Could aliens ever visit Earth?

On 6/8/2026 at 1:41 AM, TheVat said:

Or the actual money available.

I think there is no decoupling the costs of such goals from the economics of the greater economy that is trying to do them.

Economics is about how resources are managed and marshaled to do the things we want from available resources. And absence of positive economics of the intended goal seems as likely to lead to failure as resource shortfalls (I suppose it is a resource shortfall) and technological inadequacies.

15 hours ago, Moontanman said:

Thanks, see what you mean, but wouldn't the efficiency of the engine at least cut down on reaction mass required to reach a certain speed

Yes but it seems very likely to add significantly to the dry mass/dead weight that has to be carried and accelerated.

I had thought ion engines - the most efficient in terms of impulse for reaction mass ejected - would be used a lot more but the mass of hardware needed undercuts the gains.I doubt one of the favoured reaction mass types - Xenon - is going to be easily obtainable, so what gets used may be less than ideal. Such rockets must also include an energy source. Chemical rocket hardware can be low mass and disposable. I doubt nuclear will be like that.

Do the "Orion" types (the "Orion Shall Rise" type) - riding on top of nuclear detonations - rely on the gradual vaporisation of the blast plate between the ship and the blasts to provide some of the thrust? I think that plate (whatever it is named) would be consumed one way or another.

Apart from anything else long term self reliant survival within a closed system - something we can study experimentally here on Earth - has not been demonstrated. The slower the journey the longer that closed system must last.

Sending robotic miners and factories ahead to make supplies and boost them to reach the main ship sounds hypothetically possible - with imaginary technologies much more advanced than we have. Then you would have to carry such equipment - more payload - and have big velocity differences for those supply tenders to overcome, over and over. It all starts sounding harder the more I think about it.

Edited 6 hours ago6 hr by Ken Fabian