More green spaces linked to slower biological aging

Like others have said, this would make things so spread out as to be unusable for walking/biking. You want more density, but with large, nearby swaths of mixed use spaces with lots of greenspace and walking paths, biking paths, shops and activities, and public transit. The higher density supports the local shops in walking/biking distance, as opposed to suburbs where you drive to larger more central locations for shopping. This also means you need less space devoted to roadways and parking spaces, so you get even more space available for mixed use type greenspaces. You then have a city that is comprised of lively individual neighborhoods where people can go about their daily lives and activities within a half mile of green space filled walkable area, or they can hop on public transit (or ride bikes on protected paths) to go to one of the other lively individual neighborhoods.

Why does low population density guarantee a failure (failure of what)?

About Le Corbusier. His core idea is interesting but from what I've seen the "towers in a park" implementations are basically "massive ugly badly designed towers surrounded by a malnourished slivers of grass". Also, for those: 1. the population density is invariably way too high, 2. the towers are always massive, 3. the green space sizes are absolutely too small, 4. the "green spaces" are boring and/or half dead, many times only grass (why not have gardens that actually produce food for people who live there, or forests)?

For example, Stuyvesant Town is one "tower in the park". It is IMO too crowded with too high towers. Reduce number of towers to 4 or 5, make towers lower, and it'd be more like it.

To give an exaggerated example, if one were to put a 6 floor tower right in the middle of Central Park, that's what I'm kind of after...

Why does having a car reduce the population density or impact foot/bike/bus at all?

As for the density cutoff of 2000 people / square km. Here we'd have a building of 100 people, 40 apartments (assume family of 2.5 people), 5 apartments/floor, 8 floors. Tower footprint won't make a huge difference, let's say it's > 500 m2, and this would be 1..2% per tower total area. In 1 square km (100 hectares) we'd have 20 such towers á 100 persons, thus 2000 people per square km. The towers would be quite low, and this would still be "dense enough" per that cutoff.

(This is napkin math so the real number is slightly lower or higher depending on various parameters)

Anyway, this an idea I'd like to see happen. I'm not an architect/planner (perhaps for a reason, say the shouts from the audience).

PS. https://www.sweco.se/projekt/satra/ this project (in Sweden) aims to build greenspaces where inhabitants can produce food. That's the theory at least, it will be interesting to see how it turns out. I do think this is again way too dense, but greenspaces to produce food is a great idea.

Not at all. That's not how science works. A huge percentage of rigorous scientific studies are specifically showing correlations between things.

"Correlation doesn't equal causation!" cried the internerds.

It doesn't need to. If you've got a set (P) of N people who consume substance X, and N people (Q) who did not consume substance X, and 100% of set P died within half an hour of that act, and 100% of Q are still happy little dandelions, that is an entirely valid scientific finding, and an entirely sufficient reason to stop the supply of substance X.

But there is a whole spectrum between the densities of super low-density rural Tennessee and hyperdense NYC-like places and I find the ideas for something in-between are largely unexplored in practise because of various reasons.

The argument of closeness of amenities prioritizes a consumption-based lifestyle over building good nests for humans (and little humans) to actually live in. Let's take your example, where you said people don't like to walk 1 km to a small convenience store -- is the assumption somehow that walking 1 km to reach the tiniest park is something people would like?

As for jobs, I'd say very, very few people live in a city next to their jobs. They have to commute in one way or another. This seems to fall mostly between 10 minutes to 60 minutes when discussing with people. Time-wise I'd say this range is aligned with a smaller town/city (either a job in the town/city, or in another town/city).

And speaking of enjoyment, to be honest I'm not convinced many people in big cities really enjoy it. I'd wager to say that most people generally would enjoy a less noisy and overall cleaner environment where nature is nearer than concrete. Not everyone, but most.

My childhood town (in Northern Europe) is 31 people/km2. It's overall about 80 k people (lots of empty space). Density-wise it's probably something like your rural Georgia but everything one needs is there, plenty of shops and businesses of all kinds and even some variety in restaurants (believe it or not). Quite many people could actually do with a bicycle or a bus, but in practise people have a car because of winters and four seasons and because buses don't run all the time and reach everywhere. So then, for example, most people do groceries once a week and drive that 3-10 km to the grocery store or mall concentrations. But based on my experience, they would likely do exactly the same thing in a bigger city too, since the inner-city core grocery stores are more expensive with less variety.

Also, there's a spectrum between bare grass or wild forest... For example, where I live now one might have a "wild" forest designated as a "park", and someone from the municipality just cuts away the hanging branches, windsnaps and such and ensures the paths don't grow shut. It's very low effort and cost. Once in like 5-15 years they might cut some more growth of trees so there's more sunlight everywhere. This type of "park" does not have manicured golf course like grass areas and fountains and so the per year per area cost are much smaller.

So it's not about the cake and eating it, it's about having a different kind of cake.

Anyway, thanks a lot for the link!

Edit: PS. I followed your link now; the concept of Neighbourhood Park is a neat one. That is kind of what I mean, more of that, not necessarily with golf course lawn. Also, the "John F. Collins Park in Philadelphia" looks great!