3 Things Economics Can’t Solve

Question: What is the relationship between economic growth and life expectancy?

Kate Pickett: What we find is, in the rich developed market democracies, there’s no longer any relationship between average levels of income in a country and life expectancy. So, you can have a country like the USA, or Norway, that’s twice a rich as another country like Greece for instance, and that doesn’t seem to affect life expectancy at all. And the same is true of happiness. Happiness isn’t related to average levels of income in a country either. Now, that’s not true of the developing world when you don’t have enough, when people are lacking food or shelter, or the basic material necessities. Then economic growth is really important. But in our rich, developed democracies, it no longer makes any difference. So, we seem to have come to an end of what economic growth can do for us in terms of life expectancy, happiness, well-being and that sort of thing.

If you look at the United States, over the past few decades, you’ve become twice, three times a rich as you used to be, levels of happiness haven’t improved at all.

Question: How does social inequality affect our health?

Kate Pickett: I think this is where it helps that Richard Wilkinson, my co-author and I, we’re epidemiologists, and so we study levels of population health. And one thing we really learned over the past 30 years in epidemiology is the importance of psycho-social factors for health. Things like low social status, or social affiliation, social networks, whether or not you have friends, and the stresses of early childhood. All of those things have turned out to be really important for health. And we have quite a good understanding now of the biology of chronic stress. So, all of these things are working as stresses, low social status, lack of friends or social networks, stress in early childhood. And chronic stress affects our biology, our physiology in lots of different ways. It affects our immune system, our hormonal responses, it affects our cardiovascular health. And that’s quite well understood. And so we have also known for a long time that the people at the bottom of society, the poorer people in our societies, people living in the most deprived neighborhoods have much higher levels of stress and much worse health than those who are more affluent or have higher social status.

Question: Is there a threshold for when economic growth stops affecting life expectancy?

Kate Pickett: Yeah, it’s not so much about the threshold, the threshold changes over time. It’s really just seeing that although life expectancy continues to improve over time, that’s not related to average levels of income anymore in the rich countries. Instead, what we find is really important is the level of income and equality that is the gap between the rich and the poor. That’s what seems to matter these days for our health and social well being.

An epidemiologist explains the evidence that life expectancy, happiness, and well-being do not increase with income and national wealth.

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The theory could resolve some unanswered questions.

Image source: NASA/Big Think
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  • Most stars begin in binary systems, why not ours?
  • Puzzles posed by the Oort cloud and the possibility of Planet 9 may be solved by a new theory of our sun's lost companion.
  • The sun and its partner would have become separated long, long ago.

If most stars form in binary pairs, what about our Sun? A new paper presents a model supporting the theory that the Sun may have started out as one member of a temporary binary system. There's a certain elegance to the idea — if it's true, this origin story could resolve some vexing solar-system puzzles, among them the genesis of the Oort Cloud, and the presence of massive captured objects like a Planet Nine.

The paper is published in Astrophysical Journal Letters.

The Oort cloud

Oort Cloud graphic

Image source: NASA

Scientist believe that surrounding the generally flat solar system is a spherical shell comprised of more than a trillion icy objects more than a mile wide. This is the Oort cloud, and it's likely the source of our solar system's long-term comets — objects that take 200 years or more to orbit the Sun. Inside that shell and surrounding the planets is the Kuiper Belt, a flat disk of scattered objects considered the source of shorter-term comets.

Long-term comets come at us from all directions and astronomers at first suspected their origins to be random. However, it turns out their likely trajectories lead back to a shared aphelion between 2,000 astronomical units (AU) from the Sun to about 100,000 AU, with their different points of origin revealing the shell shape of the Oort cloud along that common aphelion. (An astronomical unit is the distance from the Sun to the Earth.)

No object in the Oort cloud has been directly observed, though Voyager 1 and 2, New Horizons, and Pioneer 10 and 11 are all en route. (The cloud is so far away that all five of the craft will be dead by the time they get there.) To derive a clearer view of the Oort cloud absent actually imagery, scientists utilize computer models based on planetary orbits, solar-system formation simulations, and comet trajectories.

It's generally assumed that the Oort cloud is comprised of debris from the formation of the solar system and neighboring systems, stuff from other systems that we somehow captured. However, says paper co-author Amir Siraj of Harvard, "previous models have had difficulty producing the expected ratio between scattered disk objects and outer Oort cloud objects." As an answer to that, he says, "the binary capture model offers significant improvement and refinement, which is seemingly obvious in retrospect: most sun-like stars are born with binary companions."

"Binary systems are far more efficient at capturing objects than are single stars," co-author Ari Loeb, also of Harvard, explains. "If the Oort cloud formed as [indirectly] observed, it would imply that the sun did in fact have a companion of similar mass that was lost before the sun left its birth cluster."

Working out the source of the objects in the Oort cloud is more than just an interesting astronomical riddle, says Siraj. "Objects in the outer Oort Cloud may have played important roles in Earth's history, such as possibly delivering water to Earth and causing the extinction of the dinosaurs. Understanding their origins is important."

Planet 9

rendering of a planet in space

Image source: Caltech/R. Hurt (IPAC)/NASA

The gravitational pull resulting from a binary companion to the Sun may also help explain another intriguing phenomenon: the warping of orbital paths either by something big beyond Pluto — a Planet 9, perhaps — or smaller trans-Neptunian objects closer in, at the outer edges of the Kuiper Belt.

"The puzzle is not only regarding the Oort clouds, but also extreme trans-Neptunian objects, like the potential Planet Nine," Loeb says. "It is unclear where they came from, and our new model predicts that there should be more objects with a similar orbital orientation to [a] Planet Nine."

The authors are looking forward to the upcoming Vera C. Rubin Observatory (VRO) , a Large Synoptic Survey Telescope expected to capture its first light from the cosmos in 2021. It's expected that the VRO will definitively confirm or dismiss the existence of Planet 9. Siraj says, "If the VRO verifies the existence of Planet Nine, and a captured origin, and also finds a population of similarly captured dwarf planets, then the binary model will be favored over the lone stellar history that has been long-assumed."

Missing in action

Lord and Siraj consider it unsurprising that we see no clear sign of the Sun's former companion at this point. Says Loeb, "Passing stars in the birth cluster would have removed the companion from the sun through their gravitational influence. He adds that, "Before the loss of the binary, however, the solar system already would have captured its outer envelope of objects, namely the Oort cloud and the Planet Nine population."

So, where'd it go? Siraj answers, "The sun's long-lost companion could now be anywhere in the Milky Way."

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