Goutham Krishna

Let's Explore the Universe

[Goutham Krishna @QuasarJWST74]

@BLACKCAPS Duffy 2 wickets, Jamieson 1 wicket and now Fisher gets Axar Patel!

[Corey S. Powell @coreyspowell]

Astronomers have discovered 11 more moons around Saturn, bringing its total to 285--by far the most of any planet in the solar system.

The true number may be unknowable, if you count every ring particle as its own little moon.

https://t.co/EzkN9ztJ0D

[CERNpress @CERNpress]

[Press Update] LHCb Collaboration discovers new proton-like particle.

Find out more: https://t.co/YphsbwZ2tn

[Erika  @ExploreCosmos_]

Gravitational waves are tiny ripples in the fabric of spacetime produced when extremely massive objects accelerate, such as when two black holes spiral together and collide.

These distortions propagate across the universe, but by the time they reach Earth they are incredibly faint, requiring extraordinarily sensitive instruments to detect them. Over the past decade, observatories such as the @LIGO, Virgo and KAGRA have formed a global network capable of measuring these subtle disturbances in spacetime.

Since the first confirmed detection of gravitational waves in 2015, the number of observed events has steadily increased, allowing scientists to build a growing catalogue of cosmic collisions.

A recently expanded catalogue of gravitational-wave signals has now significantly increased the number of known events, including dozens of new candidate detections produced by mergers of black holes or neutron stars.

Many of these newly identified signals come from systems that are more massive, more rapidly spinning or otherwise more unusual than those previously observed. Each detection effectively acts as a natural experiment in extreme gravity, providing a way to study how spacetime behaves under conditions that cannot be reproduced in laboratories.

These observations are particularly valuable because they allow physicists to test Albert Einstein’s general theory of relativity in regimes where gravitational fields are extremely strong. According to general relativity, gravity is not a force in the traditional sense but a manifestation of how mass and energy warp spacetime, causing objects to move along curved paths.

The gravitational waves emitted during the inspiral and merger of compact objects encode precise information about this curvature. By comparing the observed waveforms with theoretical predictions, researchers can determine whether Einstein’s equations still accurately describe gravity under these extreme conditions.

So far, the growing catalogue of gravitational-wave detections continues to agree remarkably well with the predictions of general relativity. Rather than revealing clear deviations, the new observations are refining the limits within which the theory remains valid.

At the same time, the increasing number of detections is enabling more detailed statistical studies of black hole populations, their masses and spins, and the environments in which they form. In this sense, gravitational-wave astronomy is not only testing fundamental physics but also opening a new observational window into how compact objects evolve throughout cosmic history.

As detector sensitivity improves and observing runs continue, scientists expect to detect many more gravitational-wave events each year. Larger datasets will allow even more stringent tests of Einstein’s theory and may eventually reveal subtle discrepancies that point toward new physics beyond general relativity.

For now, however, the ripples from distant cosmic collisions continue to confirm that Einstein’s description of gravity remains extraordinarily robust, even in the most violent environments in the universe.

👉 https://t.co/n1CToKcyqK

[Goutham Krishna @QuasarJWST74]

@ScholarshipfPhd Hi, I'm interested in doing PhD. I would really appreciate if you could suggest a research topic.

[Goutham Krishna @QuasarJWST74]

@ScholarshipfPhd HI

[Erika  @ExploreCosmos_]

In astrophysics, dead stars represent the final evolutionary stages in the life of a star after it has exhausted the nuclear fuel that sustained it during its active phase. These compact stellar remnants, white dwarfs, neutron stars, and black holes, are the endpoints of stellar evolution, and the specific remnant that forms depends primarily on the original mass of the progenitor star.

White Dwarfs.

White dwarfs form from stars with initial masses less than approximately 8 solar masses. After expanding into red giants and expelling their outer envelopes, often forming a planetary nebula, these stars leave behind a dense core. No longer undergoing fusion, the remnant shines faintly from residual thermal energy and gradually cools over time. White dwarfs have masses below the Chandrasekhar limit (~1.4 solar masses), beyond which electron degeneracy pressure can no longer support the star against gravitational collapse. These remnants are Earth-sized yet can be as massive as the Sun.

Neutron Stars.

Stars with initial masses roughly between 8 and 25 solar masses typically end their lives in core-collapse supernovae (commonly Type II supernovae). The collapsed core, composed almost entirely of neutrons, forms a neutron star. These objects have radii of about 10–15 kilometers and masses between ~1.4 and ~2.1 solar masses. If the remnant's mass stays below the Tolman–Oppenheimer–Volkoff (TOV) limit, neutron degeneracy pressure can support it.

Neutron stars exhibit diverse phenomena:

Pulsars: rapidly spinning neutron stars that emit beams of radiation detectable as pulses.

Magnetars: neutron stars with ultra-strong magnetic fields (~10¹⁵ gauss), which power extreme X-ray and gamma-ray bursts.

Black Holes.

If the stellar core exceeds the TOV limit after a supernova, gravity overwhelms all known forces, leading to the formation of a black hole. These objects contain a singularity, a point of infinite density, surrounded by an event horizon, the boundary beyond which nothing, not even light, can escape. Black holes are classified by mass (stellar-mass, intermediate, and supermassive) and detected indirectly through gravitational effects, accretion disks, or relativistic jets.

Additional Insights and Discoveries.

Recent breakthroughs have illuminated the nature and interactions of dead stars. In 2015, gravitational waves were detected for the first time (GW150914), confirming the merger of two black holes. In 2017, GW170817 revealed a neutron star merger, observed through both gravitational waves and electromagnetic radiation. This event confirmed that such collisions produce heavy elements (like gold and platinum) via rapid neutron capture (r-process) nucleosynthesis and offered key constraints on neutron star equations of state.

Moreover, dead stars are linked to different types of supernovae:

Type II supernovae result from the collapse of massive stars and lead to neutron stars or black holes.

Type Ia supernovae occur in binary systems when a white dwarf accretes matter and exceeds the Chandrasekhar limit, leading to a thermonuclear explosion—these are critical as standard candles for measuring cosmic distances.

With instruments like @chandraxray, #JWST, and @LIGO /Virgo, we continue to uncover how these remnants shape galaxy evolution, interstellar chemistry, and the most extreme physics in the universe. Though termed "dead," these stars remain central actors in the cosmic narrative.

[Fermat's Library @fermatslibrary]

A reminder that there are more terms

[Nereide @Nereide]

Remebering Hannah Arendt’s birthday yesterday, 14 October 1906.

"The moment we no longer have a free press, anything can happen. What makes it possible for a totalitarian or any other dictatorship to rule is that people are not informed; how can you have an opinion if you are not informed?"

Hannah Arendt reminds us how fragile democracy is without truth.

Quote Source: Hannah Arendt, interview with Roger Errera, conducted in 1974, published in The New York Review of Books, October 26, 1978; titled "Hannah Arendt: From an Interview."

Available online at➡️https://t.co/A1CXOykupu

Image: Photograph of Hannah Arendt in 1933. Public Domain
Author: Unknown
Via Wikimedia Commons

#HannahArendt #FreePress #Democracy

[Goutham Krishna @QuasarJWST74]

@ScholarshipfPhd Hi! Please share the book link.

[Goutham Krishna @QuasarJWST74]

@premierleague 1: Newcastle United
2: Nottingham Forest
3: Aston Villa
4: Liverpool
5: Bournemouth
6: Brighton and Hove Albion
7: Brentford
8: Crystal Palace
9: Manchester United
10: Leeds United
11: Burnley
12: Sunderland
13: Tottenham Hotspur
14: Everton
15: Fulham
16: West Ham United

[Goutham Krishna @QuasarJWST74]

@SkyBetLeagueOne Promotion:
Bolton Wanderers
Port Vale

Promotion Play-off final:
Luton Town(W) vs Blackpool(L)

Relegation:
Cardiff City
Reading
Rotherham United

[Goutham Krishna @QuasarJWST74]

@SkyBetChamp Promotion:
Ipswich Town
Coventry City

Promotion Play-off final:
Middlesbrough(W) vs Norwich City(L)

Relegation:
Queen's Park Rangers
Derby County
Portsmouth

[Goutham Krishna @QuasarJWST74]

@SkyBetLeagueTwo Promotion:
Bromley
Bristol Rovers
Barnet

Promotion Play-off final:
Barrow(L) vs Chesterfield(W)

Relegation:
Salford City
Shrewsbury Town

[Derek Wang @derekhxw]

The origin of this joke came from the following thinking: in classical mechanics with Hamiltonian formulation, energy is the Hamiltonian H = E = T + V (total energy is the sum of kinetic energy and potential energy), if no potential energy, H = T = 1/2 mv^2. In quantum mechanics, Schrödinger turned H into an operation on a wavefunction, thus we have Schrödinger Equation.

In specially relativity, Einstein derived the famous energy formula: E^2 = (pc)^2 + (m0 c^2)^2 (which reduces to E = m c^2 when the object is stationary). Notice the square of energy in the formula. When Dirac tried to use same trick as Schrödinger by turning E into an operator H, he faced the problem of how to take the square root of a matrix (due to electron spin). Furthermore, square root of any number has two solutions: + and -, thus this naturally led to matter and antimatter. Thus we have Dirac Equation.

[Physics In History @PhysInHistory]

Niels Bohr on Paul Dirac ✍️

Dirac was the strangest man who ever visited my institute. During one of Dirac’s visits I asked him what he was doing. He replied that he was trying to take the square-root of a matrix, and I thought to myself what a strange thing for such a brilliant man to be doing. Not long afterwards the proof sheets of his article on the equation arrived, and I saw he had not even told me that he had been trying to take the square root of the unit matrix!

[Goutham Krishna @QuasarJWST74]

25 Amazing Discoveries(1999-2024) https://t.co/FDMk6MSPns

[Goutham Krishna @QuasarJWST74]

@SPACEdotcom Sir, could you please send the pdf of the published article?

[UEFA @UEFA]

🏆 A first European final and a VICTORY!

💙🖤💙 Complimenti @Atalanta_BC!

@EuropaLeague | #UELfinal | #UEL