Space News/UFO's Etc...(Discussion/Pics/Vids)

[ilan]

Does Stephen Hawking’s final theory tame the multiverse?
Deborah Byrd in HUMAN WORLD | SPACE | May 2, 2018

"I have never been a fan of the multiverse. If the scale of different universes in the multiverse is large or infinite the theory can’t be tested.”

Stephen Hawking said of his study: “We are not down to a single, unique universe, but our findings imply a significant reduction of the multiverse, to a much smaller range of possible universes.” Image via Eleanor Bentall/ Telegraph.co.uk.

Does Stephen Hawking’s last study – published May 2, 2018, in the peer-reviewed Journal of High Energy Physics – prove or disprove the existence of parallel worlds? No. It’s a theory, one of many ideas in modern cosmology, many of which lead to the multiverse concept, the idea that our universe of stars and galaxies is just one of many possible separate universes. Some physicists told media sources that Hawking’s final paper did:

... set out the groundbreaking mathematics needed for a spacecraft to find traces of multiple Big Bangs.

Other physicists disagreed, telling the media:

The paper makes no statements about observational tests. It’s … one of literally several thousand ideas for what might possibly have happened in the early universe.

In fact, the study has been commented on extensively, since it first appeared online in July 2017, in the preprint journal arXiv. Hawking and Thomas Hertog, a former student and frequent collaborator at Belgium’s Catholic University Leuven, posted an updated version of the study on arXiv on March 4, 2018, just 10 days before Hawking’s death on March 14 in Cambridge, England.

The study centers on the decades-long conflict between Albert Einstein’s general relativity theory (nature at very large scales, for example, how gravity works), and quantum mechanics (nature at very small scales; for example, the attempt to understand subatomic particles).

Hawking and Hertog’s latest study deals specifically with a subset of Big Bang theory, called eternal inflation. Most modern Big Bang theories incorporate the idea of an inflation, which calls for an exponential expansion of space in the universe’s first fraction of a second. Eternal inflation suggests that some pockets of space keep expanding exponentially forever, while some (like the one we inhabit) don’t.

If this theory is an accurate description of the cosmos, then we live in a multiverse consisting of many isolated bubble universes.

If it’s true, then our entire known cosmos of galaxies and stars exists inside a sort of bubble, but many other bubbles – forever unknowable – exist outside ours. Some might have laws of physics similar to (or even the same as) ours. Some would operate very differently. The University of Cambridge issued a statement about Hawking’s final study this week. It explained:

The observable part of our universe would then be just a hospitable pocket universe, a region in which inflation has ended and stars and galaxies formed.

Hawking said in one of his last interviews:

The usual theory of eternal inflation predicts that globally our universe is like an infinite fractal, with a mosaic of different pocket universes, separated by an inflating ocean. The local laws of physics and chemistry can differ from one pocket universe to another, which together would form a multiverse.

But I have never been a fan of the multiverse. If the scale of different universes in the multiverse is large or infinite the theory can’t be tested.

And indeed, in their new study, Hawking and Hertog say this account of eternal inflation as a theory of the Big Bang is wrong. Hertog said:

We predict that our universe, on the largest scales, is reasonably smooth and globally finite. So it is not a fractal structure.

Cambridge’s statement explained more and showed how Hawking and Hertog’s study incorporated some of the most far-out physics of our time:

The theory of eternal inflation that Hawking and Hertog put forward is based on string theory: a branch of theoretical physics that attempts to reconcile gravity and general relativity with quantum physics, in part by describing the fundamental constituents of the universe as tiny vibrating strings. Their approach uses the string theory concept of holography, which postulates that the universe is a large and complex hologram: physical reality in certain 3D spaces can be mathematically reduced to 2D projections on a surface.

Hawking and Hertog developed a variation of this concept of holography to project out the time dimension in eternal inflation. This enabled them to describe eternal inflation without having to rely on Einstein’s theory.

Hertog said:

When we trace the evolution of our universe backwards in time, at some point we arrive at the threshold of eternal inflation, where our familiar notion of time ceases to have any meaning.The new study harks back to Hawking’s earlier no boundary theory, which predicted that – if you go back in time to the beginning of the universe – the universe shrinks and closes off like a sphere.

The new study is a step away from the earlier work, Hertog explained, and he said:

Now we’re saying that there is a boundary in our past.

And so physics moves on …

In the film below, Stephen Hawking, James Hartle and Thomas Hertog explain their model of the early universe – The No Boundary Proposal – a model of the Big Bang that included quantum effects. These scientists say it explains some of the deepest mysteries of the cosmos such as, is there a multiverse? How is there an arrow of time? What really happened during the Big Bang?

__________________________________________

This new theory suggests there may be other (multiple) universes, but probably not as many as once believed, and they are most likely not that different from our own in terms of the physical laws that operate within them. - ilan

[Capt.Kangaroo]

Great read, still above my pay grade though....

[ilan]

Still working on the formatting...

I thought this one was pretty understandable. For sure, it is intriguing. And since it's his last piece of work, I gave it some due

[Capt.Kangaroo]

Still working on the formatting...

I thought this one was pretty understandable. For sure, it is intriguing. And since it's his last piece of work, I gave it some due

You do a great job in this Section, its even better than I hoped for since I asked Tinie to start it up at the old Beta site.
Thanks for all the great info....

[ilan]

My pleasure, Cap

[ilan]

What if aliens can't reach Earth because gravity traps them on their worlds?
Phys.Org, Cordis | May 4, 2018


Credit: Kateryna Kon, Shutterstock

The truth is out there. You want to believe. But you are becoming more and more frustrated because there's no conclusive evidence. All this time, the reason could be basic physics. A study submitted to the International Journal of Astrobiology suggests that aliens living on distant planets can't cruise the cosmos because of gravity.

Man has found numerous exoplanets in the hunt for alien worlds. Most are large planets like Jupiter, while some are the size of Earth or slightly smaller. Others fall somewhere in between and are called super-Earths. They're about 10 times larger than Earth.

If aliens are out there, why are they grounded?

Astronomers and astrophysicists believe that super-Earths could shelter alien life. If earthlings can build rockets and explore the universe, why can't extraterrestrials do the same? According to the findings, super-Earths have massive gravitational pulls. These keep alien spacecraft from generating enough thrust to escape the gravitational forces of their home planets. To launch the equivalent of an Apollo moon mission, a rocket on a super-Earth would need to have a mass of about 440 000 tonnes because of fuel requirements.

"On more-massive planets, spaceflight would be exponentially more expensive," study author Michael Hippke, an independent researcher affiliated with the Sonneberg Observatory in Germany, told Space.com. "Such civilizations would not have satellite TV, a moon mission or a Hubble Space Telescope."

Hippke examined how difficult it would be to blast off from a hypothetical super-Earth. He calculated the rocket sizes needed to escape a super-Earth that is 70 % wider than our planet and 10 times more massive. These are about the dimensions of the planet Kepler-20b, which lies some 950 light years from Earth. On this super-Earth, the escape velocity needed would be roughly 2.4 times greater than on our planet.

Speaking to the UK's 'Daily Mail', Hippke said: "Civilisations from super-Earths are much less likely to explore the stars. Instead, they would be to some extent arrested on their home planet and, for example, make more use of lasers or radio telescopes for interstellar communication instead of sending probes or spaceships."

Fuel – the great barrier to alien travel

The weight of the fuel that conventional rockets carry is another major challenge for aliens on a planet like Kepler-20b. This means that they would need to use rockets that don't depend on chemical fuel to get into space. According to the research, a potential solution is a nuclear-powered spacecraft to leave a planet more than 10 times Earth's mass.

But they're extraterrestrials, after all! Shouldn't they have some kind of alien technology to help them get off their planets? Until then, some of us will have a good excuse as to why we haven't seen UFOs cruising overhead.

[ilan]

Insight Mars is on its way
Eddie Irizarry in HUMAN WORLD | SPACE | May 5, 2018

The Insight Mars lander is due to set down on Mars’ surface in November, 2018.

The Insight Mars mission is on its way to the red planet, following a successful May 5, 2018, predawn liftoff from Space Launch Complex 3 at Vandenberg Air Force Base in California.

InSight‘s lander is due to set down on Mars’ surface in November 2018. InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) was the first planetary mission to launch from the U.S. West Coast.

The Atlas V rocket reached an initial parking orbit at an altitude of 115 miles (185 km) about 13 minutes after launch, when the rocket was about 1,200 miles (1,900 km) northwest of Isabella Island, Ecuador. It then passed over Tierra del Fuego and Antarctica. Then its trajectory continued to the north, passing close to India, and finally near Alaska, where the InSight spacecraft separated from the rocket to continue its journey to Mars.

[ilan]

New science from Jupiter
Eleanor Imster in SPACE | May 7, 2018

When the Juno spacecraft recently flew over the poles of Jupiter, researchers were astonished. This 5-minute video from NASA explores the latest discoveries.

NASA’s Juno mission launched on August 5, 2011, traveled 1.74 billion miles (2.8 billion km) and entered Jupiter’s orbit on July 4, 2016.

This new NASA ScienceCast video rounds up some of Juno’s coolest finds.

Juno’s mission is to measure Jupiter’s composition, gravity field, magnetic field, and polar magnetosphere. It’s also searching for clues about how the planet formed, including whether it has a rocky core; how much water there is within the deep atmosphere; and Jupiter’s deep winds, which can reach speeds up to 384 miles per hour (618 km per hour).

Earth will pass between Jupiter and the sun this week! That means we’re now in the middle of the best time of year to see the planet. Learn more – including how to spot Jupiter – at EarthSky’s Tonight page.

Bottom line: NASA video describes the newest science from the Juno mission to Jupiter.

[ilan]

Bright star Vega on May evenings
Deborah Byrd in TONIGHT | May 10, 2018

Tonight, look for the star Vega, the fifth brightest star in the sky. If you’re in the Northern Hemisphere, you’ll find this beautiful bluish star easily, simply by looking northeastward at mid-evening in May.

Try it! Just look northeast in mid-evening in May. You’ll see this bright bluish star shining above that horizon. From far south in the Southern Hemisphere, you can’t see this star until late at night in May because Vega is located so far north on the sky’s dome. Vega will reach its high point for the night around 3 to 4 hours after midnight, at which time people in the Southern Hemisphere can see this star in the northern sky. As seen from mid-northern latitudes, the star shines high overhead at this early morning hour.

Because it’s the brightest star in the constellation Lyra the Harp, Vega is sometimes called the Harp Star.

The constellation Lyra the Harp, with its brightest star Vega and other
interesting stars or objects within its boundaries.

Vega is a lovely star to come to know. When I was first learning the night sky, nearly 40 years ago, I spent hours, days, weeks, months poring over charts and books. So I sometimes came to know the names and whereabouts of certain stars before seeing them in the night sky. One soft May evening, I happened to glance toward the northeast. I was thrilled at the sight of Vega – gleaming, sapphire-blue – and surprisingly bright for being so low in the sky.

Like all stars, Vega rises some four minutes earlier each day as Earth moves around the sun. So Vega will ornament our evening sky throughout the summer and fall.

Although Vega is considered a late spring or summer star, it’s actually so far north on the sky’s dome that you can find it at some time during the night, nearly every night of the year at mid-northern latitudes.

Bottom line: It’s easy to identify the star Vega in the constellation Lyra at this time of year. Just look northeast in the evening for a bright, bluish star above the northeastern horizon.