Adventurous crew may explore the galaxy

This scenario is nearly possible with current technology. A crewed ship could travel the tens of thousands of light years to many far distant stars, explore many planets and return to Earth with current technology. And do so well within the healthily life span of the human crew.

Special relativity allows this possibility but with one catch. And it's a BIG one.

A ship built of concrete, in lunar orbit --

(using moon regolith as aggregate) sufficiently thick in the forward direction of travel could go a long way in mitigating the increasingly potent impacting particles at near light speed. The ship would have to stop once in a while to find material to replenish this "cow catcher."

The propulsion --

could be from a current nuclear power plant such as that of an aircraft carrier. The power output would be sufficient to create a magnetic field redirecting the approaching particles and accelerating them slightly. Even a small acceleration would increase their mass and impart sufficient forward thrust.

(The power provided by a current nuclear aircraft carrier power plant (800 megawatts) is sufficient to accelerate 50,000 lb. at 0.4 g continuously. (check my math someone) Multiple power plants would be needed. The power plant itself each weighs some 8,000 pounds.)

An acceleration of just 1 g will accelerate the craft to 75% of light speed in only 8 hours. Aside from providing a constant Earth like gravity for the crew, the predictions of special relativity would begin having an appreciable effect on time, distance and mass dilation at this point.

Even as the mass of the craft increases according to special relativity, 1 g acceleration could still be maintained relative to the crew, according to special relativity with the same energy output. Frames of reference at rest to the craft, however, would see the craft accelerating more slowly and more slowly, never quite obtaining full light speed.

The crew would, however, see no difference. And would achieve distances of 10,000 light years in what they perceive as only a few weeks. However, 100 centuries would have passed on Earth. The crew could explore many star systems and orbit many planets in their lifetime. They could reach the far side of our galaxy. They could even return to Earth.

However, if they circumnavigate the galaxy before returning to Earth, 3,000 centuries will have passed on the Earth. They may find civilization on Earth was wiped out ages ago or they may find a "welcome home" party awaiting their return.

Or the most exciting possibility, shortly into their journey, they may find an "Earth Space Force" cruiser catch up to them. The intrepid crew may be escorted back to Earth and rewarded for their adventurous spirits with commissions in space fairing Earth vessels which had been developed in the hundreds of years since their departure.

Lets go!!

Jerry

 

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Shit Jerry, where do I sign up?

 

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Your numbers are way off.

First, to accelerate to 75% of c at 1 g takes some 266 days, not 8 hrs.
c= 300,000,000 m/s,
g = 9.8 m/s^2,
v = at or t = v/a

so t = .75(300,000,000)/9.8 = 22959183.67 sec /3600 = 6377.55 hrs/24 = 265.73 days.

Second, your nuclear power plants are not up to the task. 800 MW plant operating for 265 days straight would produce 1.8e16 watt-seconds, or joules, of energy. Even assuming 100% efficiency, this equates to the same energy as your 8000 lb power plant moving at 3146426 m/s or just a little over 1% of c. Given the fact that you won't get anywhere near 100% efficiency, Such a power plant couldn't even get its own mass up to 1% of c in 266 days.

 

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The "Earth Space Force" cruiser would probably pull them over for driving a piece of shit concrete sled.

 

you go, girl!

 

Why concrete?
It's crap in tension and would be rubbish as a structural material.
There are far better materials available to do the job.

 

Can't argue with the math

Can't argue with the numbers, Janus. Thanks for checking my math like I asked.

But 1%c is promising. Isn't it? Lets focus on the principle. I want to hear someone tell me that a craft approaching light speed from a frame of reference at rest isn't moving faster than light from it's own point of view (Namely: a star many light years distant to them at rest is now approaching them with an ETA of merely a few months.)

Geoffp, I think you are right, the "man" will be as ruthless and disregarding of the adventurous spirit as they are today and have been in the past. Those poor adventurous and big spirited blokes would be arrested and fined in the year 2491, for their troubles.

Jerry

 

Return to the days of sailing ships

As far as problems go, there are many more difficulties than just the weight of current technology power plants and 8 hours vs. 8 months of acceleration.

MANY MORE PROBLEMS

There is also the problem of provisions of food, steering and maneuvering during orbital insertion near a distant planet. 1 g will not be sufficient and current rocket technology does not provide for storing enough rocket fuel for any extended maneuvering.

BUT THE IMPORTANT POINT IS

Clearly the most important point here is that special relativity does not say that something can not go faster than the speed of light. It only says that the speed of light is constant regardless of the frame of reference. That will lead humanity to the last and greatest frontier.

A RETURN TO THE DAYS OF TALL SAILING SHIPS

I imagine that instantaneous communication will actually prove a greater challenge than faster than light travel. This will give rise to an amazing circle of events. During the two thousand years of sailing ships, mankind traveled to distant places where the fastest communication to which was a letter aboard a ship. This circumstance will again be the state of man. It is likely the fastest way to communicate with a distant planet is via the next ship heading that way.

Imagine a time when you will have to wait for the next freighter to find the value of your stock portfolio on a distant planet. Or out running your own arrest warrant. However, once embarking on the stars, should we find that others have already populated them, they will likely help us overcome our technologic deficiencies.

Now that is the subject of another thread entirely.

Jerry

 

"Pimp my Spaceship".

 

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drooolz

 

Gonna make your lightspeed ride krunk like thu greys use. Bitchin' concrete sleds.

 

Not really. At 1% of c it would take 430 years just to reach Alpha Centauri, which means you would need a generation ship. Not only that ,but even the 1% figure is overly optimistic.
1. It was arrived at by only considering the mass of the reactor by itself. adding the actual propulsion system, ship superstructure (all that concrete, crew, supplies, fuel to run the reactor, etc, will drop this by several factors

2. Half the energy will go into pushing the particles backwards, leaving only half for propelling the ship forward.

3. Converting reactor power to the magnetic field will not be 100% efficient.

4. Some of the reactor's energy output will be needed to maintain the ship's normal operations (other than propulsion. )

In reality, you wouldn't be able to achieve a significant fraction of even that 1% of c

Be cause of length contraction, the occupants measure the distance to the star as just a few light months. The star will not appear to be approaching at greater than c.

 

Sorry, but that very postulate of the constant speed for light automatically leads to the conclusion that you cannot accelerate a mass even up to the speed of light, let alone beyond it.

 

Uh, the biggest problem with long term space travel is staying alive in deep space. Radiation will kill everyone soon if they're not sufficiently protected. That problem has yet to be solved.

 

Once you are in interstellar space you don't have solar radiation to deal with; no more Coronal Mass Ejections, no more X-rays from the Sun.

But these dangers are replaced by the danger of radiation created by friction with the interstellar medium; and Cosmic Rays are just as frequent as they are in our solar system (once you get outside the protection of Earth's magnetic field, that is.)

5 metres of water would provide a good protection against cosmic rays, according to this paper;
http://arxiv.org/ftp/physics/papers/0610/0610030.pdf
you could put the ship's deceleration fuel and propellant in tanks on the outside of the living quarters, and that would probably be adequate. Or you could use an active magnetic shield, which would require energy for electromagnets (or perhaps superconducting magnets, which might be more efficient).

 

I'm hoping it will be possible to yust send one end of a microwormhole to a nearby star whill hopefully keeping the reactor and fueltanks ad the other end eather on earth or in orbit around the planet thereby keeping the weight down to perhaps 100 kilo or something in that range.
Then when the wormhole arrives it slows down and leakes whatever liquid nano particles to build a bigger facility.
Annyway well first have to see how wormholes behave ones we can create them, but all things considering we might have the essential technology for it before 2100 aftherall we now have the essiential technology to make a anti matter reactor (that doesn't mean we can "actual" practical build one, but we could in theorie)

 

Approximately 15 feet of water offers the same protection as earths atmosphere at roughly 8000 ft of altitude.

 

Oh look. I didn't read far enough...

 

This reminds me of an excellent Sci-Fi novel I read decades ago. A generation ship had been sent to find another habitable planet. Along the way, there was a 'revolution', and half of the population ended up in the high-G region, where they farmed [it was several decks, in a spinning configuration], but forgot their origins, and were trying to discover the laws of physics [every time they moved from one deck upwards to another, the gravity got less!]. The other part of the population [including mutants] had control of the zero-G Command portion of the ship, but also did not know how it worked, though they had views of outer-space. The 'hero' of the story grew up in the farming decks, but was adventurous and re-discovered the control portion of the ship, and eventually learned how to 'escape' by way of the automatic vessels that were designed to detach and go to the newly-discovered planet.

Anyone remember that story, or the name of the book?

 

Great paper! Thanks.