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For the longest time growing up with Peak Oil and other such dire predictions, I assumed humanity had just about peaked, in terms of industrial-technological might and capacity to influence its environment. So, just like most deadly diseases are self-limiting due to their virulence, so would we eventually flare out and extinguish ourselves.

Later, as I adopted more of an engineering, back-of-the envelope Fermi calculation approach to things, I began to change my view on that. I have come to think that there are enough nuclear, solar and potential fusion power sources here on Earth to last us for centuries. Out there, in space, there are truly cosmic amounts of resources lying about the solar system, just waiting to be plucked by our greedy little hands, unspoiled worlds waiting for our buldozers, and perhaps juiciest of all, the fount of energy that is the Sun, and virtually every Joule of it is wasted, when we could turn it into plastic toys and telenovelas. Like a cancer cell on a pure sugar diet, we can spread and spread and spread.

So this got me thinking. Is there an ACTUAL hard limit to growth? When would we hit the walls of the Petri dish?

From where I'm looking, you can't even see the walls. For instance, assuming 3% year-on-year growth (the high end of our past historical average), 1000 years linearly into the future, I would get a power output (or GDP, whatever you want to call it) that is 6 thousand billion times larger than today's. Sounds insanely high, right? That's about 1% of the yearly power output of our Sun. 1% of a single-star single-layer Dyson sphere... And there are a hundred billion stars, and a hundred billion galaxies. That's a lot of Agar-Agar to spread in.

So, is there a hard limit to growth, either here on Earth, or out there in Space? What is it? To make it more specific, you can if you wish restrict the scope of the question to 1000 years, but if you want to delve farther into the future, I'd love to hear it.

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  • $\begingroup$ Any answer will depend of the technological constraints, don't it? You mention a "1% of a [..] Dyson sphere" as if it was an easy thing to do. In the end, without space travel, there are some pretty quite hard limits in this planet. $\endgroup$ – SJuan76 Feb 16 '15 at 0:26
  • $\begingroup$ For the purpose of this question, do you consider that the universe is finite or infinite? $\endgroup$ – Vincent Feb 16 '15 at 1:57
  • $\begingroup$ @SJuan76, we've been at this science and industry thing for what, a couple of centuries? I'm talking 1000 years into the future. Hell, yes, we can damn well build 1% of a damned Dyson sphere in 1000 years. What else are we gonna do, twiddle our thumbs? $\endgroup$ – Serban Tanasa Feb 16 '15 at 3:56
  • $\begingroup$ @Vincent, your guess is as good as mine. As far as I know, regardless of it's size, there are areas outside our lightcone, so forever out of reach... $\endgroup$ – Serban Tanasa Feb 16 '15 at 3:57
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    $\begingroup$ I didn't think that your figure of 6 trillion could possibly be right, so I fed your growth parameters into an interest calculator, set the initial value a $1 and let it grow for 1000 years. 6.8 Trillion and change!!!!! Wow! Tomorrow morning I'm going to go open a bank account for my great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-great-grandkids! They'll be RICH!!! but if inflation continues at its current rate, it won't matter! $\endgroup$ – Henry Taylor Feb 16 '15 at 4:32
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When the center of the cancer cell can no longer get resources.

You have to be able to channel that growth to the fringes, which is going to leave the center a mess. We could abandon the center, and just wreck a wave of destruction outwards, which might work out okay. If we don't, expect those trapped at the center to start attacking those who're getting the resources. If you're starving, you will do what it takes to get fed.

Moving resources from the virgin sources back to the center, while the center keeps increasing its demands is tough. And having to go further away to get more resources becomes tougher.

We'll run out of easy to exploit virgin resources after awhile. We've done so on Earth, and the lessons we're learning now might be forgotten once we get to all that sugar awaiting us in space.

But, we're going to have a lot of fun with all that sugar... if we can get there before choking on our own [output].

But, eventually the stars run down. Also, they get further and further away from each other (expansion), when they supernova it's difficult to feed all those results back into new clouds to get new stars from... also, without getting blackholes. It also depends on what the actual physics of the Universe are... and we don't know that yet.

There's a lovely short story about this, "The Last Question"

If you want to limit things to 1K years, practically no limits exist - except our own incompetence. We could go to space today, if we were willing to fund it. If we did, humans won't fail as a species. If we don't, we could choke any number of ways, taking our life support down with us (ie: Earth as a human habitable world). We're likely in the process of doing that right now, heading to a new thermal maximum (like PETM). That's not to say we will, but it's significantly more dicey if we're not off the planet.

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  • $\begingroup$ Should be a fun couple of centuries, no? So glad to be alive to see it. $\endgroup$ – Serban Tanasa Feb 17 '15 at 14:19
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    $\begingroup$ We're probably not going to make it (unless you're like 10). The Singularity is proposed, but I don't think we're going to make it on time. And I don't think everyone is going to get the goodies - at least under the current system. The players at the top may knock the chess pieces off the board rather than lose control. I would love to be proven wrong however. I'd like to get my hands on so much sugar that I choke ;) $\endgroup$ – user3082 Feb 20 '15 at 7:56
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In any growth situation, a limit is one that would require a reduction in the growth rate (in this case 3%).

This limit occurs when the ability to collect the energy and resources needed to continue that growth is exceeded by the volume of that growth, i.e. when we can't accumulate energy and resources fast enough in comparison with our population.

Given that humans are intelligent and extelligent, this is not a simple matter of biology any more. We will reach the limit of our growth when our extelligence is unable to come up with ways to harvest sufficient energy and resources to continue that growth.

However, given the nature of extelligence, a reduction in the rate of growth may be temporary, as solutions allowing resumed growth may be subsequently discovered.

If it turns out that FTL travel in the form of some device such as an alcubierre-drive starship or traversable wormhole generation is practical, then the hard limit to growth would be the mass of the universe itself. Otherwise, the hard limit to growth would be the point at which we would have to expand faster than the speed of light to obtain the resources we needed to continue growth at the specified rate.

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    $\begingroup$ I read some funny sci-fi short story about FTL, and that alcubierre drive (which everyone is using) is causing the expansion of universe - consequences of FTL is the "dark energy". $\endgroup$ – Peter M. - stands for Monica Feb 16 '15 at 19:54
  • $\begingroup$ Peter, what's the name of that story? $\endgroup$ – user3082 Feb 17 '15 at 8:40
  • $\begingroup$ @PeterMasiar what is the name of that story? $\endgroup$ – Xandar The Zenon Mar 3 '16 at 4:18
  • $\begingroup$ I honestly do not remember but I will try to dig it out for you guys. It was just a short story (1-2 pages or so) which turns your world upside down, like They are made of meat $\endgroup$ – Peter M. - stands for Monica Mar 3 '16 at 15:05

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