Fun physics problems

Well actually sort of engineering problems.

I was thinking about the fact that in a billion years, life on Earth will become impossible due to the increase in the solar constant (the orbit will grow but not enough). Then I suddenly thought, why not move the Earth? We have plenty of time, but do we have enough energy?

The two sources of energy I considered were sunlight incident on the Earth, and fusion of hydrogen from the oceans. Is either one or both of these adequate to provide an amount of energy similar to the Earth's kinetic energy? What fraction of the ocean is equivalent to a year of sunlight? [You may ignore efficiency factors, which should affect answers by much less than an order of magnitude. All numbers needed should be found from general Internet sources].

Without yet getting into the calculations for a solution, as far as I know it is still possible for the Earth to escape the expanding radius of the sun. I would prefer to think of the whole scenario as a moral economic problem if we are around by then (in terms of plans to evacuate any remaining population vs. plans to put more effort into a new habitable world).

Yes, it is possible for people to move. But we would have to leave a lot behind (most of the ecosystem, for one thing). Moving the planet to keep it habitable would be less disruptive. I am serious about this, although of course it is ludicrous to discuss the options for a race with many millions of years of development from now. The technological challenges should be achievable in centuries, but the implementation is another question altogether (and there is no hurry).

I am not so sure there is a need to do anything. There is nothing wrong in the human race dying. Think of the possibility of the change in behavior of humans before they die, for example. They often ammend their lives. To submit oneself to the natural progression of our solar system is to experience the laws of nature. A comforting fact.

Darwin would not be impressed! Or to put it another way, the branch of our ancestors that is more motivated to survive will do so.

That is quite likely true, I am just trying to say that the alternative is not so bad. Now I would send my family away if I could safely, and I would only go with them if I thought they would not be able to sustain themselves (probably).

The process I am describing would be extraordinarily slow, at a fraction of a degree per million years. The problem may be delayed quite a long time by biological adaptation, but it seems unlikely that we could evolve to could live at normal pressures above the boiling point of water, and it would be extremely difficult to preserve a functioning society by technology under such conditions. But even so, it would be an imperceptible change towards a world where our society would gradually fail to function over millions of generations.

This has got to be one of the most bizarre forum topics ever...

It's hard facts, Math_magician. Well, as long as the current understanding of the relevant areas of science are accurate enough - I believe they are fairly reliable.

Since everyone else seems too lazy to look up the numbers, I will give you my answers (efficiency factors make things mildly worse, by some single figure factor).

(1) The amount of energy from fusion of all of the hydrogen in the oceans is enough to accelerate the Earth to about 180 km/s from rest, compared to it's current orbital speed of about 30 km/s. At the moment there are not even long term plans for fusion of the main isotope of hydrogen, but deuterium is not abundant enough to do the job. Surely we can solve the technical problem of fusing protons in a few millenia, or even a few million years to be sure?

(2) The sunlight incident on the Earth provides a similar amount of energy over roughly 6 billion years (about 160 million years worth would be enough to accelerate the Earth to 30 km/s from rest).

So with adequate planning, either source of energy would be perfectly adequate, but fusion of a few percent of the oceans would allow it to be done in a more rapid time scale. The less than pressing nature of the end of life on Earth might make it difficult to get the political will to make the investment necessary to preserve the lives of our great^(many millions) - grand children. But heck, it may be easier to colonise worlds further out from Earth and let the population gradually shrink if necessary. Life on Earth will disappear with a whimper, not a bang, eventually.

[The efficiency issues may be tougher than I thought. It's about transferring momentum rather than energy, and to do this efficiently probably involves ejecting a sizeable fraction of the Earth's mass as propellent, as using a small amount of high temperature propellant is too inefficient in terms of energy to momentum ratio. Ejecting, say, 10% of the Earth's mass might be problematic].

why move the earth if our ancestors colonized, it?  Technology would find a way for us to travel through time, and thus relocate to another earth.  We just close the porthole, and live happily ever after.  Just as fruit, humans evolve on an earth.  This fruit, are called...adam and eve.  And that is the reason, why we differ in evolutionary age...we are from mars, or the astroid belt, that was once a planet... Time travel is the only logical way to travel to other worlds, and I believe it exist already.  Also that abraham lincoln and jfk, are one and the same person, sent back into time, to prevent catastrophe...evident is the amount of people alive today, and the expansion of knowledge...someone is changing  history, to save the future...

It is possible that history was "saved' to help the future, but what about all of the other disasters in history that weren't prevented? Perhaps a thing advanced enough to make that time travel would know what is most worth saving and what is not...but I would question their/its ethics if such a being existed.

I prefer asking an entirely different question that often occupies my thoughts: What is the value of "L" (Frank-Drake equation) that our universe wants for us?

matter are collected with anti-matter...what collect the knowledge of the universe...perhaps we are the sponges, that collects that. perhaps our purpose is to be creative...to shift paradigm, to feed our empty brains, with weird things.

Think of it this way...if we evolved...why did we evolve with a brain that can store information, that was unheard of? I mean, the first computers didnt come out with a 320GB drive, yet humans have this vast brain...to store what? perhaps we use 10% of it. So why don't we know how to use it.  All the other organs we use 100%

That we don't use all our brain is not a very solid fact. One could equally say we don't use all our muscles to their maximum capacity, because they are only used a fraction of the time, mostly at well below maximum power. I believe there are not actually any totally unused parts of the brain.

I have to agree with Elroch here, nearly 100% of our brain is being used throughout our whole waking day. Indeed I read an article suggesting that we have even more background work going on than what was previously ruled out from MRIs.