Sure, and nobody will get tired of that entertainment, start looking for some other kind? Write their own books? use the spare cameras for a little film shooting. Hey with all teh computer skills they are deveoping they might just animate them. Or maybe go old school with recreaational pursuits in a limited environment. Kinda sucks when the population grows ahead of schedule though. How do you estimate how many condoms will be needed for a 50 year flight? Of course they expire in 7 years anyways, so after that... no, i'm sure a few old videos will completely prevent cultural divergence.

I didn't say they would 'completely prevent cultural divergence'. I said that it would be trivial to have them available.

They would contribute to reducing cultural divergence, particularly if selected with that goal in mind, rather than simply throwing everything available on a few hard drives regardless of message, but my point was more to the effect that, in addition to being ridiculously impractical to continue streaming content from earth, much of that content's purpose (entertainment) could be accomplished at far lesser effort.
And yes, with sufficient population and resources, the ship's crew could begin to create substantial quantities of their own entertainment media, but that would likely take some time to establish, unless crew were specifically selected to fill that role from launch (not a role I would expect would rise to great priority in the eyes of the funding body).

I have to say that I have serious doubts about the abilities of anyone establishing a space mission of this magnitude also having the ability to effectively select videos that would stymie cultural divergance, aside from the fact that new entertainment and cultural drift will most certainly still be occuring back on earth.

I don't see a problem with streaming massive amounts of information to the ship. The ship doesn't need to expend the power to send it, only a little bit to enhance/decode it upon arrival. It would only be a small additional cost to send out a couple of small unmanned ships at slower speeds to act as signal enhancers.

What percentage of the planetary GDP do you think we are willing to commit to this project? I have seen projects fail or wind up in court over additional expenditures beyond the initial scope which were *much* smaller as a percentage than what you propose. To have a second, unmanned ship traveling at half the speed would still cost perhaps 25% as much as the initial ship (the engines would still have to be far more powerfull than anything we are using today) If you want it to stop halfway there to be used as a permenant beacon perhaps more...

I don't agree with the 25%. Sending an advanced robot to Mars is several orders of magnitude cheaper than sending a couple of astronauts. The beacon would be an engine, fuel, an antenna and a tiny piece of very simple electronics, slightly overdimensioned to withstand radiation. Let's assume the largest cost is the fuel. The beacon needs less then half of the fuel per kg useful load, which is perhaps only 100 kg. That's a speck of dust compared to the weight of the colony ship. The engine would be less powerful by the same factor. That doesn't even take into account that most of the fuel is used to propel the other fuel. I think 1% of the cost would already be an overestimate.

Edit: the real question here is: will taking a larger, more powerful antenna and more fuel to power and propel it on the colony ship be cheaper than sending a couple of smaller unmanned ships or not. This additional fuel also needs to be propelled, so you'd need even more fuel.

@TW Teczka - you're porobably right, though I'd argue that it may not be defrosted so much as 'grown' but in either event we still run into the same problem being battered about now, namely who or whatever gets to stars wouldn't be us, at least not in any recognizeable way. Granted, if the aim is the propegation of our history of sapience rather than our species it's a fine option, and there are other, better, cheaper methods that line of thought opens the door to - self replicating Von Neuman probes with AI's carrying all of our collected knowledge, for example - but it's kind of an apples/oranges comparison. I mean, we don't say that humans have been to Mars even though we've had various robotic or guide-by-wire exploration platforms on it since the seventies and it's kind of the same principle - an AI packet probe to Alpha Centuari I doesn't mean we've been to Alpha Centuari, just that the things we built have. To what extent that distinction matters quantitatively . . .?

@Silveroak & Tendronai: I think there's an overestimation on the difficulty of sending/recieving data here but why not cut out the difficulty altogether. There are a few hypothetical ship designs such as the Starwisp probes which, rather than having engines aboard ship rely on lightsails propelled by masers fromt he point of origin. It has the benefit of not requiring the ship design to have to bear the energy cost of boosting the mass of it's own fuel and allows for an planetary or solar system spanning infrastructure to collect the power required rather than an individual engine/propulsion unit. Piggybacking data into such a stream would be more or less childs play and the ship would be in constant - albeit time delayed - contact with earth.

Actually, the problem is mentioned in that Starwisp article, if only briefly. It is one of signal cohesion over multiple-lightyear distances. The Starwisp would avoid negative effects from this problem by reaching its cruising velocity before the propulsion-signal is diminished to the point of ineffectuality. Which is to say that it is affected by the problem, but that the results it achieves despite that fact are sufficient for its purposes.

More than that, a ship without meaningful deceleration capacity would have an inherent 'scheduled obsolescence' when serving as a relay point for a mission with a fixed destination. A second, long-term, solution would still be needed if continued contact with earth was a priority.

The problem is that while much of the *weight* may be in teh fuel that won't be where most of teh *cost* is. having an antenna that can recieve and transmit over multiple light year distances is *huge*, and in addition to this you are talking about an engine that can achieve a signifigant (2.5 % for the following ship, 5% for the lead ship) portion of the speed of light, which means an engine that is designed to use a very different fuel than what we use now- if it is some variation on an Orion enginer uranium is ralatively cheap, but building an engine that can harness nuclear blasts to propell a ship will be extreemly expensive. it might well be 1% the size, but that doesn't mean 1% the cost.

Here's another question: What would the crew of our hypothetical ship do when they got to Alpha Cen?

Even if they're heading to a world that's Earthlike in every astrophysical way, they won't be able to live on it. There won't be any plants or animals to eat, or any oxygen to breathe.* Terraforming, aside from taking generations to do, would be so far beyond the abilities of a single ship as to be crazytalk. So, what... They're going to survive reentry, set up a little self-sustaining structure on the surface with the plants they brought, and hang out there 'til they've built an entire new spacefaring civilisation of their own?

* Unless there's alien life, which is a whole other barrel of worms.