MessageToEagle.com - Have you ever wondered what the Universe will look like for a future alien astronomer?
It will in fact be entirely different from what it is today.
One trillion years from now, an alien astronomer in our galaxy will have great difficulties figuring out how the universe began.
The Milky Way will have merged with the Andromeda galaxy to form the Milkomeda galaxy. Many of its stars, including our Sun, will have burned out.
The universe's ever-accelerating expansion will send all other galaxies rushing beyond our "cosmic horizon," sending them forever out of view.
It was Edwin Hubble who made the first observations in support of the Big Bang model.
He showed that galaxies are rushing away from each other due to the universe's expansion.
More recently, astronomers discovered a pervasive afterglow from the Big Bang, known as the cosmic microwave background,
left over from the universe's white-hot beginning.
The Universe's expansion will cause the cosmic microwave background to fade out, stretching the wavelength of CMB photons to become longer
than the visible universe.
Without the clues of the CMB and distant, receding galaxies, how will these far-future astronomers know the Big Bang happened?
According to Harvard theorist Avi Loeb, clever astronomers in 1 trillion C.E. could still infer the Big Bang and today's leading
cosmological theory, known as "lambda-cold dark matter" or LCDM. They will have to use the most distant light source available to
them - hypervelocity stars flung from the center of Milkomeda.
Artistic impression of the collision between Milky Way and Andromeda galaxy. Credit: Hubble Space Telescope, James Gitlin
"We used to think that observational cosmology wouldn't be feasible a trillion years from now," said Loeb, who directs the Institute
for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics. "Now we know this won't be the case. Hypervelocity stars
will allow Milkomeda residents to learn about the cosmic expansion and reconstruct the past."
About once every 100,000 years, a binary-star system wanders too close to the black hole at our galaxy's center and gets ripped apart.
One star falls into the black hole while the other is flung outward at a speed greater than 1 million miles per hour - fast enough to be
ejected from the galaxy entirely.
What the Universe will look like for a future alien astronomer? Credit: Hubble Space Telescope, James Gitlin
Finding these hypervelocity stars is more challenging than spotting a needle in a haystack, but future astronomers would have a good reason to hunt diligently.
Once they get far enough from Milkomeda's gravitational pull, these stars will get accelerated by the universe's expansion.
Astronomers could measure that acceleration with technologies more advanced than we have today. This would provide a different line of evidence
for an expanding universe, similar to Hubble's discovery but more difficult due to the very small effect being measured.
By studying stars within Milkomeda, they could infer when the galaxy formed. Combining that information with the hypervelocity star measurements,
they could calculate the age of the universe and key cosmological parameters like the value of the cosmological constant (the lambda in LCDM).
"Astronomers of the future won't have to take the Big Bang on faith. With careful measurements and clever analysis,
they can find the subtle evidence outlining the history of the universe," said Loeb.
So there is no doubt, that in a trillion years, when the universe is 100 times older than it is now, alien astronomers will have a very different view.
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MessageToEagle.com - Have you ever wondered what the Universe will look like for a future alien astronomer?
It is an exotic and distant object, which has a velocity of recession of approximately 270,000 kilometers per second (!) or - 91 percent of the
velocity of light itself.
The formation of stellar-mass black holes through the collapse of massive stars is well accepted. However,
it is not yet completely clear how the supermassive objects are formed.
The pulse timing of this object is considered unusual.
What kind of phenomenon is related to this object?
It is the first time this kind of phenomenon has been observed by astronomers.
An object obscured by dust, and buried in a two-star system enshrouded by dense gas, is not easy to find.
This alien intruder from another galaxy is in many ways different from other exoplanets observed by astronomers.
The 3C294, is one of the most distant galaxies recorded by Chandra, the most sophisticated X-ray observatory ever built.
The cluster 3C294 is even 40 percent farther (!) than the next most distant x-ray galaxy cluster.
Chandra focus on X-rays from high-energy regions of the Universe and see the invisible.
It is so sensitive that it can capture images of particles as they disappear into a black hole deep in outer space.