Conscious Choice cover

From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.

Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.  
Conscious Choice does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.


“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.


Available everywhere for $3.99 (before discount) at Amazon, Barnes & Noble, and all ebook vendors, or direct from the ebook publisher, ebookit. And if you buy it from ebookit you don't support the big tech companies and I get a bigger cut much sooner.

Astronomers discover white dwarf stars still burning hydrogen

The uncertainty of science: Using Hubble observations of the white dwarfs in two different globular clusters, astronomers have discovered that — contrary to the consensus opinion — some white dwarf stars are not slowly cooling embers of a dead star, but are still generating nuclear fusion by burning hydrogen in their outer layers.

Using Hubble’s Wide Field Camera 3 the team observed [globular clusters] M3 and M13 at near-ultraviolet wavelengths, allowing them to compare more than 700 white dwarfs in the two clusters. They found that M3 contains standard white dwarfs, which are simply cooling stellar cores. M13, on the other hand, contains two populations of white dwarfs: standard white dwarfs and those which have managed to hold on to an outer envelope of hydrogen, allowing them to burn for longer and hence cool more slowly.

Comparing their results with computer simulations of stellar evolution in M13, the researchers were able to show that roughly 70% of the white dwarfs in M13 are burning hydrogen on their surfaces, slowing down the rate at which they are cooling.

This discovery could have consequences for how astronomers measure the ages of stars in the Milky Way galaxy. The evolution of white dwarfs has previously been modeled as a predictable cooling process. This relatively straightforward relationship between age and temperature has led astronomers to use the white dwarf cooling rate as a natural clock to determine the ages of star clusters, particularly globular and open clusters. However, white dwarfs burning hydrogen could cause these age estimates to be inaccurate by as much as 1 billion years.

In other words, many past age estimates for star clusters could be very wrong, which in turn could mean the general understanding of the evolution of these objects could be very wrong as well.

These results also illustrate a fact that astronomers seem to always forget. The stars in any one category (white dwarfs, red super giants, yellow stars like the Sun, etc.) are not all identical, and thus their life and death processes will not all follow the predicted stages, like clockwork. Things are always far more complicated. Though the predictions might be broadly right, there will be many variations, so many that it will often be difficult to draw a generalized conclusion.

It seems that with white dwarfs astronomers have made this mistake, and now must rethink many of their conclusions.


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  • John

    I thought fusion was possible due to the tremendous temperature and pressure at the core of a star. Burning hydrogen on the surface doesn’t seem to make any sense.

    Also, the age estimates are only off by a billion years. Billion smillion.

  • John: Burning hydrogen on the surface of a white dwarf makes sense because the star is so dense already. Remember, this is only one step up from a neutron star or pulsar. A lot of mass is packed into a small space, so that if there is leftover hydrogen on the surface it could be under enough pressure and temperature to fuse.

  • Ryan Lawson

    Yeah, I suppose the density of the stellar core that is the white dwarf has enough gravity at the surface to generate sufficient pressure in a layer of hydrogen for a smoldering fusion. There’s a fairly simple equation for determining surface gravity that can be done back of the envelope to check (but I forget off the top of my head and haven’t used it in 20 years).

  • From the Wikipedia article on surface gravity:

    “The surface gravity of a white dwarf is very high, and of a neutron star even higher. A white dwarf’s surface gravity is around 100,000g (9.84 ×105 m/s²)”

    Yeah, that’ll do it.

  • pzatchok

    Well as they say. All things are possible…….

    Those white dwarfs could have pulled mater off of a companion or are passing through an area of dense stellar hydrogen.
    Or they could still have a little left over from before they collapsed.

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