The thing that really is set in opposition to this idea is that we will eventually live off planet. But for the sake of discussion we could say we are living in a finite world. i.e. a world with limitations.

"What will happen to the economy when the Earth runs out of resources?"

The easiest solution to this is to make everything regenerative and all materials used recyclable. If this is done even to the smallest degree it will allay the problems of "running out of resources." Meaning, we won't be running out of cows or plastic any time soon.

Oil on the other hand is a great example of a resource that could be depleted, but if we apply the first rule as stated here, than we should be able to utilize other forms of energy to give us the mobility we so require.

"Is depression inevitable?"

Not sure, but I would say that there are factors that bring it about. In an unstable economy recession and inflation are a double edge sword. Finding solace in the middle is most desirable, and should be on the mind of the main regulators of the economy, i.e. the banks and the federal government, daresay the 1%.

Economic growth isn't just about "material resources."

And as mentioned above, even with material resources, there's a belief that we'll be able to utilize extraterrestrial resources before very long. We already do to some extent with solar power, for example.

But the potential infinity of economic growth is about the potential infinity of time, the continued "evolution" of creative ways to produce wanted goods and services, creative/more ingenius ways to capitalize on material resources (including things like nuclear power, for example), and the prospect of harvesting resources elsewhere in the universe.

There ought to be a name for such arguments - 'hasty materialisation', or something.
What has infinite growth potential is human desire. 'The economy' is not a pile of stuff that is running out, indeed very little that was on the planet has left it. On the contrary, limitation of resources increases their value. If gold was as common as sand, it would have negligible value, so the economy grows as resources shrink. Most of the economy of today is accounted for by things that had no existence at all 100 years ago; they have novelty value, rather than survival value.

"Anyone who thinks that you can have infinite growth in a finite environment is either a madman or an economist." -- David Attenborough.

Economists are concerned with growth. They want to know how much the economy is growing. If the economy slows down significantly, we call it a recession. Presumably the more the economy grows each year, the better. But the earth has finite resources, and can't grow indefinitely. So, what's going to happen to the economy when the earth runs out of resources? How is it possible to have more growth? Aren't we destined for a great depression that we can't recover from? Perhaps we need to reconsider our notions that a growth hungry economy is necessary, and accept the possibility of a steady state economy.

Do you believe in the crazy idea that we can have infinite growth on a finite planet? — Purple Pond

I believe we can achieve sustainability without significantly altering the economic model. The changes that are required are philosophical and political. Our mistake is about 400 years old, and concerns Galileo - and the presentation of his thesis 'Dialogue Concerning the Two Chief World Systems' (1633) to the Church. He was arrested and tried for heresy - because his findings contradicted Biblical orthodoxy. His work, which contained the first formal presentation of scientific method - was prohibited, and this had a chilling effect on all subsequent philosophy and scientific endeavor.

In effect, science was branded heretical - even as it was employed to power the industrial revolution from 1730. It proved a useful tool, but as an understanding of reality - science remained "grievously suspect of heresy." So religious and political ideology - particularly the Divine Rights of Kings the basis of the sovereign nation state in the Treaty of Westphalia (1650) was maintained, and technology was applied for the ideologically conceived good - as opposed to the scientifically conceived good.

Correcting that mistake is difficult, and requires of us a little sophistication. We need to protect ideologically ordered society, while at the same time - recognizing the significance of scientific truth, and applying technology accordingly. I believe that's possible - and furthermore, that in that context - capitalism is sustainable. Not merely because there are vast untapped resources on earth - and an infinite supply beyond, but because applied correctly, technology multiplies resources.

Foregoing the miracle of 'the invisible hand' at the heart of capitalism would be a foolish mistake. Foregoing the personal and political freedom for which capitalism provides would be criminal. It's not capitalism that's the problem - but rather the religious and political context within which it operates. Directed in the course of scientific truth - capitalism can easily achieve sustainability.

What do economists learn about ecology and natural sciences in university? Is anybody in the thread an economist? What do you really know about these things. In Spain courses tend to include subjects that are relevant for the degree, for example to become a language teacher in Primary you also need to have a good knowledge of sociology, psychology or even certain areas of mathematics. This is so because you have to work personally with experts in those fields, and also to inform your teaching practice. Do economists study ecology?