Lifeboat Foundation

Geoff Bennett:

Let’s expand our horizons a bit wider and look at important findings that are literally about space-time and the cosmos as we know it.

You might remember that Albert Einstein theorized that as heavy objects move through time and space, they create ripple effects in the fabric of our universe. Now an international team of scientists have detected new evidence of that. Researchers found new signs of gravitational waves, waves that are affected by huge movements, such as the collision of black holes.

Since the discovery of gravitational waves, scientists have been trying to understand the origin of merging black holes, and POSYDON may be the way to do it.

Black holes are some of the most fascinating celestial bodies in the universe. Their gravitational fields are so strong that even light cannot escape them. One of the ways in which they are formed is when a massive star collapses, resulting in a stellar-mass black hole.

In 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) discovered gravitational waves (ripples through spacetime) from two colliding black holes. This groundbreaking discovery has prompted astrophysicists to study their origin and formation.

For the first time, researchers using pulsar timing arrays have found evidence for the long-sought-after gravitational wave background. Though the exact source of this low-frequency gravitational wave hum is not yet known, further observations may reveal it to be from pairs of supermassive black holes orbiting one another or from entirely new physics at work in our universe.

A New Window onto Gravitational Waves

In 2016, researchers reported the first detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO), opening a new window onto a universe’s worth of collisions between extreme objects like black holes and neutron stars. Though this discovery marked the beginning of a new observational era, many sources of gravitational waves remained beyond the reach of our current detectors on Earth.

In less time than it takes to snap your fingers, the universe flashed into existence.

Cosmogenesis is the breathtaking story of how this happened. It includes, in its later moments, the creation of the primordial elements and depicts their organization by dark matter and gravity into vast cosmic structures on the largest scales. Meanwhile, on smaller scales, local gravitational collapse created stars and, later, planets.

The prelude to this story began with a major cosmological event: inflation. Between 10^-36 and 10^-34 seconds after the Big Bang, the physical scale of our universe doubled in size more than 50 times, so that by today, it is trillions of times larger than the 14 billion-light-year extent we can observe.

This photographer drove six hours from his home in order to find the perfect position for this event that would take place for less than a minute!

A new study suggests that the expansion of the universe may be an illusion — and that effect could offer clues about dark matter.

Now consider two tabletops, parallel to each other but not touching. The second tabletop is also infinite in two dimensions, and other kinds of creatures live there. Finally, imagine that a narrow tunnel connects the two spaces somewhere.

Without access to the tunnel, the creatures dwelling in each space believe they live in a single, infinite universe. This is especially true if the tunnel lies outside their cosmic horizon. They will never know that their universes are part of a larger structure, a two-dimensional multiverse. It is easy to imagine an infinite number of two-dimensional flat spaces stacked on top of one another, each connected to the next by a similar tunnel, and each tunnel inaccessible to any of the universes’ inhabitants.

The multiverse need not be so simple, either. Universes can be curved and finite, sprouting from an infinite mother universe. The sprouting universes may themselves be infinite. Think of bubbles being blown from a piece of bubble gum. Little bubbles will shrink back, while bigger ones might keep on growing. If a bubble starts growing in a heavily populated region of flat space, some of the inhabitants will be carried into it. Others will remain outside, horrified to see their friends sucked into oblivion. But most of the creatures in the growing bubble survive their ordeal and start to explore their new world. Generations pass. Their scientists measure the curvature of space and see that their universe is closed, like the surface of a sphere. Since the bubble kept on growing, the tunnel-like aperture to the original universe is well beyond their cosmic horizon. These creatures live in a closed, expanding universe, unaware of their connection to a flat, infinite space. Meanwhile, creatures in the original space saw the aperture to the bubble universe close more and more until it became too narrow to cross. All that is left, to them, is a scar in space marking the long-forgotten birthing event. The bubble universe is isolated from its mother universe.

Using the Spectrum–RG (SRG) spacecraft and two ground-based telescopes, Russian astronomers have observed X-ray sources in the eastern Galactic sky. The observational campaign resulted in the detection of 14 new active galactic nuclei. The findings were presented June 6 in the journal Astronomy Letters.

An active galactic nucleus (AGN) is a compact region at the center of a galaxy, more luminous than the surrounding galaxy light. AGNs are very energetic due either to the presence of a black hole or star formation activity at the core of the galaxy.

Astronomers generally divide AGNs into two groups based on emission line features. Type 1 AGNs show broad and narrow emission lines, while only narrow emission lines are present in Type 2 AGNs.

A new technique has been used to estimate the age of globular star cluster M92 at 13.8 billion years, plus or minus 0.75 billion years. This is an almost exact match for the estimated age of the Universe, albeit with wider error bars. Either this nearby collection of stars formed as soon as possible after the Big Bang, or we’ve been underestimating how old the Universe really is.

Globular clusters are, as the name suggests, near-spherical collections of tens of thousands of tightly packed stars sitting outside galaxies. In general, they are very old – but some are considerably older than others, and these attract the most interest from astronomers as they provide us with insight into the universe’s earliest days.

M92 is a favorite object for northern hemisphere amateur astronomers, being easily visible in binoculars, but to professionals it’s particularly significant as a candidate for the oldest globular cluster in our near vicinity. Indeed, as a forthcoming paper notes, M92 is often used as a benchmark against which we measure newly forming galaxies seen soon after the Big Bang.