Habitable Planets Just Got Much More Rare
If this scientist’s theory about the origin of magnetic fields is correct, habitable planets will be few and far between.
Earth has a magnetic field sufficient to support life. Venus does not. Why does “Earth’s twin” lack this protective shield?
According to secular geophysicists, a magnetic field is generated by a dynamo in a planet’s interior. The dynamo is generated by convection of molten material in the planet’s mantle. (Whether this theory is defensible is dealt with in chapter 7 of Spacecraft Earth: A Guide for Passengers.) Granting, for the sake of argument, that the theory is adequate to explain Earth’s magnetic field, a problem arises: as a planet cools, its innards should become stratified. A layered structure, however, is not conducive to convection. Without convection, no magnetic field. Without a magnetic field, no life. At Universe Today, Matt Williams explains the conundrum:
Recent studies on high-pressure mineral physics and on orbital dynamics have also indicated that planetary cores develop a stratified structure as they accrete. The reason for this has to do with how a higher abundance of light elements are incorporated in with liquid metal during the process, which would then sink to form the core of the planet as temperatures and pressure increased.
Such a stratified core would be incapable of convection, which is believed to be what allows for Earth’s magnetic field.
Williams points to a new study by Seth A. Jacobson of Northwestern University and colleagues from Europe. To get convection started on the Earth, they surmise, the alleged Moon-forming impact stirred the mantle and core sufficiently to instigate convection.
The significance of this study, in terms of how it relates to the evolution of Earth and the emergence of life, cannot be understated. If Earth’s magnetosphere is the result of a late energetic impact, then such impacts could very well be the difference between our planet being habitable or being either too cold and arid (like Mars) or too hot and hellish (like Venus).
It also means that exoplanets around other stars will be unlikely to have habitable planets.
Looking beyond our Solar System, this paper also has implications in the study of extra-solar planets. Here too, the difference between a planet being habitable or not may come down to high-energy impacts being a part of the system’s early history. In the future, when studying extra-solar planets and looking for signs of habitability, scientists may very well be forced to ask one simple question: “Was it hit hard enough?”
Not just any impact will do. Jacobson’s open-access paper at Earth and Planetary Science Letters says, “Late, giant impacts may mechanically mix the core, removing the stratigraphy.” Many planets show scars of numerous impacts, but according to current secular thinking, the Earth took a wallop huge enough to send enough debris out to form the Moon. How often does that happen? And how long can the stirring last while life is trying to get a foothold? (in evolutionary thinking, that is).
Fans of Spike Psarris’s DVD on the solar system will recognize the materialists’ all-purpose explanatory tool at work here (sound the bugles! another impact!). Even secular critics may see the impact requirement as a new epicycle to maintain a consensus theory that already suffered defects, such as maintaining the field for millions of years. Measurements show Earth’s field has decayed at 5% since Carl Friedrich Gauss measured it in 1835. Dr Richter explains the significance of this decline:
Let me tell you, a decrease of 5% in the earth’s magnetic field strength represents a huge energy change. The earth’s magnetic field stores an immense amount of energy. To have this amount decrease by 5% in a little over 100 years represents an enormous loss of energy in a relatively short period of time. Calculations on this rate show that the field’s half-life is 1400 years; in other words, in 1400 years the field strength will be half what it was. Some day in the future—should the earth remain and the decay continue—the magnetic field will effectively vanish.
The dynamo theory, Richter explains in chapter 7 of Spacecraft Earth, fails to account for this empirically observed decline, and argues against millions of years (note that the decay concerns the strength of the field, not its polarity). If Richter is correct, the Earth would have been uninhabitable a few thousand years ago (because the field would be too strong), and will become uninhabitable within a few more thousand years. For the sam reason, exoplanets would also have a brief window of habitability that would be far too short for Darwinian evolution.
Such problems are rarely considered in confident-sounding news articles. For example, Fox News states, “‘Super Earth’ is discovered and it has perfect conditions for aliens.” There’s no mention of a magnetic field at all. Also ignored is that this ‘super Earth’ orbits a red dwarf, which makes it a poor candidate for habitability.
Red dwarfs are the most common type of star, reports Phys.org. But they are also the most deadly. In the article, John Greenwald says, “Blowing in the stellar wind: Scientists reduce the chances of life on exoplanets in so-called habitable zones.” Strong stellar winds tend to sweep away the atmospheres of planets orbiting red dwarfs. They are also subject to emit deadly flares that would quickly sterilize a planetary surface.