Alpha centuri .4 light year relative to who?

In summary: I think I need to do more research on the subject.In summary, a high school student is asking about how long it would take to travel to Alpha Centauri at the speed of light, and how long it would take to arrive at that destination if traveling at a slower speed. According to the information provided, it would take about 16 hours to reach Alpha Centauri at the speed of light, but it would take about a month or two of travel at 1 gee to reach 0.999 c, which is the speed of light.
  • #1
matttan
25
0
Alpha centuri...4 light year relative to who?

Hi,

Here it goes.

Suppose it takes 4 light years to get to alpha centuri.

So if I could travel at 99.99999% the speed of light and the people on Earth remains stationary(as in moving very slowly which is << C).

So does my clock shows 4 years when I get to alpha centuri or the clock on the Earth shows 4 years.

I am a high school student so if possible avoid any technical explanation

Thanks
 
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  • #2


matttan said:
Hi,

Here it goes.

Suppose it takes 4 light years to get to alpha centuri.

So if I could travel at 99.99999% the speed of light and the people on Earth remains stationary(as in moving very slowly which is << C).

So does my clock shows 4 light years when I get to alpha centuri or the clock on the Earth shows 4 light years.

I am a high school student so if possible avoid any technical explanation

Thanks

A light year is a distance, not a time. A light year is the distance that light travels in a year.

Could you please rephrase your question, so that times are in years, and distances are in light years? Thanks.
 
  • #3


Uhh, assuming (which I think you mean to) years instead of light years, the trip takes about sixteen hours for an observer moving at 99.99999.
 
  • #4


Nabeshin said:
Uhh, assuming (which I think you mean to) years instead of light years, the trip takes about sixteen hours for an observer moving at 99.99999.

Yeah that's what I mean. So the time on Earth measured is 4 years?
 
  • #5


matttan said:
Yeah that's what I mean. So the time on Earth measured is 4 years?
Yes, if we assume the distance from Earth to Alpha Centauri is exactly 4 light years in Earth's frame, and the ship is moving at 0.9999999c in Earth's frame, the time in Earth's frame is 4/0.9999999 years which is just a smidge over 4 years (around 4 years and 13 seconds!)
 
  • #6


The time onboard ship would be almost 16 hours.

A problem arises because accelerating to that speed takes a lot of distance & time or very high acceleration. If you did it in 1 hour of ship-time the acceleration would be over 71,000 gees - very unhealthy for all on board. Even accelerating for a year the acceleration required would be over 8 gees.
 
  • #7


qraal said:
The time onboard ship would be almost 16 hours.

A problem arises because accelerating to that speed takes a lot of distance & time or very high acceleration. If you did it in 1 hour of ship-time the acceleration would be over 71,000 gees - very unhealthy for all on board. Even accelerating for a year the acceleration required would be over 8 gees.

Well, 99.99999% of c might be tough but I'd calced a way back that getting to 99.9% c only takes a month or two at 1G. I'll have to check my numbers again.


Ah right. I was looking at http://www.davesbrain.ca/science/gliese/index.html" , which is 20 light years away and 6 years subjective. So a month or two of acceleration is small change.
 
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  • #8


Does that include decelerating to a stop at alpha centauri or do you just "blow on by"?
 
  • #9


DaveC426913 said:
Well, 99.99999% of c might be tough but I'd calced a way back that getting to 99.9% c only takes a month or two at 1G. I'll have to check my numbers again.


Ah right. I was looking at http://www.davesbrain.ca/science/gliese/index.html" , which is 20 light years away and 6 years subjective. So a month or two of acceleration is small change.

You figured it out, Dave?
 
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  • #10


HallsofIvy said:
Does that include decelerating to a stop at alpha centauri or do you just "blow on by"?
Declerating.
 
  • #11


DaveC426913 said:
Declerating.

DaveC426913 said:
Well, 99.99999% of c might be tough but I'd calced a way back that getting to 99.9% c only takes a month or two at 1G. I'll have to check my numbers again.


Ah right. I was looking at http://www.davesbrain.ca/science/gliese/index.html" , which is 20 light years away and 6 years subjective. So a month or two of acceleration is small change.

Dave, just how did you compute that? Reaching a rapidity equal to c at 1 gee takes a year of subjective time, and that's only a speed of 0.76 c. Getting to 0.999c - a rapidity of 3.8 c - takes somewhat higher gees to cram into a few months.
 
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  • #12


qraal said:
Dave, just how did you compute that? Reaching a rapidity equal to c at 1 gee takes a year of subjective time, and that's only a speed of 0.76 c. Getting to 0.999c - a rapidity of 3.8 c - takes somewhat higher gees to cram into a few months.

You know what? Now I'm not sure.
 

1. What is Alpha Centauri?

Alpha Centauri is the closest star system to Earth, located about 4.37 light years away in the constellation Centaurus. It consists of three stars: Alpha Centauri A, Alpha Centauri B, and Proxima Centauri.

2. How far is Alpha Centauri from Earth?

Alpha Centauri is approximately 4.37 light years away from Earth, which is equivalent to about 25 trillion miles.

3. How long does it take to travel to Alpha Centauri?

With current technology, it would take about 137,000 years to reach Alpha Centauri using conventional spacecraft. However, scientists are working on developing faster propulsion systems that could potentially reduce travel time to decades.

4. Is there any life on Alpha Centauri?

There is currently no evidence of life on Alpha Centauri. However, scientists believe that Proxima Centauri, the closest star to Earth in the system, may have a potentially habitable planet called Proxima b. Further research and exploration are needed to confirm this possibility.

5. How is the distance to Alpha Centauri measured?

The distance to Alpha Centauri is measured using the parallax method, which involves observing the change in position of the star relative to other stars as Earth orbits the Sun. This allows scientists to calculate the distance using trigonometry. Other methods, such as spectroscopy and astrometry, are also used to measure the distance to stars.

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