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Episode 112 – Brown Dwarfs, Dark Matter and Dark Energy

By Gurbir Dated: March 15, 2024 Leave a Comment

This episode was recorded in Tenerife with Professor Eduardo L Martín who is based at the Instituto de Astrofísica de Canarias. He is working on the European Space Agency’s mission, Euclid.

In time Euclid will shed light on both dark matter and dark energy. It was launched in July 2023 and arrived in its L2 orbit a month later. It has just two instruments which will produce a high-resolution 3-D map of a third of the sky, stretching back 10 billion years during its initial 6-year operational lifetime.

Professor Martín is not part of the Euclid Consortium the around 2500 scientists and engineers from more than a dozen countries who operate the Euclid Mission. He is one of the two Euclid mission Independent Legacy Scientists. Professor Martín is a specialist in substellar bodies, that is celestial bodies with a size about that of Jupiter but with around 50 times its mass. When initially theorised in the 1960s they were called Black Dwarfs but renamed in the 1970s by Jill Tarter as Brown Dwarfs.

Brown Dwarfs generate energy only through gravitational compression, not nuclear fusion. There is an overlap in surface temperature between young brown dwarfs and old very low-mass stars. Martín and his collaborators have developed spectroscopic methods to distinguish brown dwarfs from stars, in particular the Lithium test. More about this interesting role of Lithium in cosmology in Professor Martín’s book published in 2023 by the Institute of Physics, entitled “Lithium Across the Universe“. You can download several free-to-read chapters – here.

Brown Dwarfs emit mostly in the infrared not optical light as our sun. One of the two instruments on Euclid operates in the infrared and can detect these “dark ultracold objects of substellar mass“. Does Professor Martin think Euclid will find Brown Dwarfs? He told me in this recording, “that is what I put in the proposal so we had better do now”. He is supported by a postdoc Marusa Zerjal and a student Diego Martin, funded by the European Research Council.

The first images were released in November 2023. The spacecraft and its instruments are operating well and sending data. More about the Euclid mission, images released so far and a summary of the attributes of Normal Matter, Dark Matter and Dark Energy below.

Episode112 ESA’s Euclid Mission with Professor Eduardo Martin

Perhaps the most pressing question for astrophysicists is what is the cosmos made of. They have known for a long time that visible matter accounts only for the 5%, Dark Matter, 27% and Dark Energy 68%. Currently, most of the attributes of Dark Matter and Dark Energy remain a mystery. Helping to shed some answers to these questions is Euclid’s primary goal.

The visible matter is something we are surrounded by. It responds to all 4 known forces, electromagnetic, gravitation, and the strong and weak nuclear force. Dark matter is not dark, it’s invisible and is only detected through its gravitational influence on the matter we can see. Gravitational lensing is one manifestation.

Whereas gravity is a force of attraction, Dark Energy is repulsive, powering the expansion of the Universe. Its effects are observed by monitoring type 1a supernovae in distant galaxies. Some scientists consider Dark Energy as the Cosmological Constant that Einstein initially added and then removed from his General Theory of Relativity. The Cosmological Constant is now considered by some as the 5th fundamental force, after gravity, electromagnetism, and strong and weak nuclear forces.

  • Horse head Nebula. Credit ESA
  • Globular Cluster NGC6397. Credit ESA
  • Irregular Galaxy NGC6822. Credit ESA
  • Spiral galaxy IC342. Credit ESA Credit ESA
  • Perseus Cluster. Credit ESA

Summary of attributes for Normal Matter, Dark Matter and Dark Energy

AttributeNormal MatterDark MatterDark Energy
Formation TimeShortly after the Big BangLikely formed shortly after the Big BangBelieved to have originated with the expansion of the universe
LocationEverything we can see including Galaxies, stars, planets and the interstellar mediumPrimarily in galactic halos, halos around galactic clusters and permeates the universeHomogeneously distributed throughout space, associated with vacuum energy
Observational EvidenceEmission and absorption spectra, visible light, X-rays, cosmic microwave backgroundGravitational effects on visible matter, galaxy rotation curves; Dark matter inferred from galaxy cluster dynamics by Fritz Zwicky, 1933). Galaxy rotation curves suggest dark matter and the work of Vera Rubin from the 1970s.
Observation of gravitational lensing.
Acceleration of cosmic expansion, distant Type 1a supernova observations by Saul Perlmutter, Brian Schmidt, Adam Riess (1998-1999).
In time, it may turn out to be the 5th fundamental force.
Interaction with Electromagnetic ForceStrong interaction, contributes to various spectra and emissionsWeak or non-existent interactions with light and other EM wavesWeak or non-existent interactions with light and other EM waves
Interaction with Gravitational ForceExperiences gravitational attraction with other matterExperiences gravitational attraction, influencing cosmic structures. Exhibits a repulsive gravitational effect, driving cosmic expansion
Percentage Composition in the Universe~4.6% of the total mass-energy content~26.5% of the total mass-energy content~68.9% of the total mass-energy content
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Episode 111 – Chandrayaan-3

By Gurbir Dated: November 30, 2023 1 Comment

Project Director P Veeramuthuvel, Associate Project Director: Kalpana Kalahasti  and ISRO Chairman: S. Somanath
Project Director P Veeramuthuvel, Associate Project Director: Kalpana Kalahasti and ISRO Chairman: S. Somanath

Traditionally an ISRO live stream event ends with a few short speeches from the ISRO chairman and several of the key personnel associated with the mission. On 23 August 2023, following the successful soft landing of Chandrayaan-3 lander, this tradition played out as normal. But this time, along with chairman Somanath on the stage was the Chandrayaan-3 Associate Project Director, Kalpana Kalahasti. Although ISRO has many female scientists, engineers and managers, this was the first time (to my knowledge) for a woman to make it to the stage during the live stream.

A qualified communications engineer, Kalapana Kalahasti has worked on several mission including the 2013 Earth observation satellite called SARAL, jointly with the French Space Agency CNES.

She was assigned as the Associate Project Director for Chandrayaan-3 in 2019 following the unsuccessful Chandrayaan-2 landing attempt. In this conversation she recalls her journey with ISRO from 1999 when she joined as a radar engineer based at Sriharikota.

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Episode 110 – Humanity’s spiritual destiny and the 100 year starship

By Gurbir Dated: November 10, 2023 Leave a Comment

Nasa astronaut Dr Mae Jemison
Nasa astronaut Dr Mae Jemison. Credit NASA

NASA has dared and accomplished many “mighty things”. Not a NASA project but to reach the stars in 100 years is just as mighty.

The 100 year starship project aims to get humanity to travel to the stars in one hundred years time. It started in 2012 headed by Dr Mae Jemison the first woman of colour to fly in to space in STS 47 in 1992.

Jason Batt has several eclectic interests he is also the Creative and Editorial Manager for the www.100yss.org project. In a wide ranging discussion in BAKU during the IAC2023, we discussed the role of science fiction, mysticism and spirituality in humanity’s distant future.

Listen (or watch if on youtube) to the end for a clip of Dr Mae Jemison talking about the 100 Year Starship Manifesto. You can see it in its entirety here.

Audio and vido for episode 110 below. Episode 25 has more on science and religion.

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The day the Cosmonaut came to Manchester

By Gurbir Dated: April 28, 2023 Leave a Comment

This piece was first published in Manchester Histories blog on 12 April 2023


Gagarin and British PM McMillan
Yuri Gagarin with the Prime Minister for the second time on 13th July 1961 (Courtesy RIA Novosti)

On Wednesday, 12th April 1961, a bright and sunny spring morning, an air force pilot of the USSR launched into space using a modified intercontinental ballistic missile. On his first trip outside the USSR,  Yuri Gagarin, aged 27 went -around the world in just 90 minutes. He broke the world altitude and speed records. He was the first to experience the realm and sensation of being in space. Exactly three months later, he came to Manchester.

He arrived at Ringway airport at around 10am on Wednesday, 12th July and travelled first to the Headquarters of his hosts, the Amalgamated Union of Foundry Workers (AUFW) in Old Trafford. It was a sunny day but peppered with occasional sharp showers typical in July. Thousands lined his route from Ringway to Old Trafford.  Travelling in an open-top Bently, he received a true Mancunian welcome. He was soaked. In the small union HQ, he was made an honorary member of the AUFW and President Fred Hollingsworth presented him with a medal engraved with the words “Together, moulding a better future”. 

His second stop was Metropolitan Vickers in Trafford Park, a unique place in Machester’s history of the industrial revolution. By now, the rain had stopped but puddles hinted at the recent downpour. Stanely Nelson recalled shaking Gagarin’s hand near the foundry. He recalled the working conditions most foundry workers endured saying, “it was like a vision of hell. Smoke, fire and tiny thin men silhouetted against the foundry fire. No one was fat; they were all thin like Lowry’s match stick men”. Of all his time in Britain, it was this time surrounded by working men and women amongst the dirt and grime of a working foundry that Gagarin would later say he felt most at home.

He arrived at Manchester Town Hall for a formal civic reception hosted by the Lord Mayor. Albert Square and all the surrounding office windows and doorways were crammed with people waiting to see the only man with the experience of Earth orbit. The dignitaries who got to shake his hand included Bernard Lovell from Jodrell Bank and the mathematician Kathleen Ollerenshaw. At the Town Hall, Gagarin, speaking in Russian, expressed his wishes for future space missions saying, ”I would like naturally like to fly to the Moon then perhaps to Mars and Venus and even further if my abilities make it possible”. By 16:30, he was at Ringway on his flight back to London, where he had arrived the day before and would stay until his return flight to Moscow on Saturday, 15th July. 

His spaceflight was packed with risk. He had left his wife a letter saying that should he not return, a real possibility, she should not remain alone. He experienced problems at launch and another during re-entry. The service module separation did not go to plan. The mission and his life came close to a catastrophic end. Ejecting from his spacecraft and landing separately by parachute, he returned to Earth as a real-life superhero. It was a supreme technological triumph, fulfilling humanity’s age-old dream of leaving Earth. It was achieved by a nation championing the virtues of communism in the midst of the Cold War. This was his first visit to the heart of the democratic West to demonstrate the prowess of the communist way of life.

To avoid highlighting the USA’s failure (its ally) to “be the first”, the UK government could not offer Gagarin a formal invitation. The remarkable response on his first day in London on 11th July, the public turned out in their thousands lining the streets in London and inundating Earls Court, the venue of the Soviet Trade Fair. Before the day was out, he had received an invitation from the Prime Minister, Harold Macmillan and the Queen. His initial two-or-three-day UK visit was extended to five.

Following the global coverage of his flight in April, AUFW President Fred Hollingsworth discovered that Gagarin had trained as a Foundry Worker. It was the invitation the AUFW made in May of 1961 that brought Gagarin to Manchester.  Gagarin met the Prime Minister at the Admiralty and the Queen in Buckingham Palace, along with other visits to the Air Ministry, Mansion House and the Royal Society at Burlington House. In April 1962, the first anniversary of his flight, Gagarin sent a message to the people of Manchester saying, “And the firm handshakes of my fellow workers in the moulding shop were dearer to me than many awards”. For the many who saw or met Gagarin recalled his charm, good looks and his persistent smile.

Gagarin’s visit coincided with the heightened risk of another world war. The Bay of Pigs invasion, the end of the ban on nuclear weapons testing, the building of the Berlin Wall and the Cuban Missile Crisis. He was probably aware of the rising geopolitical tensions more than most. While in Manchester and London, Gagarin repeated his message of peace. Despite his extraordinary achievement, the people of Manchester saw an ordinary man with humble roots. For most, he was probably the only individual from the USSR they would ever meet.

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