Original Post from Inside Science
Signal hints at possible interactions between ordinary hydrogen and dark matter in the early universe, but some scientists remain skeptical.
(Inside Science) — After spending nearly two decades listening to the skies with radio telescopes, astronomers have finally detected a long-sought-after and subtle signal from the early universe. A group of scientists claim to have found a sign of radiation from the very first generation of stars, only about 180 million years after the Big Bang — just a blink of an eye to the cosmos.
“Other than the cosmic microwave background radiation, this is the earliest observation of any kind in the universe. Compare it to Hubble looking at the first galaxies at 400 million years old; we’re looking at a time roughly half that age,” said Judd Bowman, a cosmologist at Arizona State University in Tempe, Arizona and lead author of the research, published today in the journal Nature.
During an era known as the “cosmic dawn,” the first stars were forged from primordial hydrogen and helium gas. Their ultraviolet light reached free hydrogen gas in the surrounding regions, interacting with the atoms in a way that left a key signature in the radio spectrum from the afterglow of the Big Bang. Looking for signatures like this helps astronomers probe the early moments of the universe when it was first beginning to form its structure.
Artist’s rendering of how the first stars in the universe may have looked.
Image credits: N.R. Fuller, National Science Foundation
From Science News
When it comes to the dimensions of spacetime, what you see may be what you get.
Using observations from the collision of two neutron stars that made headlines in 2017 (SN: 11/11/17, p. 6), scientists found no evidence of gravity leaking into hidden dimensions. The number of observed large spatial dimensions — kilometer-scale or bigger — is still limited to the three we know and love, the researchers report January 24 at arXiv.org.
Just as insects floating on a pond may be unaware of what’s above or below the water’s surface, our 3-D world might be part of a higher-dimensional universe that we can’t directly observe. However, says astrophysicist David Spergel of Princeton University, a coauthor of the new study, “gravity might be able to explore those other dimensions.”
Such extra dimensions might explain some conundrums in physics, such as the existence of dark matter (an as-yet-unidentified source of mass in the universe) and dark energy (which causes the universe’s expansion rate to accelerate), says coauthor Daniel Holz, an astrophysicist at the University of Chicago. “That’s why people get excited about these modifications.”
To look for any hint of leaking gravity, scientists turned to the light and gravitational waves emitted in the neutron star smashup detected on August 17, 2017
This is one of the best explanations for Feynman’s Infinite Quantum Paths thanks to PBS Space Time
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Physics Girl nails the birth of Quantum Mechanics from mistakes made by physicists attempting to solve other problems.
Original article from SCIENCE ALERT
Physicists just discovered a totally new form of light – ScienceAlert<img src=”https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=fnMIk1a4eFf2Io” style=”display:none” height=”1″ width=”1″ alt=””/><img height=”1″ width=”1″ alt=”” style=”display:none” src=”https://www.facebook.com/tr?id=1732289343662988&amp;ev=PixelInitialized”/>
Physicists have just discovered a new form of light that doesn’t follow our existing rules of angular momentum, and it could shake up our understanding of the electromagnetic radiation and lead to faster, more secure optical communication.
Because of how well-studied and, well, everywhere, light is, you might assume that we’ve pretty much learnt all there is to know about it. But just last year, researchers identified a fundamental new property of light, and now a team of Irish scientists has shown that light can take on unexpected new forms.
One of the ways we measure a beam of light is through its angular momentum – a constant quantity that measures how much light is rotating. And until now, it was thought that for all forms of light, the angular momentum would be a whole number (known as an integer) multiple of Planck’s constant – a physical constant that sets the scale of quantum effects.
But researchers led by Trinity College Dublin have now demonstrated that a new form of light exists, where the angular momentum is only half of this value.
“What I think is so exciting about this result is that even this fundamental property of light, that physicists have always thought was fixed, can be changed,” said lead researcher Paul Eastham.
Let’s back up for a second here and explain what all that means. READ MORE…
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