Jun 4, 2025 06:00 PM
Expansion of the universe: An end to the ‘Hubble Tension’?
https://www.centauri-dreams.org/2025/06/...e-tension/
EXCERPTS: Now we have new work that looks at the rate of expansion using data from the James Webb Space Telescope, doubling the sample of galaxies used to calibrate the supernovae results. The paper’s lead author, Wendy Freedman of the University of Chicago, argues that the JWST results resolve the Hubble tension. With Hubble data included in the analysis as well, Freedman calculates a Hubble value of 70.4 kilometers per second per megaparsec, plus or minus 3%. This result brings the supernovae results into statistical agreement with recent cosmic microwave background data showing 67.4, plus or minus 0.7%.
[...] A lack of agreement between the CMB findings and the supernovae data could have been pointing to interesting new physics, but according to this work, the Standard Model of the universe holds up. In a way, that’s too bad for using the discrepancy to probe into mysterious phenomena like dark energy and dark matter, but it seems we’ll have to be looking elsewhere for answers to their origin. Ahead for Freedman and team are new measurements of the Coma cluster that Freedman suggests could fully resolve the matter within years... (MORE - missing details)
What if the Big Bang wasn’t the beginning? Our research suggests it may have taken place inside a black hole
https://theconversation.com/what-if-the-...ole-258010
INTRO: The Big Bang is often described as the explosive birth of the universe – a singular moment when space, time and matter sprang into existence. But what if this was not the beginning at all? What if our universe emerged from something else – something more familiar and radical at the same time?
In a new paper, published in Physical Review D, my colleagues and I propose a striking alternative. Our calculations suggest the Big Bang was not the start of everything, but rather the outcome of a gravitational crunch or collapse that formed a very massive black hole – followed by a bounce inside it. [Black hole cosmology]
This idea, which we call the black hole universe, offers a radically different view of cosmic origins, yet it is grounded entirely in known physics and observations.
Today’s standard cosmological model, based on the Big Bang and cosmic inflation (the idea that the early universe rapidly blew up in size), has been remarkably successful in explaining the structure and evolution of the universe. But it comes at a price: it leaves some of the most fundamental questions unanswered... (MORE - details)
Discovery of giant planet orbiting tiny star challenges theories on planet formation
https://www.eurekalert.org/news-releases/1085419
INTRO: Star TOI-6894 is just like many in our galaxy, a small red dwarf, and only ~20% of the mass of our Sun. Like many small stars, it is not expected to provide suitable conditions for the formation and hosting of a large planet.
However, as published today in Nature Astronomy, an international team of astronomers have found the unmistakable signature of a giant planet, called TOI-6894b, orbiting this tiny star.
This system has been discovered as part of a large-scale investigation of TESS (Transiting Exoplanet Survey Satellite) data, looking for giant planets around low-mass stars, led by Dr. Edward Bryant, who completed this work at The University of Warwick and at UCL’s Mullard Space Science Laboratory.
Dr. Edward Bryant, Warwick Astrophysics Prize Fellow and first author said: “I was very excited by this discovery. I originally searched through TESS observations of more than 91,000 low-mass red-dwarf stars looking for giant planets.
“Then, using observations taken with one of the world’s largest telescopes, ESO’s VLT, I discovered TOI-6894b, a giant planet transiting the lowest mass star known to date to host such a planet. We did not expect planets like TOI-6894b to be able to form around stars this low-mass. This discovery will be a cornerstone for understanding the extremes of giant planet formation.”
The planet (TOI-6894b) is a low-density gas giant with a radius a little larger than Saturn’s but with only ~50% of Saturn’s mass. The star (TOI-6894) is the lowest mass star to have a transiting giant planet discovered to date and is just 60% the size of the next smallest star to host such a planet.
Dr. Daniel Bayliss, Associate Professor at The University of Warwick said: “Most stars in our Galaxy are actually small stars exactly like this, with low masses and previously thought to not be able to host gas giant planets. So, the fact that this star hosts a giant planet has big implications for the total number of giant planets we estimate exist in our Galaxy.” (MORE - details, no ads)
https://www.centauri-dreams.org/2025/06/...e-tension/
EXCERPTS: Now we have new work that looks at the rate of expansion using data from the James Webb Space Telescope, doubling the sample of galaxies used to calibrate the supernovae results. The paper’s lead author, Wendy Freedman of the University of Chicago, argues that the JWST results resolve the Hubble tension. With Hubble data included in the analysis as well, Freedman calculates a Hubble value of 70.4 kilometers per second per megaparsec, plus or minus 3%. This result brings the supernovae results into statistical agreement with recent cosmic microwave background data showing 67.4, plus or minus 0.7%.
[...] A lack of agreement between the CMB findings and the supernovae data could have been pointing to interesting new physics, but according to this work, the Standard Model of the universe holds up. In a way, that’s too bad for using the discrepancy to probe into mysterious phenomena like dark energy and dark matter, but it seems we’ll have to be looking elsewhere for answers to their origin. Ahead for Freedman and team are new measurements of the Coma cluster that Freedman suggests could fully resolve the matter within years... (MORE - missing details)
What if the Big Bang wasn’t the beginning? Our research suggests it may have taken place inside a black hole
https://theconversation.com/what-if-the-...ole-258010
INTRO: The Big Bang is often described as the explosive birth of the universe – a singular moment when space, time and matter sprang into existence. But what if this was not the beginning at all? What if our universe emerged from something else – something more familiar and radical at the same time?
In a new paper, published in Physical Review D, my colleagues and I propose a striking alternative. Our calculations suggest the Big Bang was not the start of everything, but rather the outcome of a gravitational crunch or collapse that formed a very massive black hole – followed by a bounce inside it. [Black hole cosmology]
This idea, which we call the black hole universe, offers a radically different view of cosmic origins, yet it is grounded entirely in known physics and observations.
Today’s standard cosmological model, based on the Big Bang and cosmic inflation (the idea that the early universe rapidly blew up in size), has been remarkably successful in explaining the structure and evolution of the universe. But it comes at a price: it leaves some of the most fundamental questions unanswered... (MORE - details)
Discovery of giant planet orbiting tiny star challenges theories on planet formation
https://www.eurekalert.org/news-releases/1085419
INTRO: Star TOI-6894 is just like many in our galaxy, a small red dwarf, and only ~20% of the mass of our Sun. Like many small stars, it is not expected to provide suitable conditions for the formation and hosting of a large planet.
However, as published today in Nature Astronomy, an international team of astronomers have found the unmistakable signature of a giant planet, called TOI-6894b, orbiting this tiny star.
This system has been discovered as part of a large-scale investigation of TESS (Transiting Exoplanet Survey Satellite) data, looking for giant planets around low-mass stars, led by Dr. Edward Bryant, who completed this work at The University of Warwick and at UCL’s Mullard Space Science Laboratory.
Dr. Edward Bryant, Warwick Astrophysics Prize Fellow and first author said: “I was very excited by this discovery. I originally searched through TESS observations of more than 91,000 low-mass red-dwarf stars looking for giant planets.
“Then, using observations taken with one of the world’s largest telescopes, ESO’s VLT, I discovered TOI-6894b, a giant planet transiting the lowest mass star known to date to host such a planet. We did not expect planets like TOI-6894b to be able to form around stars this low-mass. This discovery will be a cornerstone for understanding the extremes of giant planet formation.”
The planet (TOI-6894b) is a low-density gas giant with a radius a little larger than Saturn’s but with only ~50% of Saturn’s mass. The star (TOI-6894) is the lowest mass star to have a transiting giant planet discovered to date and is just 60% the size of the next smallest star to host such a planet.
Dr. Daniel Bayliss, Associate Professor at The University of Warwick said: “Most stars in our Galaxy are actually small stars exactly like this, with low masses and previously thought to not be able to host gas giant planets. So, the fact that this star hosts a giant planet has big implications for the total number of giant planets we estimate exist in our Galaxy.” (MORE - details, no ads)