Kepler’s forgotten ideas about symmetry help explain spiral galaxies without the need for dark matter – new research

August 8, 2019, by Chris Jeynes,Senior researcher, University of Surrey and Michael Parker  Visiting Fellow, University of Essex 

 https://theconversation.com/keplers-forgotten-ideas-about-symmetry-help-explain-spiral-galaxies-without-the-need-for-dark-matter-new-research-121017

 M81 spiral galaxy. NASA/JPL-Caltech/ESA/Harvard-Smithsonian CfA

The 17th-century astronomer Johannes Kepler was the first to muse about the structure of snowflakes. Why are they so symmetrical? How does one side know how long the opposite side has grown? Kepler thought it was all down to what we would now call a “morphogenic field” – that things want to have the form they have. Science has since discounted this idea. But the question of why snowflakes and similar structures are so symmetrical is nevertheless not entirely understood.

Modern science shows just how fundamental the question is: look at all the spiral galaxies out there. They can be half a million light years across, but they still preserve their symmetry. How? In our new study, published in Scientific Reports, we present an explanation.

 Real snowflake. Karen Schanely: https://www.clickinmoms.com/blog/take-macro-snowflakes-pictures/; public domain
 
We have shown that information and “entropy” – a measure of the disorder of a system – are linked together (“info-entropy”) in a way exactly analogous to electric and magnetic fields (“electromagnetism”). Electric currents produce magnetic fields, while changing magnetic fields produce electric currents. Information and entropy influence each other in the same way.

Entropy is a fundamental concept in physics. For example, because entropy can never decrease (disorder always increases) you can turn an egg into scrambled eggs but not the other way around. If you move information around you must also increase entropy – a phone call has an entropy cost.

Light wave with electric (E) and magnetic (B) fields. Author provided 

 

We showed that entropy and information can be treated as a field and that they are related to geometry. Think of the two strands of the DNA double helix winding around each other. Light waves have the same structure, where the two strands are the electric and magnetic fields. We showed mathematically that the relationship between information and entropy can be visualised using just the same geometry.
We wanted to see if our theory could predict things in the real world, and decided to try and calculate how much energy you’d need to convert one form of DNA to another. DNA is after all a spiral and a form of information.

Two forms of DNA. Parker & Jeynes, Fig.1 of Scientific Reports 9|10779 (2019); Modified from Fig. 5 of Allemand et al. Proc. Natl. Acad. Sci. USA 95, 14152–14157 (1998), CC BY 

 

This was actually done in extraordinarily precise measurements some 16 years ago. The researchers pulled a DNA molecule straight (DNA likes to curl up), and twisted it 4,800 turns while holding the ends with optical tweezers. The DNA flipped from one form to another, as in the picture above. The researchers could then calculate the energy difference between the two forms.

But our theory could calculate this energy difference, too. We knew the entropy of each of the two versions of this DNA molecule, and the energy is simply the product of entropy and temperature. Our result was spot on – the theory seemed to hold up.

From tiny to enormous

Spiral galaxies are double spirals just as DNA is a double helix – mathematically speaking they have similar geometries.
 

 

A spiral galaxy with an overlaid double-armed logarithmic spiral. Parker & Jeynes, Fig.2 of Scientific Reports 9|10779 (2019), CC BY-SA

 

Our theory shows directly why the two arms of the spiral galaxies are symmetrical – it’s because info-entropy fields give rise to forces (like other fields). The stars in the galaxy are simply choreographed by an entropic force to line up into a pair of such spirals to maximise entropy.

Continued at site ...

 

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