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January 2024

Evolution, Environment, Chromosomes, and Galaxies

By Bob Snodgrass
Posted: 01/10/2022

Summary of last meeting

Pasadena Village Science Monday, summary of Dec 13th meeting

Next meeting Jan 10th at 4 PM.

 

This was a nice meeting with a good turnout. I was suffering from severe back pain and apologize for errors and omissions in my summary. Anything important can be dealt with in a corrigendum. I commented before the meeting began about the great importance of the James Webb Space Telescope and how many people would be biting their nails on the launch date (Dec 22 according to most NASA communications). It launched in fact on Dec 25th without complication.

Barbara had sent around two excellent papers about scientific findings held to be valid and important until toppled by later better investigations. I asked her to go first but she wasn’t ready so Howard went first and spoke of examples of climate change apparently altering the pace of evolution, particularly bird beaks getting longer.

 

Barbara then presented her two noteworthy papers, which she sent around to everybody. First came the chromosome story. Doctor Painter of the University of Texas was a well known investigator. He produced several papers in the 1920s announcing that humans had 48 chromosomes. Not every researcher agreed, but many researchers agreed and Painter’s ‘discovery’ was incorporated into textbooks. Then after WW II in the great scientific renaissance with new techniques such as so-called squash preparations new findings turned up. The most important were in Sweden at Lund University. Their first photograph in 1956 is shown below and was soon confirmed by workers at the Harwell MRC Research Lab.

Graphical user interface

Description automatically generated with medium confidence

 

This did not end the controversy. Some workers clung to the textbook standard. But in 1959, Lejeune and Gautier reported that patients with Down syndrome had 47 chromosomes due to an extra copy of chromosome 21, This convinced everyone, including my teachers,

 

Likewise the famous studies of Miller and Urey in 1952 which simulated the conditions of early Earth by sealing water, methane, ammonia and hydrogen in a glass flask for days had great impact. Then they applied electrical sparks to the mixture. Miraculously, amino acids came into existence amid the hot mixture. It was a big deal, but much later others showed the borosilicate glass dissolved under the alkaline conditions used and react with the other materials. Glass containers produced many organic materials, but only a few were found with Teflon containers.

 

I learned about the Painter and Miller-Urey work in college, in the 50s.They were not fake science or false science but they were superceded by better work later. Sally A talked about the important Webb telescope on which her daughter did much work. Sharon brought up the issue of substitution for venepuncture- methods to analyze the blood without drawing blood, Many of the proposed methods analyze the breath, meaning that they don’t provide information about the formed elements of the blood (red cells, white cellss and platelets, Some other elements such as sodium and other minerals aren’t found in the breath, so for now, a survey of body fluids requires drawing some blood. We had more discussion on this topic.

 

Bob continued his astrophysical focus with a report of a small galaxy that appears to contain no dark matter at all. This directly contradicts present they which holds that dark matter holds the galaxies together. For example, astrophysicists have observed that Dark Matter played a vital role in the formation of galaxies and is responsible for keeping them gravitationally bound. However, when an international team of astronomers observed the ultra-diffuse galaxy AGC 114905, they found no evidence of Dark Matter at all. If these observations are accurate, this discovery could force scientists to reevaluate their cosmological models and the way we look at the Universe.

This story began when Pavel Mancera Piña – a Ph.D. student with the University of Groningen and ASTRON– and his colleagues observed six galaxies that appeared to have little or no dark matter. Posted on December 10, 2021 by Matt Williams

Galaxies Have Been Found With no Dark Matter at all

One of the greatest cosmological mysteries facing astrophysicists today is Dark Matter. Since the 1960s, scientists have postulated that this invisible mass accounts for most of the matter in the Universe. While there are still many unresolved questions about it – i.e., What is it composed of? How do we detect it? What evidence is there beyond indirect detection? – we have managed to learn a few things about it over time.

For example, astrophysicists have observed that Dark Matter played a vital role in the formation of galaxies and is responsible for keeping them gravitationally bound. However, when an international team of astronomers observed the ultra-diffuse galaxy AGC 114905, they found no evidence of Dark Matter at all. If these observations are accurate, this discovery could force scientists to reevaluate their cosmological models and the way we look at the Universe.

The research team was led by researchers from the Kapteyn Astronomical Institute at the University of Groningen and the Netherlands Institute for Radio Astronomy (ASTRON). They were joined by astronomers and cosmologists from the University of Durham, Valparaiso University, and the University of Illinois. Their research findings were accepted for publication and will appear in the Monthly Notices of the Royal Astronomical Society.

As the team explained in a previous study, the road to this discovery began when Pavel Mancera Piña – a Ph.D. student with the University of Groningen and ASTRON and the lead author on both papers – and his colleagues observed six galaxies that appeared to have little or no dark matter. These findings contradicted prevailing theories about dark matter, which states that all galaxies (especially ultra-diffuse dwarf galaxies) could not exist without dark matter to hold them together.

Piña and his colleagues were instructed to retake their measurements and used the Very Large Array (VLA) in New Mexico to conduct an observation campaign of one galaxy in particular. This was AGC 114905, a gas-rich, ultra-diffuse dwarf galaxy located about 250 million light-years away in the constellation Pisces. This designation refers to the fact that it is a low luminosity galaxy with far fewer stars than galaxies like ours (despite being comparable in size).

During this campaign, the team collected data on the rotation of gas in AGC 114905 for 40 hours between July and October 2020. They then made a graph that showed the distance of the gas from the center of the galaxy (x-axis) and the rotational speed of the gas (y-axis), which is a standard way of revealing the influence of dark matter. This graph showed that the presence of normal matter alone could explain the motions of the gas in AGC 114905.

As Piña explained in a recent Royal Astronomical Society press release:

“This is, of course, what we thought and hoped for because it confirms our previous measurements. But now the problem remains that the theory predicts that there must be dark matter in AGC 114905, but our observations say there isn’t. In fact, the difference between theory and observation is only getting bigger.”

This is not the first time astronomers observed a galaxy that appeared to have little or no Dark Matter. In 2018, a team of American and Canadian astronomers led by Pieter van Dokkum (Professor of Astronomy at Yale) discovered an ultra-diffuse galaxy (NGC1052–DF2) that was similarly bereft of dark matter. The techniques and measurements employed by Piña and his colleagues provided more robust results.

Stars and galaxies in space

Description automatically generated with medium confidenceHubble image of NGC 1052-DF2, an ultra-diffuse galaxy that appears to have little or no dark matter. Credit: NASA/ESA/P. van Dokkum (Yale University)

In the near future, Piña and his colleagues will examine another ultra-diffuse dwarf galaxy in detail. If they again find no traces of Dark Matter, it will confirm that galaxies are out there that defy the CDM model. This could be good news, as it will apply new constraints on Dark Matter and its role in galactic and cosmic evolution. Most of the great breakthroughs in history happened when experimental results contradicted established models.

Don’t forget our next meeting on Monday, January 10at 4 PM. And please note an article from Hoard that he will discuss tomorrow at the meeting. I

Hoping for a big turnout,

Bob Snodgrass

Howard 's article for the January 10th meeting is in reference to

First results from Hayabusa’s Ryugu asteroid sample.

After a 5 billion km journey, Hayabusa’s treasure hunt yields clues to origin of Earth’s water and organic material.