Tree of Souls - An Avatar Community Forum - View Single Post - Human Technology: Year 2154
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Old 05-08-2011, 07:14 PM
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Originally Posted by txen View Post
Tropical polar regions are a stable configuration. The fossil record seems to indicate that there were dinosaurs at 70 and perhaps more degrees of latitude.
During what times was this so and does it account for continental plate movement?
I know that there were times this was so, but at least in the last period it was like that, (IIRC that was about 50 Mya) the problem that arose was that the ocean currents stopped working as they do now, resulting in severe problems with marine life, eventually leading to a mass extinction. The worst mass extinction (before the dinos took hold) also was likely caused by global warming and lack of ocean circulation. What happens is the same as happens in stagnant lakes - you get a layer of anoxia near the bottom that can rise. You get H2S buildup that can be toxic. A tropical arctic would certainly not really be a good idea, I'm afraid. At least not unless and until there would be a biosphere evolving that somehow deals with that properly. This is not scientifically proven yet, but there is quite some evidence that such a world has and would be very harmful for many species, including humans and especially the food species they depend on.

While the carbon dioxide forcing that humans are applying to the climate will have at least some effect, it's the secondary effects that will make for the big changes.
Indeed - it is the positive feedback mechanisms that accelerate changes and multiply the impact.

I'm thinking that there is a lot of underestimation of the dust density. We really don't know what the interstellar dust density is.
That is what I also think. Maybe it is really low, but the only way we know anything about that is from Earth based observations and modelling approaches. There is some uncertainty though in respect to those, a lot of space is still unknown (e.g. the famous "dark matter and dark energy" problem). Anyways, I think there is not enough evidence to know if interstellar space is really just a void with no dust to speak of.

The issue of radiation is also very valid. It is already a problem inside the solar system.

Oh and an interestin part would also be - if the acceleration period is really only a fraction of the journey (0.5 years each), would that not mean that most of the acceleration happens inside the solar systems, meaning one would have to deal with all the dust in there?

Originally Posted by Human No More View Post
That's the definition of homeostasis - it fluctuates above and below a certain level
Yes, that is true, but the average level is also not stable. It can shift or rather jump. That all tropical world or tropical arctic scenarios may even be stable in themselves, but the average level is at a different place, so how would people deal with that.
If climate change is pushed beyond a tipping point, the new homeaostasis level may be different than now.

Of course, human activity changes the equilibrium level, but if it is within the capacity of the ecosystem then not so much changes.
Yes, but I think as many climate scientists do, that we are on the way of reaching tipping points and breaching that capacity - or are already beyond the capacity. We definitely are beyond the carrying capacity right now, the amount of degradation rises and it is questionable at what point the system cannot relapse anymore. That is what I also meant with resilience - if a system is resilient, it can return to the average level again. But if they are stretched too much, it wont work. And we are currently not only putting a strain on the parameters like CO2 and Methane but also diminish resilience by eliminating species and ecosystems with other means.

Of course, some evidence for that is required...
Well, it is of course based on modelling, but up to now, the reality usually exceeded the projections - so in away yes - your claim that interstellar space poses no risk in terms of particles and radiation to a spaceship is as based on my claims that climate change will be severe on hypothesis, some evidence and mathemathical and theoretical projections. Only the future will tell.

It isn't about impact, it was about plausibility. I know your particular single interest and how you like to talk about it with every single marginally related topic you can find, but this isn't about current day Earth. It is possible, especially with the degree of industrialisation seen. ...Nobody ever said it took 'a couple of years'
Ok, so lets skip that part mostly to not drag this into my presumed "single interest". But my point is that to develop industrialization more, to reach&maintain a population of 13 billion, to create spaceships, you need a working economy, you need food security, you need energy and you need working ecologies on this planet. Even in a mechanistic view that only looks at how humans can succeed and that does not care in an emotional way for nonhumans there is something we in ecology call "ecosystem services". This ranges from simple things like providing clean water, food, oxygen to more complex ones like a stable climate, protection from toxins or radiation. Right now, we all depend completely on these ecosystem services. Only a few people in the world have the need and can provide the energy to use distilled or deionized water, grow food completely under artificial light or can evade toxins that are in the air by filtration. No one yet can live without healthy ecosystems. Maybe it is really possible to live without them in a sort of "biosphere 2" or even in a purely technological spaceship-type environment. But my argument is that this is not feasible for 13 billion people to do it that way and that it would take quite a few drastic and fast changes and new technologies to somehow keep humanity going without a working ecology on this planet. But as I said, we can skip this discussion in this context, if the intention of the thread is to examine what technologies would be possible and feasible in the "best case scenario".

I have to admit, I am a bit surprised that there seem to be quite a few technologies that already go into the direction as seen in Avatar. I was unaware that space travel to Alpha Centauri would actually be possible in less than 6 years if one can somehow maintain a 1G acceleration.

...I posted the information
There is a shield that is intended to protect against any dust that can theoretically be encountered ...
The shield is in multiple layers...
It's in effect a scaled up Whipple shield...
Ok, thank you for the last link, because my question was not if the shield has layers or that there is a shield that does its job, but I was asking about the technology itself. The Whipple Shield seems to be a shield made of some material like Kevlar that physically absorbs the impact of particles. If this really works on scale and at 0.7c and against single particles I do not know. I am an ecologist, geobiologist and not a space engineer
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