It would take about 50,000 years for our very fastest spacecraft to get to Alpha Centauri.
Alpha Centauri is the nearest star to our sun. But, at four light years away, it’s much farther away from us than the sun. There’s a lot of empty space between us and this star. If you imagine Earth as small as a grain of sand, then Alpha Centauri would still be over 10 kilometers – or about 6 miles – away.
Of course, in actual fact, Alpha Centauri is millions and millions of miles away from Earth, and it would be almost impossible for spacecraft to travel there.
Consider the speed of the Space Shuttle. Shuttles travel only a few hundred kilometers into space. Again, if Earth were the size of a sand grain, this would be about the width of a hair in contrast to the 10 kilometers to Alpha Centauri. One would need about 10,000 shuttle main engines in sequence just to build up a decent speed (say, 1/100th light speed). So space shuttles are far from being star ships.
About the closest vehicles we have to star ships currently are the Voyager spacecraft – launched from Earth 20 years ago – and now heading out of the solar system. The Voyagers aren’t aimed toward Alpha Centauri, but if they were, they’d take about 50,000 years to get there.
If a propulsion system is developed that can sustain a constant 1g acceleration up to 99.9% of the speed of light, I calculate that it would take about one year ten months from the perspective of the astronauts (taking into account relativistic time dilation) to reach Alpha Centauri, which would be about five years three months to the rest of us on Earth. From the astronauts’ frame of reference, about one year eight months would be under 1g acceleration/deceleration and only two months would be coasting with zero g, which is manageable physiologically. So, with the right propulsion system, it’s at least feasible from an astronaut standpoint.
Of course designing such a propulsion system is not possible given today’s technology, but who knows what might happen in the future? 150 years ago nuclear power was unimaginable. The energy requirements would be enormous and increased by the fact that the mass of the spacecraft would increase due to relativity as its speed increases. At 99.9% of c, the spacecaft mass would be over 22 times its rest mass, so you would need over 22 times the initial thrust in order to maintain the same 1g acceleration. Quite a challenge, but again, 150 years ago no one would have imagined a nuclear powered aircraft carrier or submarine that can cruise the globe for 50 years w/o refueling, so who knows what the future will bring.
David,
You’re forgetting about deceleration.
That’s the trick about it. How long does it take if you want to slow down and visit?
Also, in calculating the time that the astronauts “feel”, you forgot about the aging do to acceleration, both at the beginning and end of the trip. (That’s how to solve the problem of the Twin Paradox.)
David, I thought the increase of mass relative to velocity was exponential, and therefore the energy requirements also increase exponentially. I.e. to travel anywhere close to light speed would require and almost infinite amount of energy and travelling at light speed would require infinite energy and the mass of the craft would also become infinite.
Also as time slows down as you approach light speed relative to an observer, well actually time slows down the faster you go regardless of how close to light speed you travel as has been proven by experiments on earth using a Boeing 757 and a two atomic clocks. Anyways I would have expected the time dilation to be significantly higher than 5 years to 1 year and 10 months; my initial thought with out any maths to back my theory up would be that time dilation would offset the astronauts time frame by 100’s if not thousands of years relative to an observer as rest.
I’m not saying your calculations are wrong; I’m just surprises and wondered if you could post your math equations on here. If your right than they could still be hope for space explanation, although I still believe that development of space folding technology is the way forward; if you can’t beat light speed then cheat it :D
I am no expert on this, however my Professor is [Harvard University]. When asked about the time delation effect when going to Rigel Kent [Alpha Centauri] at 99% the speed of light…He said the occupents inside the craft would age by One hour-14 minutes and 20 seconds. So as you can see, the effects of going near the speed of light are massive.
And on that scale, traveling 80 light years would age you roughly one day, plus or minus a hour or two. So in that sense extremely distant star travel is possible within a human beings lifetime…For you. If you are on the craft and it is going at near light speed. But by the time you arrive at a VERY far off Star system, your folks and friends at home may have already aged 100+ years and are long gone [which is not something anyone on such a craft would want to think about].
[...] miles away, considering at our current technological level it would take us theoretically 85 years (realistically more like 50,000 years) to reach our nearest neighbor, Alpha Centauri, a mere 4 light years away, traveling to Gliese 581g [...]
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I don’t pretend to know this stuff, but i have a question.
For the sake of simplicity, say we have a vessel that can travel at a constant velocity of .5c at 1g acceleration. It maintains a .5c velocity for half the trip with some time at 0g during the journey and at turnaround decelerates to a stop as it enters the AC system. Since the AC system is 4.37 light years away and give or take time accelerating to .5c shouldn’t the journey take about 10 years to an observer? How much time would pass for the traveler?
Of course, this is all based on the initial premise that light does not have mass which I believe we will one day find out to be false. Once mass is given to light, all the equations become much simpler. I figure approximately 355 days at 1g to achieve light speed, 2x light speed in about 2 years, etc.
Furthermore, I don’t believe that mass increases as we approach the speed of light, nor the propulsion needed to accelerate at 1g. So, in my mind, we only need to find a way to sustain 1g with enough feul to last years and we’ll be visiting other stars.
Of course, I have very little formal education on the subject so I’m probably wrong but I’m going to LOL when someone discovers “oh, light does have mass… we no longer need these magical equations to describe what we observe in the universe”
Even geniuses can be wrong.
Someone go make a spaceship so we can test it!!
Already done & thoroughly proven. The only thing you got right was your lack of education on the subject.
You are correct, all matter in the physical universe, stars,planets,comets,asteroids, dust particles, and ourselves included…….is “Light slowed down”
How likely is it that aliens are living among us in order to learn about human social development?…
Monumentally unlikely. First of all, the aliens would have had to travel to us in sub-light-speed ships (because Einstein ruined EVERYTHING!) without being detected by us. I guess they would have had to have come before we had radar, etc. These Aliens …
Contrary to what people would like to believe about time and the speed of light, current accepted theories are a farce. Time dilation experimentation results have been misinterpreted. Time has been credited to dilate, when the obvious is not considered – gravity’s effect on the subatomic particles used to determine a precise measurement of time, and refraction. The speed of light also depends on what point of reference you are measuring the event, and how fast the source of the light is traveling. So, if you were to measure the speed of a light wave traveling away from it’s source that is traveling in the same direction as the light wave at .5c from a fixed point(not moving in any direction) in space, then the speed of the light emission would a be 1.5c from that fixed point.
The fact is the overall effect of LS ( light speed on the human body is unknown) folding space using the gravity of our own star maybe more likely then trying to reach the speed of light.
Some of the factors above make perfect sense but whats left out is passing through black holes at the speed of light by accident , cosmic dust storms and most of all the amount of g force on the human body as well as maintaining sanity for a trip of that length .
The concept of bending or folding space using the gravity of our own sun in a slingshot effect might be one way to reach a black hole known to exist in our own galaxy and pass through that..
I am no expert I can say the a Alien that has found a way to pass through vast expanse of space only to attack us seems rather foolish , in no way to say I mean any disrespect to the great Dr Hawkins but his idea that those creatures meeting us it would be better for us to keep a low profile as when we as humans have met cultures less evolved then us would be the same results does not have a logically meaning to me.
LS is so far off for us at this point it is not even a worry the voyagers would not even reach AC for another 50,000 to 70,000 years and thats out fastest craft ?
LS is a long long way away , much like our closest star
Pass through a black hole? Pass through a massive object with gravitational forces that won’t even let light out? What is lightspeed around such an object? Sounds like everlasting pain to me :P
While the vast majority of experts agree with Eistein that travel beyond light speed is not possible, I feel that this has yet to be proved beyond all doubt. What does appear to have been proved is that “light” can not travel faster than light speed.
If we take this as being true, we run up against one or two problems, when having invented a propulsion system that enables us to travel faster than light.
Firstly we would not be able to see behind us, as any light travelling from that direction, would not be able to catch us.
Secondly, and here my lack of education lets me down, I would presume any light emanating from in front of us would either be too distorted to see or we would be unable to process the information quickly enough to avoid the object from whence the light source had been emitted. In other words we would hit any object before we saw it.
Radar would be no good, as it’s restriction from traveling faster than light speed, would prevent it from leaving our space ship from the direction we were facing.
What we would see looking out of any side window, I have no idea, presumably whatever we saw would be very distorted.
So to sum up. we would be traveling blind, and sooner or later we would hit something and be smashed to smithereens.
Given the countless number of stars in the Universe, mathematically it would seem unlikely we are alone in the Cosmos, but unfortunately it is very unlikely we will get to meet any aliens.
One last question, Why do people say it all started with a “big bang”? Time doesn’t start and doesn’t end. There must have been something before the “big bang” It would seem far more likely to me that there are cycles, with the Universe expanding and collapsing, then expanding again etc etc etc.
P.S. We hear lots of talk about the size of the Universe. It has no size. The Universe exists in space, space is nothing, emptiness. How can nothing start or end.
When I was a young lad I remember reading in a book of mine; I believe it was by ‘Time’ or Timelife. There was a full series about the universe, life under the sea blah blah. But i specifically remember the book stating that in the supposed ’58-years’ an astronaut would age, it would be something like 1 (or 4) Billion years on earth.
I’m desperate to find that book again so I can actually quote it. It was from the very late 80′s when it was published …. therefore take it with a grain of salt.
Joey :)
Everyone keeps forgetting one basic rule of space travel no matter the object, and no matter the objects size. In space whatever is moving keeps moving until something else hits it causing it either slow down, change direction, slowing down while changing diretions, or the most likly one break into smaller pieces all of which go diffrent dirctions at diffrent speeds until hitting something else. This being said why is everyone so set on need a engine to run the whole lagnth of the trip no matter the distance?
All you have to do is get the ship to the speed you desire to go and just simply turn off the engine the ship will coast at that eact speed the whole way or unlil it runs into something. Now that being said you can also do something else which will work. with todays technology if we wanted to do it. You get the ship headed toward it’s destation let the engines reach full speed, turn them off, and then turn them back on. The force of the engines will cause the ship to go faster every time you did this. Now true you would need a lot of fuel to pull it off but it would do it. Than to slow down you just turn on another set of engins to slow the ship down until it stops. Problme solved.
We have the technology we just don’t want to do it that way cause it woud cause more money than NASA has ever accumalated in it’s entire exsistace.