to home, and you drive from home to Sainsburys at the same speed, you wouldn't get there in 5 minutes.

[mibn2cweus]

Traveling at the speed of light it would arrive instantly.

[NazNomad]

The speed of light isn't infinite ...

[MarkRae]

No it wouldn't. It would arrive in 25,000 years.

[starone]

If it's 25,000 light years away and it's travelling at the speed of light then it's obviously going to take 25,000 years to get there. Simples.

[naomi24]

No, it's going to take 25,000 light years to get there.

[society]

Wildwood, here's a bit more to confuse you ;-) - http://tinyurl.com/2b5nlu7

[naomi24]

I just looked at a light year conversion chart and apparently 25,000 light years is equal to 146965634329590200 miles. I can't read that number off the top of my head - and it's too late in the day now to attempt to decipher it - but it's quite a long way. :o)

[NazNomad]

You wouldn't want to be sitting with an ''are we there yet?'' passenger, lol

[mibn2cweus]

//No it wouldn't. It would arrive in 25,000 years. //
With reference to the clock at the point of departure it would, but onboard, traveling at the speed of light (although impossible) no time at all would elapse.

[MarkRae]

That simply isn't true.

[NazNomad]

For me ... only just.

[wildwood]

Thank you all so far. I did mention the onboard time on purpose. I did think there might be some discrepancy between the departure time and onboard time.

Thank you Society, I think I am now sorry I asked :-)

Going for a nap now.

[mibn2cweus]

Perhaps this will shed some light on your question . . . http://www.costellosp...e_speed_of_light.html

[jake-the-peg]

Your ship cannot travel at the speed of light but let's say hypothetically it can travel at 99.999% of the speed of light.

The formula is here: http://www.esotericsc....com/timedilation.gif

to is the Earth time v is velocity and c the speeed of light.

Just banging some numbers in B.C. (before coffee) I make that 223 time earth time so a mere 112 years

If you look at the equation you'll see that if you are at the speed of light v=c and you divide by zero

[naomi24]

Mibs, if when travelling at the speed of light theoretically time slows to zero, and therefore our spaceship arrives at its destination instantly, how can the speed of light be measured in time? For example, why doesn't the sun's light reach us instantly rather taking around 8 minutes to arrive?

By the way, did anyone figure out what 146965634329590200 is in words?

[chakka35]

If you use 'bilion' in its proper sense of a million million then you express that number as:

A hundred and fortysix thousand nine hundred and sixtyfive billion six hundred and thirtyfour thousand three hundred and twentynine million five hundred and ninety thousand two hundred.

If you prefer the cheap, plastic and inaccurate version of 'billion' as a thousand million then make the adjustments accordingly.

[vascop]

If you travel at half the speed of light towards something which is 25,000 light years away in a spaceship then the on-board time taken will be 50,000 years. If you travel at the speed of light then on-board time taken will be 50,000 years.

[vascop]

Sorry that last number should be 25,000