# Thread: Earth-Like planet 20 light years away

2. ## Re: Earth-Like planet 20 light years away

I am packing my skis,

this seems like nice place for winter holidays!

Chances for life on this planet are 100 percent
That is quite bold statement, quickly, we need to send probe there, I will pick one of our older robots and put it aboard!

Petr

3. ## Re: Earth-Like planet 20 light years away

20 lightyears isn't too terribly far away. If there is intelligent life there, they must hate living on only 10% of their planet that won't spin. I mean I would hate that.

4. ## Re: Earth-Like planet 20 light years away

Quickly build space ship with warp engine....

5. ## Re: Earth-Like planet 20 light years away

[font=courier new][size=8pt]I did a quick calculation (it might be correct).

Say, we have a 150 pound (68 kg) man. And he is going to travel to that planet, at 1/5th the speed of light, so that he will get there in 100 years.

How much energy would it take to accelerate him to 1/5th the speed of light?

I did the calculation in terms of gasoline.

The answer was approximately, the energy equivalent to burning 30,700,000 barrels of gasoline.

According to the following link, in 2007, North America consumed approximately 25,000,000 barrels of gasoline per day.

http://tonto.eia.doe.gov/cfapps/ipdb...5&pid=54&aid=2

If, instead, he travels at 1/2 the speed of light, so that he gets there in 40 years, it would require the energy equivalent to burning approximately 230,300,000 barrels of gasoline.

According to the same link, the entire world consumed approximately 86,000,000 barrels of gasoline per day in 2007.

(Remember, that the calculation assumes that only the mass of the man is being accelerated. In the real case, that would not be true. He also has to take along the mass of his spaceship and fuel. I would not be surprised if no spaceship from Earth reaches even the closest star, Proxima Centauri (4.24 light years), during the 21st century. But, that's just my opinion.)

Dan

6. ## Re: Earth-Like planet 20 light years away

Originally Posted by danbaron
[font=courier new][size=8pt]I did a quick calculation (it might be correct).

Say, we have a 150 pound (68 kg) man. And he is going to travel to that planet, at 1/5th the speed of light, so that he will get there in 100 years.

How much energy would it take to accelerate him to 1/5th the speed of light?

I did the calculation in terms of gasoline.

The answer was approximately, the energy equivalent to burning 30,700,000 barrels of gasoline.

According to the following link, in 2007, North America consumed approximately 25,000,000 barrels of gasoline per day.

http://tonto.eia.doe.gov/cfapps/ipdb...5&pid=54&aid=2

If, instead, he travels at 1/2 the speed of light, so that he gets there in 40 years, it would require the energy equivalent to burning approximately 230,300,000 barrels of gasoline.

According to the same link, the entire world consumed approximately 86,000,000 barrels of gasoline per day in 2007.

(Remember, that the calculation assumes that only the mass of the man is being accelerated. In the real case, that would not be true. He also has to take along the mass of his spaceship and fuel. I would not be surprised if no spaceship from Earth reaches even the closest star, Proxima Centauri (4.24 light years), during the 21st century. But, that's just my opinion.)

Dan
Isn't this - the massive amount of fuel required - the reason for space agencies to develop solar sails? I know the Japanese have recently successfully tested one. And I personally know someone working on them in America.

Lance

7. ## Re: Earth-Like planet 20 light years away

Some interesting energy fields at the edge of the Splar system (heliopause).

http://en.wikipedia.org/wiki/Heliosphere

The Solar wind goes up to 1 million KPH but to approach the speed of light you would need to go 10 thousand times faster than this. You need photonic sails to go really fast.

Charles

8. ## Re: Earth-Like planet 20 light years away

[font=courier new][size=8pt]It seems to me that the sails would solve two problems.

1)
You don't have to carry the fuel. The energy-weight ratio for gasoline is relatively terrible. But, I think that even if you used the most efficient nuclear drive, almost all of the mass you are accelerating, would be fuel. Presumably, the farther you went, the more fuel you would use, and the less your vehicle would weigh. On the other hand, if you are making a round trip, then you would still have half of your fuel when you reached your destination.

2)
If the sail is pushed by starlight, then you get the energy for free. (But, apparently, interstellar light is too weak (and it comes from all directions!). Most designs rely on lasers or masers, aimed at the sails from Earth. In that case, you still have to find the energy somewhere - but the energy required would be much much less, since you would not be carrying the fuel, so the mass of the vehicle you would be accelerating, would be much much less.)

(Similar to gravity, the force (attractive for gravity, repulsive for light) is proportional to the inverse of the distance squared. So, if for instance, the power source is a laser or maser, and, at distance 1 light year from Earth the force on the sail is, "F", then at distance 2 light years, the force on the sail would be F/4, at distance 3 light years, the force on the sail would be F/9, etc. (Maybe light sails will be useful, but I don't think anyone will mistake them for warp drives.))

So, say that a craft from Earth lands on the Earth-like planet which is 20 light years away. Then, it would take 20 more years before any transmission from the craft reaches us. I think that the only way humans will survive, is if they fix this planet. I think imagining that we will escape to a better place, is a form of escapism. (On the other hand, who wouldn't want to wave goodbye forever to this place? Wouldn't it be great to see Earth growing smaller and smaller, and then disappear? It's become like a tree covered with insects, only, we're the insects.)

9. ## Re: Earth-Like planet 20 light years away

Originally Posted by danbaron
[font=courier new][size=8pt]It seems to me that the sails would solve two problems.

1)
You don't have to carry the fuel. The energy-weight ratio for gasoline is relatively terrible. But, I think that even if you used the most efficient nuclear drive, almost all of the mass you are accelerating, would be fuel. Presumably, the farther you went, the more fuel you would use, and the less your vehicle would weigh. On the other hand, if you are making a round trip, then you would still have half of your fuel when you reached your destination.

2)
If the sail is pushed by starlight, then you get the energy for free. (But, apparently, interstellar light is too weak (and it comes from all directions!). Most designs rely on lasers or masers, aimed at the sails from Earth. In that case, you still have to find the energy somewhere - but the energy required would be much much less, since you would not be carrying the fuel, so the mass of the vehicle you would be accelerating, would be much much less.)

(Similar to gravity, the force (attractive for gravity, repulsive for light) is proportional to the inverse of the distance squared. So, if for instance, the power source is a laser or maser, and, at distance 1 light year from Earth the force on the sail is, "F", then at distance 2 light years, the force on the sail would be F/4, at distance 3 light years, the force on the sail would be F/9, etc. (Maybe light sails will be useful, but I don't think anyone will mistake them for warp drives.))

So, say that a craft from Earth lands on the Earth-like planet which is 20 light years away. Then, it would take 20 more years before any transmission from the craft reaches us. I think that the only way humans will survive, is if they fix this planet. I think imagining that we will escape to a better place, is a form of escapism. (On the other hand, who wouldn't want to wave goodbye forever to this place? Wouldn't it be great to see Earth growing smaller and smaller, and then disappear? It's become like a tree covered with insects, only, we're the insects.)

I gather that the sails are incredibly large and so have to be made from extremely thin material that is also extremely strong. I also gather that the idea is that the craft powered by the sail would gradually accelerate to until it reached (say) half the speed of light). The idea would be to use the solar wind (which is not so weak) to help with the initial acceleration to a very high speed.

The Japanese have just tested such a sail - apparently successfully. And I know that America has been researching it too. So these people can't believe that they are just wasting their time.

Lance

10. ## Re: Earth-Like planet 20 light years away

[font=courier new][size=8pt]Probably they are not wasting their time. But, I think their research shows that reality and science fiction can be completely different. I've never seen a spaceship in a movie that looked like a giant umbrella. Attached below is a picture of how a real spaceship may look.

I think we can agree that the main roadblock preventing spaceships from approaching light speed is the huge amount of energy required to accelerate them to those speeds. But, there are other problems too. For instance, say that hypothetically, the energy problem has somehow been solved. In that case, will man ever travel at, say, 99% of light speed? I think the answer is, "no". And, in my opinion, the reason is, the increase in mass. If you substitute 0.99 into the equation at this link, http://scienceworld.wolfram.com/phys...sIncrease.html , for beta (v/c), you find that at 99% of light speed, a person's mass is approximately 7 times what it is at rest (but his strength would not have increased at all). In that circumstance, the person could barely move, if at all. And effectively, his heart would be pumping 7 times the blood that it normally pumps, because his blood would have 7 times the inertia (7 times the resistance to being accelerated). Most likely, he would asphyxiate.

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