Plenty of people are worried, Stan. The OP is a pretty feeble one; I've no idea what point Sandman wants to make or discussion he/she/it wants to start, so I'll interpret how I see fit...

The history of Homo Sapiens is, I think, one of energy thresholds. We wandered around hunting / gathering in family groups. Then some bright spark (pun intended) discovered that fire could change our food, could make more things more edible, and fire could do other things too, such as harden wooden points.

We mastered fire (to some degree); we learnt to make it when we wanted it & to use it when we had it. That's your first energy threshold.

Next, around 12,000 years ago, we started developing agriculture & domestication. Actually, domestication was likely something that had been ongoing for a long time, but it's difficult to pinpoint when it began. The point is that it now wasn't just what we could gather with our own muscle. Now, we are growing our food, not simply wandering around hoping to find some. We are raising our own animals, both as food and, importantly, as helpers. Dogs help us hunt, various herbivores help us as beasts of burden, sources of resources, etc.

We cross another energy threshold. With more food, more reliable food, available we grow in population. We start to form larger communities, because we can sustain them. We start to form more static communities because we don't have to keep moving around to find our own energy. We create an environment in which specialists can innovate & thrive. Who will become a smith or a carpenter when the first & only thing that matters is food in your belly? But if someone will supply you with food in exchange for what you can provide them with that they can't make...

If you look at it closely, this is an inarguable thing. The rate of change of technology is a parabolic curve. It is very slow to start with, almost flat. But one 'invention' leads to two, and two lead to four, and... The rate of change of technology is always on the up. Think how much the world has changed in the last 50 years compared with the last 500.

So, Homo Sapiens proceeds slowly after agriculture, from the first building blocks of civilisation. We do invent sails for our boats, windmills where there's enough wind, folk figure out how to make bronze, to smelt iron, and what we can do grows along with our population. But, essentially, we are still within the same energy threshold - what we can do with our own muscle & with the muscle of our domesticated animals. That's still all we have.

Then cometh coal, cometh the industrial revolution. We've known about coal for years, burnt it for years; hell, we even char wood to make a similar energy dense fuel known as charcoal. But we're still within the same threshold. And then some clever bugger figures out a way to release the energy from coal to work for us in a way that we & our animals cannot do. Some clever bugger invented the steam engine. Which needed & begat so much innovation... The Industrial Revolution is probably, so far, our biggest innovation and the biggest energy boundary we've crossed. Oil is no different to coal, essentially. Easier to manage, more versatile, more energy dense, but still. And nuclear fission - not what anyone hoped it would be & with difficult to manage consequences.

We are still very firmly in the the Industrial Revolution Age, in the fossil fuel age. Our next energy threshold is cracking fusion. Imagine that, if you can. Fusion is limitless energy with few, if any, consequences. That's what see & hope for, anyway. What will we do if we can master that? The sky is not the limit, only a beginning...