Type: Prelims Only

This newscard is an excerpt from the original article published in The Hindu.

Another space-based abstract terminology has appeared in TH.

What is the news about?

• Many stars, towards the end of their lifetimes, form supernovas – massive explosions that send their outer layers shooting into the surrounding space.
• Most of the energy of the supernova is carried away by neutrinos – tiny particles with no charge and which interact weakly with matter.
• Researching the mechanisms of the so-called Type II supernovas, a team from IIT Guwahati has come up with new insights into the part played by neutrinos in this dramatic death of massive stars.

What are Neutrinos?

• Proton, neutron, and electron are tiny particles that makeup atoms.
• The neutrino is also a tiny elementary particle, but it is not part of the atom.
• Neutrino has a very tiny mass, no charge and spins half.
• It interacts very weakly with other matter particles.
• Neutrinos come from the sun (solar neutrinos) and other stars, cosmic rays that come from beyond the solar system, and from the Big Bang from which our Universe originated.
• They can also be produced in the lab.

Their types

• Neutrinos come in three ‘flavours’, another name for ‘types’, and each flavour is associated with a light elementary particle.
• For instance, the electron-neutrino is associated with the electron; the muon-neutrino with the muon and the tau-neutrino with the tau particle.

What is Supernova?

• All the stars burn nuclear fuel in their cores to produce energy.
• The heat generates internal pressure which pushes outwards and prevents the star from collapsing inward due to the action of gravity on its own mass.
• But when the star ages and runs out of fuel to burn, it starts to cool inside.
• This causes a lowering of its internal pressure and therefore the force of gravity wins; the star starts to collapse inwards.
• This builds up shock waves because it happens very suddenly, and the shock wave sends the outer material of the star flying. This is what is perceived as a supernova. This happens in very massive stars.

Try this PYQ:

Q. Which of the following is/are cited by the scientists as evidence/evidence for the continued expansion of the universe?

1. Detection of microwaves in space
2. Observation of redshirt phenomenon in space
3. Movement of asteroids in space
4. Occurrence of supernova explosions in space code

(a) 1 and 2 only

(b) 2 only

(c) 1, 3 and 4

(d) None of the above can be cited as evidence

The Type-II Supernova

• In stars that are more than eight times as massive as the Sun, the supernova is accompanied by a collapsing of the inner material of the dying star – this is also known as core-collapse supernova or Type II supernova.

Role of neutrinos

• The collapsing core may form a black hole or a neutron star, according to its mass.
• As they spew out of the raging supernova, the neutrinos can change from one flavour to another in a process known as neutrino oscillations.
• Due to the high density and energy of the supernova, it generates neutrino oscillations happening simultaneously over different energies (unlike normal neutrino oscillation), termed collective neutrino oscillation.
• The oscillation result may dramatically change when one allows the evolution with the angular asymmetry, the oscillations can happen at a nanosecond time scale, termed fast oscillation.

Space scientists from the University of Sussex have found a new way to know more about dark matter. They have narrowed down the range of masses within which particles that could make up dark matter may lie in.

What is the news about?

• Around 95 % of the Universe is unknown to human beings.
• It is often referred to as dark which has nothing to do with the colour of any substance but to do with the unknown nature of cosmic entities known as dark matter and dark energy.

Trending in news these days is the Quantum Technology. (as it used to be until last year were- the Internet of Things (IoT) CSP 2019, Artificial Intelligence (AI) etc.)

Must read all this news in a loop:

1. National Mission on QC
2. Quantum Coin
3. Quantum Supremacy
4. Quantum Entanglement

What is Dark Matter?

• Dark matter is composed of particles that do not absorb, reflect, or emit light, so they cannot be detected by observing electromagnetic radiation.
• Dark matter is a form of matter thought to account for approximately 85% of the matter in the universe and about a quarter of its total mass-energy density or about 2.241×10⁻²⁷ kg/m³.

What does the research say?

• Scientists carried out the research using quantum gravity, a field of study that tries to combine two of Einstein’s concepts — quantum physics and general relativity theory of gravity.
• This is the first time anyone has thought of using what we know about quantum gravity to calculate the mass range for dark matter.
• Their research shows that the dark matter particles can neither be super light nor super heavy unless there is a force acting on it that is yet unknown.

Quantum gravity: The concept

• Quantum gravity is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics.
• Quantum mechanics is a fundamental theory in physics which describes nature at the smallest scales of energy levels of atoms and subatomic particles.
• Here quantum effects cannot be ignored, such as in the vicinity of black holes or similar compact astrophysical objects where the effects of gravity are strong, such as neutron stars.

Significance of the findings

• This might help in finding out more about this mysterious force. There are currently four known forces in the Universe — gravitational, electromagnetic, weak and strong.
• Scientists estimate that roughly 68 per cent of the Universe is made up of dark energy which is responsible for the accelerated expansion of the Universe.
• Another 27 per cent is a dark matter whose existence was inferred from the observation that ordinary matter in galaxies, including the Milky Way, is far less than that required by gravity to hold the galaxies together.

Why does the ‘Dark Matter’ matter?

• Dark matter’s gravitational effects are also necessary to explain the motions of clusters of galaxies and the structure of the entire Universe at the largest scale.
• On smaller scales, dark matter is too diffused to impact the motion of the Solar System, Earth or the origin and evolution of humans in any significant way.
• But the nature of that dark matter is still unclear. It is most likely made of particles that do not couple to light because of which humans cannot see them.