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#171 - Dark Matter


This week we have a chat about dark matter and an intriguing new idea of what this mysterious missing mass of the universe is. We also have a quick catch up on all things space this week, returning astronauts, even more internet satellites, Russian spies, starliner woes!



“Energy is liberated matter, matter is energy waiting to happen.”

Bill Bryson


OTD 7th Feb 1984 – Space Shuttle program: STS-41-B Mission: Astronauts Bruce McCandless II and Robert L. Stewart make the first untethered spacewalk using the Manned Maneuvering Unit (MMU).


Happy Birthday Apollo Astronaut and guest on an early podcast Mr Alfred Worden and also Astronaut Heidemarie Martha Stefanyshyn-Pipe





Space News

UK based OneWeb launched 34 sats last night from Baikonur on the Soyuz with the Fregat-M, The aim is to have the full network in operation by the end of 2021.


Back To Earth



Soyuz MS-13 successfully landed in Kazakhstan early Thursday, returning the three International Space Station crew at 4:12 a.m. Eastern, only three and a half hours after undocking from the station. Christina Koch, ESA astronaut Luca Parmitano and Roscosmos cosmonaut Alexander Skvortsov



A Russian "inspector" satellite appears to be shadowing an American reconnaissance satellite. Publicly available tracking data shows that Cosmos-2542 has synchronized its orbit with USA 245, widely believed to be a KH-11 reconnaissance satellite. Cosmos-2542 lasted last November and deployed a small satellite, Cosmos-2543, as a test of its inspection capabilities. Satellite observers believe that Cosmos-2542's close approaches to USA 245 are unlikely to be a coincidence, but it's unclear what activities Cosmos-2542 is performing while in the vicinity of USA 245


Starliner Woes

There was a serious issue with software on Boeings Starliner that could have been a total loss of vehicle if not spotted and corrected, it was revealed at a hearing.



SpaceX may spin off Starlink into a separate business and go public,

“That particular piece is an element of the business that we are likely to spin out and go public, Right now, we are a private company, but Starlink is the right kind of business that we can go ahead and take public.” Shotwell revealed.


Dark Matter Special!

When you look into space you can’t actually see most of the universe. I don’t mean that you can’t see the stars because the clouds are in the way. Even the Hubble space telescope is blind to at least 85% of the stuff out there!! So what exactly are we talking about

Dark Matter!!

But why can’t we see it? is it dark like a very black rock in space, not reflecting any starlight? ...probably not, It’s something that is everywhere but doesn’t interact with light or any type of electromagnetic radiation, so can’t be felt or seen by any known instrument, including our skin or eyes!!

So if you can’t see it and it doesn’t interact with anything why do we think it is there?


Enter Lord Kelvin.


William Thomson; Born nearly 200 years ago in Belfast was inspired to move into working in science by the following lines from Alexander Pope


Go, wondrous creature! mount where Science guides;

Go measure earth, weigh air, and state the tides;

Instruct the planets in what orbs to run,

Correct old Time, and regulate the sun;


His early work was very much involved with the work of Carnot and Joule, and his work along with Joule would lay down and often state laws of Thermodynamics (including the heat death of the Universe) but also that eventually, you would get to a state of no energy, hence the Kelvin scale, we will come back to Thermodynamics.

He was knighted when he was involved in laying the great transatlantic cables, helping faraday devising their bandwidth, and many other innovations in data technology, we’ll come back to this too.


Despite being a creationist he always thought the universe followed the laws of thermodynamics and that a dynamic system created the universe and the solar system and tried to show the age of the earth through the way it cooled down. He also gave a lecture in 1900 that alluded to two dark clouds in physics to the Royal Institute, The Movement of matter through the Aether and how the statistics of temperature relating to energy systems may break down. Both solved by Einstein 5 years later. What he didn’t know is earlier he had hinted at another Dark cloud.


In 1884 Kelvin had used the velocity of stars orbiting the galaxy to determine the mass of the Galaxy, which he soon determined was far greater than the mass of the visible stars, Lord Kelvin said


"many of our stars, perhaps a great majority of them, may be dark bodies".


Over 20 years later, and the year after Einsteins Annus mirabilis. Henri Poincaré in "The Milky Way and Theory of Gases" used "dark matter", or "matière obscure" while discussing Kelvin's 1884 paper.


Then the Dutch took over, Kapteyn,1922 and fellow dutchman Oort in 1932 also using stella velocities hinted at dark matter.


Swiss astrophysicist Zwicky was next on the case, not content with stars moving around galaxies he used galaxies moving around galaxy clusters! And again found enormous amounts of “Dunkle Materie”




In the 1970s Vera Rubin and Kent Ford used even more accurate ways to measure the velocity curves of spiral galaxies and in 1980 their paper showed pretty conclusively that galaxies contain about 6 times the mass of visible stars in some invisible form. Dark matter was widely recognized as a major unsolved problem in astronomy (still a bone of contention for a female Nobel snub)




Of course, the 80’s was an explosion in technological Astronomy, radio telescopes could measure even further out, adding evidence. Added to this was gravitational lensing and caused by dark matter, in other words starlight being bent by Gravity (Einstein) by an object that doen’t seem to be there. Distribution of Gas in galaxies (Chandra etc) the variations of the pattern in the CMB as discussed in podcast 123 Baryonic Acoustic Oscillations.


Basically the consensus is that this invisible matter must be a substance made by a completely new subatomic particle and finding this particle is now one of the major goals of physics!!!


There is Baryonic Matter, pretty much everything made from atoms that have mass but not Dark Matter, so there is also a missing Baryon problem in the universe, observed amount of baryonic matter did not match theoretical predictions, considered solved in 2017, but that should not be confused with the dark matter which is much more unexplained.


The Bullet Cluster as mentioned by Grant on our Chandra special provides a stunning piece of evidence and closes another plausible explantation to dark matter and that is a modified theory of gravity. The apparent centre of mass is displaced a huge distance from the obvious normal baryonic centre of mass, simply not feasible in modified gravity theory.

Candidates.


Credit: G. Bertone and T. Tait


Can you have Dark Matter Planets and other types of familiar normal matter objects, like a huge dark matter asteroid or comet ….probably not

As Dark matter only seems to act through gravity it may not be able to lose energy efficiently which would make forming objects very difficult. Also objects like planets form via multiple interactions not just gravity, they need electromagnetic and other forces to actually bind.

dark matter is thought to comprise up to 27% of the universe. "Normal" or baryonic matter makes up just 5%. That's the stuff we can detect. Dark energy, which we can't detect either, makes up 68%

There are loads of explanations but one that blew my mind last week.

Remember 1906 and Einstein Annnus miribalilis and his equation E=MC^2 is a classic from this and leads to the mass-energy equivalence. For example if you squeeze a giant spring, it now has a lot of potential energy stored within it, this has actually made the spring heavier! You can also release the mass of an atom’s nucleus and have a nuclear bomb!

Dr. Melvin Vopson of the University of Portsmouth, here in the UK, postulates the mass-energy-information equivalence. It states that information is the fundamental building block of the universe, and it has mass.

Ignoring any particular features of the event, the observer or the observation method, Claude Elwood Shannon developed a theory in which he defined information extracted from observing an event as a function of the probability of the event to occur or not, I(p). A key measure in information theory is "entropy". the outcome of a fair coin flip, provides less information (lower entropy) than specifying the outcome from a roll of a six sided die

Maxwell’s Demon, controls a small door between two chambers of gas. As individual gas molecules approach the door, the demon quickly opens and shuts the door so that only fast molecules are passed into one of the chambers, while only slow molecules are passed into the other. Because faster molecules are hotter, the demon's behaviour causes one chamber to warm up and the other to cool down, thereby decreasing entropy and violating the second law of thermodynamics. However this little conundrum seems to have been vanquished by Information theory most importantly the Landauer's principle "any logically irreversible manipulation of information, such as the erasure of a bit or the merging of two computation paths, must be accompanied by a corresponding entropy increase in non-information-bearing degrees of freedom of the information-processing apparatus or its environment, This absolutely connects Energy in some way to Information and is why Information is considered so fundamental in modern physics and has been backed up through experiments over the years.

In Vopson's theory, information, once created has "finite and quantifiable mass." It may only apply to digital systems, but what if it applied to analogue and biological or quantum ones too,

This may not be as radical as it seems The great Professor Wheeler use to say “it from Bit”

Wheeler announced that everything, from particles to forces to the fabric of spacetime itself "… derives its function, its meaning, its very existence entirely … from the apparatus-elicited answers to yes-or-no questions, binary choices, bits."

So Vopson, is proposing that a bit of information is not just physical, as already demonstrated, but it has a finite and quantifiable mass while it stores information. He goes on to show that the mass of a bit of information at room temperature (300K) is 3.19 × 10^-38 Kg. (30 undecillionths) To test the hypothesis we propose here an experiment, predicting that the mass of a data storage device would increase by a small amount when is full of digital information relative to its mass in erased state. For 1Tb device, the estimated mass change is 2.5 × 10-25 Kg (¼ of a Yoctogram)

by providing viable arguments that the physical nature of digital information requires a bit of information to have a very small, non-zero mass. This is a very abstract concept with some speculative aspects, but it has the virtue of being verifiable in a laboratory environment

Nothing is capable of weighing to this accuracy, "Currently, I am in the process of applying for a small grant, with the main objective of designing such an experiment, followed by calculations to check if detection of these small mass changes is even possible," Vopson says.

"Assuming the grant is successful and the estimates are positive, then a larger international consortium could be formed to undertake the construction of the instrument." He added, "This is not a workbench laboratory experiment, and it would most likely be a large and costly facility." If eventually proved correct, Vopson will have discovered the fifth form of matter.

Assuming that all the missing dark matter is in fact information mass, the initial estimates indicate that ∼1093 bits would be sufficient to explain all the missing dark matter in the visible Universe. Remarkably, this number is reasonably close to another estimate of the Universe information bit content of ∼1087 given by Gough in 2008 via a different approach




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