:point: reply on more recent thread Aliens ...

Are you suggesting currently understood laws are wrong? — tim wood

Well, are you assuming that GR & QFT, our two most predictive physical theories, are fundamental and (therefore) that "currently understood" physics is complete?

(Caveat: "There is nothing new to be discovered in physics now ..." ~Lord Kelvin, 1900)

My Youtube videos, e.g.,
https://www.youtube.com/watch?v=qTx98PUW6lE
suggest physics is not complete. But whether complete or not, water still freezes at 32F and boils at 212F.

New discoveries may refine current understanding - or may be just new discoveries. But there is not a lot of mileage to be got from supposing that new discoveries will contravene well-established laws.

But whether complete or not, water still freezes at 32F and boils at 212F. — tim wood

Yeah, but you can alter those temperatures that by adding stuff to the water or changing the air pressure.

As you pointed out, the sun has plenty of resources, which we can make use of. So do other planets and moons, in terms of raw minerals and gases. — Marchesk

The sun has plenty of energy, but in order to harness it we need to use the limited resources we have on Earth. Likewise with getting to other planets. The EROEI (energy return on energy invested) may not be be so favorable. Fossil fuels have given us the accumulated benefit of millions of years of solar energy, at a very good EROEI, but as that resource becomes ever more scarce and hence costly to extract, general prosperity and capacity to harness solar energy, not to mention the mineral resources of other planets will inexorably decline. I think you've been taking science fiction too seriously; it is fiction after all!

I think you've been taking science fiction too seriously; it is fiction after all! — Janus

It's not all science fiction, since there are some organizations like NASA and SpaceX researching such matters. Maybe the pessimists are right and we are nearing the peak of human technological progress. But my guess is that if we make it out of this century, we'll a lot of time to figure things out.

I don't know; I see the continual rise of technological humanity as inevitably leading to the degradation of soils, destruction of habitats and extinction species; which which all ultimately be to our own detriment and possibly demise.

What exactly are you arguing?

They never do - well-established laws (e.g. Newtonian gravity, Torricellian vacuum), however, have been, and will again be, extended by new discoveries. Btw, either 'space warp' (Kip Thorne, et al) or 'wormhole' (Einstein-Rosen bridge) used as relativistic transit media is consistent in principle with currently understood physical laws ... just as e.g. 'atomic bombs' and 'nuclear reactors' were decades beforehand in 1905 (Einstein).

What you're missing is that what you call well-established laws are approximations to deeper laws. It's both true that we can still use Newtonian physics adequately for a broad range of problems and that QM allowed us to squeeze out far more practical applications (such as being the basis of all modern electronics) We know GR & QM are approximations because we need a theory of Quantum Gravity to explain a number of phenomenon.

&

What you're missing — Saphsin

Not missing. The word for the day is violate. I take it as a given rule that what we know today will not be violated tomorrow. The suggestion that anything is possible violates that rule. Our question then devolves to whether or not certain sci-fi-fantasy conjectures are consistent with current knowledge, the absolute presupposition here being that there is such a thing as knowledge and that we collectively possess some of it.

And the consistency being either practical or principled. It may be, for example, that there is nothing in principle that prevents me, naked in my person, from being able to fly if I just flap my arms somewhere between 20 to 500 times per second. But is anyone going to suggest that's possible?

The wheel was invented, or discovered, a long time ago. Since then vast refinements in wheels. But no improvement/refinement/or subsequent discovery is ever going to "unwheel" the wheel. Theories, of course, are different animals, being essentially descriptive, and by parts, those of gravity being examples. But at the same time we know some things about what we call gravity.

All this goes to what we might call the rule of knowledge, leaving the question whether what we take as knowledge, is knowledge.

I have taken a mini-survey of Youtube videos on faster-than-light travel. There appears a consensus of sorts. Conjectural possibility in some respects, at the expense of disregarding others, and impossibility both as a practical matter and in principle, all the principles taken into account. E.g., sure, according to one, if you have a lot, really a whole lot, of negative energy - which she regretfully informs us does not exist.

An old textbook, which I cannot find, listed and addressed the engineering problems in some detail. Travelling at relativistic speeds means the world - the universe - is coming at you very fast, the exact equivalent of a very high energy flux. Which means shielding, which means increased energy demands to achieve high speeds; the analysis showing that above some relatively slow speed, the combined problems become intractable. Of course nothing that a very few tons of unobtanium or impossibilium couldn't fix!

Or "bending" space and then travelling some kind of rhumb line through it. We all bend space a little bit. But if it takes a village to make a difference, then it takes a star - putting one of those in traces a whole other set of problems.

This is such a laughably uncharitable take of what I was trying to get at. I’m not going to engage with those having a conversation only to themselves.

How so? You said i was missing something and for clarity's sake I laid out why I think I am not missing it - all charity for the benefit of clarity, yes?

How about shielding? If the question does not make sense, then you're out of your depth. — tim wood

Lazors!

this is true. The question begs itself, however unanswerable it may be, to be: is there understanding of physics that make space travel possible? — god must be atheist

We have humans traveling in space right now, so I don't really understand the argument that it's impossible. It'd take very long to get to any other solar system, but that is only a problem if you expect the people leaving to also be the people arriving.

I don't know; I see the continual rise of technological humanity as inevitably leading to the degradation of soils, destruction of habitats and extinction species; which which all ultimately be to our own detriment and possibly demise. — Janus

Space exploration isn't really something that requires a continual rise though. In a way, it would actually benefit from a shift away from continual growth and towards focusing our collective efforts on non-commercial interests.

Space exploration is hugely expensive; wouldn't it be better to spend that money on health care, cleaning up the environment, feeding the hungry, education, reducing poverty and so on?

Why not both? NASA's budget in 2020 is $22.6 billion. The US Federal budget is $4.79 trillion. The European space budget is like $15.2 billion.

I'm not seeing a significant amount of funding going into space exploration. And it tends to pay off in technological advances and scientific discovery. Plus exploration is fundamental part of being human.

We could have started doing any of those things at any time, and of course plenty of people do try to do their part. However many of the issues you name are at the heart of our systems of production, and it's simply not practical to "spend the money". Lack of resources isn't the core problem here, it's that we build our system on the exploitation of the poor and the environment. We could all decide to equalise the world's standards of living, but good luck getting popular support for that in any industrialised country.

Incidentally, it's that same system that has caused space exploration to be relegated to a minor effort, even though it's both inspiring and potentially vital for survival. So I think the goals are actually compatible. Breaking out of the capitalist logic would enable us to both protect this planet and find other ways to live. Getting it started might help people have visions for the future again, something that people in the west at least seem to have forgotten to do.

A SETI researcher's 2 bit(coin)s ...
https://www.theguardian.com/commentisfree/2021/jun/14/aliens-resemble-ai-not-green-martians

Btw, deep space travel is for machines -- the tinier the better -- Von Neumann self-replicating/nano-fabricators (e.g. Bracewell Probes), and not living organisms (re: hard radiation exposure is too lethal, transport size increases likelihood of hazardous particulate impacts, life-support limitations & extreme durations between destinations, etc which exponentially compound the costs/risks). — 180 Proof