Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: cosmology – Page 4

A Giant Star Vanished, And Scientists Think a Black Hole Is to Blame

One of the brightest stars in the Andromeda galaxy quietly collapsed into a black hole without any of the fanfare of a spectacular supernova.

What makes this startling discovery even more remarkable is that the first signs of the transformation were recorded back in 2014 – data that is crucial for understanding the different ways black holes can form after the death of a giant star.

“This has probably been the most surprising discovery of my life,” says astronomer Kishalay De of Columbia University in the US, who led the research. “The evidence of the disappearance of the star was lying in public archival data, and nobody noticed for years until we picked it out.”

A possible first-ever Einstein probe observation of a black hole tearing apart a white dwarf

On July 2, 2025, the China-led Einstein Probe (EP) space telescope detected an exceptionally bright X-ray source whose brightness varied rapidly during a routine sky survey. Its unusual signal immediately set it apart from ordinary cosmic sources, triggering rapid follow-up observations by telescopes worldwide.

Study of the event was coordinated by the EP Science Center of the National Astronomical Observatories, Chinese Academy of Sciences (NAOC), with participation from multiple research institutions in China and abroad. Astrophysicists from the Department of Physics at The University of Hong Kong (HKU), who are integral members of the EP scientific team, worked together with the broader collaboration to interpret the event, proposing that it may mark the moment when an intermediate-mass black hole tears apart and consumes a white dwarf star.

If confirmed, this would be the first observational evidence of such an extreme black hole “feeding” process. The findings have been published as a cover article in Science Bulletin.

The Computer That Consumes Stars

And a black hole would be a type of computer if we could use it.

What is the ultimate limit of a civilization? It isn’t conquering a galaxy. It is processing power.

A “Matrioshka Brain” is a megastructure so massive it encases an entire star. It is a Dyson Sphere upgraded to God-Mode. Instead of just harvesting energy, it uses the star to fuel a computer powerful enough to simulate trillions of universes.

If a civilization builds one of these, they don’t need to explore space. They can upload their minds to a digital heaven and live forever. This might be the terrifying reason why the universe is so silent.

Chapters:

Continue reading “The Computer That Consumes Stars” | >

Old galaxies in a young universe?

The standard cosmological model (present-day version of “Big Bang,” called Lambda-CDM) gives an age of the universe close to 13.8 billion years and much younger when we explore the universe at high-redshift. The redshift of galaxies is produced by the expansion of the universe, which causes emitted wavelengths to lengthen and move toward the red end of the electromagnetic spectrum.

The further away a galaxy is, the more rapidly it is moving with respect to us, and so the greater is its redshift; and, given that the speed of light is finite, the more we travel to the past. Hence, measuring the age of very high redshift galaxies would be a way to test the cosmological model. Galaxies cannot be older than the age of the universe in which they are; it would be absurd, like a son older than his mother.

In work carried out with my colleague, Carlos M. Gutiérrez, at the Canary Islands Astrophysics Institute (IAC; Spain), we analyzed 31 galaxies with average redshift 7.3 (when the universe was 700 Myr old, according to the standard model) observed with the most powerful available telescope available: the James Webb Space Telescope (JWST).

Experiment relies on pulsars to probe dark matter waves

Dark matter is a type of matter that is predicted to make up most of the matter in the universe, yet it is very difficult to detect using conventional experimental techniques, as it does not emit, absorb, or reflect light. While some past studies gathered indirect hints of its existence, dark matter has never been directly observed; thus, its composition remains a mystery.

One hypothesis is that dark matter is made up of axionlike particles with an extremely low mass, broadly referred to as ultralight axionlike dark matter (ALDM). As these particles are exceedingly light, predictions suggest that they would behave more like waves than individual particles on a galactic scale.

The PPTA collaboration, a large team of researchers based at different institutes worldwide, applied a new approach to search for ALDM by cross-correlating polarization data of pulsars, neutron stars that spin rapidly and emit highly regular beams of radio waves. This approach, termed the “Pulsar Polarization Array (PPA),” entails measuring the polarization position angles of a series of pulsars and how they changed over time and with respect to pulsar spatial position.

Scientists show how to narrow the hunt for merging giant black holes

A new detection framework explains how astronomers can isolate extremely slow gravitational wave signals.

By combining subtle distortions in spacetime with observations of unusually bright galactic centers, the study authors have demonstrated a practical method for identifying likely locations of merging supermassive black holes.

Pulsar timing hints at a nearby dark matter ‘sub-halo’

A group of US astronomers may have uncovered the first evidence for a dark matter sub-halo lurking just beyond our stellar neighborhood. Reporting their findings in Physical Review Letters, a team led by Sukanya Chakrabarti at the University of Alabama in Huntsville suggests that an unseen clump of dark matter could be subtly tugging on nearby pulsars. If confirmed, the result could shed new light on the elusive nature of dark matter and how it is distributed throughout our galaxy.

Despite never having been observed directly, astronomers estimate that dark matter makes up around 85% of the total mass of the universe. According to the best available cosmological models, this invisible material forms vast, diffuse “halos” that completely envelop the flat disks of galaxies like the Milky Way. These halos, in turn, should be populated by numerous smaller structures known as dark matter sub-halos.

If theoretical predictions are correct, such sub-halos should be abundant throughout the galaxy. Yet even with masses potentially exceeding tens of millions of times that of the sun, their limited gravitational influence on visible matter has so far made them extraordinarily difficult to detect.

Supermassive black hole at heart of the Milky Way is approaching the cosmic speed limit

“Discovering that Sgr A is rotating at its maximum speed has far-reaching implications for our understanding of black hole formation and the astrophysical processes associated with these fascinating cosmic objects,” Xavier Calmet, a theoretical physicist at the University of Sussex who was not involved in the research, told Live Science in an email.

Related: Black holes: Everything you need to know

A black hole’s spin is different from those of other cosmic objects. Whereas planets, stars and asteroids are solid bodies with physical surfaces, black holes are actually regions of space-time bounded by an outer nonphysical surface called the event horizon, beyond which no light can escape.

Big Bang Thought of the Day by Nobel Laureate Peter Higgs, “The Big Bang made the universe explode into existence. The Higgs boson made it stay.” How Peter Higgs’ “God Particle” settled decades of competing universe theories

Big Bang Thought of the Day by Nobel Laureate Peter Higgs, “The Big Bang made the universe explode into existence. The Higgs boson made it stay.” The universe formed 13.8 billion years ago. But matter could not exist without mass. In 1964, Peter Higgs proposed a solution. His Higgs boson explains why particles gained weight after the Big Bang. Confirmed in 2012 at CERN, it settled decades of cosmic theory conflicts. This discovery reshaped modern physics and cosmology forever.

/* */