They are known as ultra-fast outflows (UFOs), powerful space winds emitted by the supermassive black holes (SMBHs) at the center of active galactic nuclei (AGNs) – aka. “quasars.” These winds (with a fun name!) move close to the speed of light (relativistic speeds) and regulate the behavior of SMBHs during their active phase.
These gas emissions are believed to fuel the process of star formation in galaxies but are not yet well understood. Astronomers are interested in learning more about them to improve our understanding of what governs galactic evolution.
NASA recently made an extraordinary discovery of a large thermonuclear explosion in space, caused by a pulsar, which is the remains of a star that did not explode to form a black hole. The National Aeronautics and Space Administration was able to detect the explosion thanks to the strong beam of X-rays sent out by the burst, which was picked up by the agency’s orbiting observatory NICER.
This discovery serves as a potent reminder of the dangers that lurk in space. According to a study published in The Astrophysical Journal Letters in August, the burst released as much energy as the sun does in ten days in just twenty seconds.
The leader of the study and astrophysicist, Peter Bult, said in a statement from NASA, “This burst was great.” Bult also added that the study revealed a two-step change in brightness that they believe was caused by the ejection of separate layers from the pulsar’s surface. These features provide significant information to understand how these events work.
Physicists have long puzzled over why there is more matter in the Universe than its flipped twin, antimatter. Without this imbalance, the two types of material would have canceled out, leaving nothing but a boring glow in the vast emptiness of space.
Somehow, at some point, something changed in the way the Universe works on a fundamental level, favoring the mirrored state – or parity – of one kind of ‘stuff’ over the other.
Scientists have sought clues to this critical moment in the remnants of the Big Bang, including the cosmic microwave background and gravitational waves, without much luck.
A recent discovery made by astronomers operating the Hubble Space Telescope has revealed the presence of a black hole at the center of a dwarf galaxy that actually creates stars instead of consuming them. This revelation has challenged the common perception that black holes only destroy matter.
The method by which stars are formed in this particular dwarf galaxy, named Henize 2–10, is fundamentally different from how stars are formed in larger galaxies. Astronomers have observed that gas moves around the black hole before merging with a core of dense gas present in the galaxy.
The Hubble spectroscopy revealed that the outflow of this gas was traveling at a rate of a million miles per hour, which eventually collided with the dense gas present in the galaxy. The outflow created clusters of newly born stars on its path.
There is a lot of speculation about the end of the universe. Humans love a good ending after all. We know that the universe started with the Big Bang and it has been going for almost 14 billion years. But how the curtain call of the cosmos occurs is not certain yet. There are, of course, hypothetical scenarios: the universe might continue to expand and cool down until it reaches absolute zero, or it might collapse back onto itself in the so-called Big Crunch. Among the alternatives to these two leading theories is “vacuum decay”, and it is spectacular – in an end-of-everything kind of way.
While the heat death hypothesis has the end slowly coming and the Big Crunch sees a reversal of the universe’s expansion at some point in the future, the vacuum decay requires that one spot of the universe suddenly transforms into something else. And that would be very bad news.
There is a field that spreads across the universe called the Higgs field. Interaction between this field and particles is what gives the particles mass. A quantum field is said to be in its vacuum state if it can’t lose any energy but we do not know if that’s true for the Higgs field, so it’s possible that the field is in a false vacuum at some point in the future. Picture the energy like a mountain. The lowest possible energy is a valley but as the field rolled down the slopes it might have encountered a small valley on the side of that mountain and got stuck there.
“It’s an interesting question to ask: Are there things other than a black hole” that “will give you a hint about what new physics could look like?” added Bah. “But before you get there, you need to know how to tell whether you have a black hole or not, and to do that you have some prototype examples of things that are not black holes to be able to compare.”
Black holes are among the most fascinating and puzzling objects ever observed in our universe. These massive compact entities have so much gravitational power that nothing, not even light, can escape beyond their borders, known as the event horizon. Scientists have imaged black holes with the Event Horizon Telescope and have captured the ripples that these objects make in spacetime, which are called gravitational waves.
What happened before the Big Bang? In two of our previous films we examined cyclic cosmologies and time travel universe models. Specially, the Gott and Li Model https://www.youtube.com/watch?v=79LciHWV4Qs) and Penrose’s Conformal Cyclic Cosmology https://www.youtube.com/watch?v=FVDJJVoTx7s). Recently Beth Gould and Niayesh Afshordi of the Perimeter Institute for Theoretical Physics have fused these two models together to create a startling new vision of the universe. In this film they explain their new proposal, known as Periodic Time Cosmology.
0:00 Introduction. 0:45 NIayesh’s story. 1:15 Beth’s story. 2:25 relativity. 3:26 Gott & Li model. 6:23 origins of the PTC model. 8:17 PTC periodic time cosmology. 10:55 Penrose cyclic model. 13:01 Sir Roger Penrose. 14:19 CCC and PTC 15:45 conformal rescaling and the CMB 17:28 assumptions. 18:41 why a time loop? 20:11 empirical test. 23:96 predcitions. 26:19 inflation vs PTC 30:22 gravitational waves. 31:40 cycles and the 2nd law. 32:54 paradoxes. 34:08 causality. 35:17 immortality in a cyclic universe. 38:02 eternal return. 39:21 quantum gravity. 39:57 conclusion.
Elizabeth Gould has asked to make this clarification in the written text ” “Despite the availability of infinite time in the periodic time model, this doesn’t lead to thermalization in a typical time-evolution scenario, and therefore doesn’t, strictly speaking, solve the problem related to thermalization in the power spectrum. The reason for this is that, unlike bounce models with a net expansion each cycle, our model has an effective contraction during the conformal phases. Periodic time, therefore, has a unique character in which it reuses the power spectrum from the previous cycles, which is confined to a given form due to the constraints of the system, rather than removing the old power spectrum and needing to produce a new one.”
What happens if dark-matter particles are produced inside a jet of Standard-Model particles? This leads to a novel detector signature known as semi-visible jets! The ATLAS Collaboration has come up with the first search for semi-visible jets, looking for them in a general production mode where two protons interact by exchanging an intermediate particle, which is then converted into two jets.
The elusive nature of dark matter remains one of the biggest mysteries in particle physics. Most of the searches have so far looked for events where a “weakly interacting” dark-matter particle is produced alongside a known Standard-Model particle. Since the dark-matter particle cannot be seen by the ATLAS detector, researchers look for an imbalance of transverse momentum (or “missing energy”).
