Sep 29, 2021 09:28 PM
(This post was last modified: Sep 29, 2021 09:49 PM by C C.)
Can we see farther back in space than we can in time?
https://bigthink.com/starts-with-a-bang/...pace-time/
INTRO: No matter where you look in the universe, in any direction, your line of sight will eventually run into some type of matter or radiation. The Earth is embedded in the solar system, with planets, moons, rocky and icy bodies, dust, and plasma particles permeating our environment. Beyond our own backyard are stars, gas, and dust strewn throughout the Milky Way, and at even greater cosmic distances are galaxies, quasars, and the matter in the intergalactic medium. If you somehow manage to pick a line of sight that doesn’t run into any of those, you’ll still encounter something: the cosmic microwave background, which is thought to be the leftover radiation from the early stages of the hot Big Bang.
And yet, no matter what we observe in any direction, two properties will correspond to whatever object we see:
But that isn’t true at all — and the expanding universe is to blame... (MORE)
A fast-moving star could be as good as a spaceship
https://www.supercluster.com/editorial/a...spaceship/
EXCERPTS: : Forget building spaceships. You can keep your Millennium Falcon, Jupiter 2, and USS Enterprise. Star Hitchhiking is the quickest way to see the cosmos. “A fast-moving star is as good as a spaceship,” says Jonathan Carroll-Nellenback, an astronomer at the University of Rochester.
The idea is simple. Allow yourself to be captured by the gravity of a passing star system as it draws near, and allow its motion through space to carry you to new systems. Maybe you’ll disembark at one of those systems, and set up your settlement on some strange new world. Then, eventually, another star will pass close by, and you’ll catch a ride to somewhere new. And so on.
Carroll-Nellenback has developed a computer simulation that shows how hitching rides with stars would help a space-faring civilization settle large chunks of the galaxy.
It begins with a civilization in the boondocks of the galaxy’s spiral arms, just beginning to reach out into the Universe. The civilization settles a few of its nearest star systems, a bit like if Earth-based humans settled on planets orbiting Proxima Centauri or Wolf 359. Then, a faster-moving star comes by, and the civilization quickly hops into orbit, riding through the galaxy, encountering more and more star systems to settle.
Supercluster
“This fast mover comes through and picks up life,” says Carroll-Nellenback. Eventually, when the expanding wavefront reaches the center of the galaxy, “it just explodes with settlements because the distances between the stars is so small in the center, that the colonizing wavefront grows at the fastest rate possible.”
This is another reason why the Search for Extraterrestrial Intelligence (SETI) should focus its efforts towards the center of our Milky Way Galaxy, and the centers of other galaxies, too. The simulation “shows the pattern of interstellar expansion for any species, no matter how much energy it uses,” says Jason Wright, a professor of astrophysics and director of the Penn State Extraterrestrial Intelligence Center at Penn State University.
[...] The Sun, for example, completes one orbit of the Milky Way every 220 million years. Proxima Centauri is currently the closest star to the Sun, at a distance of 4.2 light-years, but it hasn’t always been the closest, and will not be the closest in the future. For example, 70,000 years ago a red dwarf called Scholz’s Star passed within 1.9 light-years of the Sun, skirting the outer regions of the Oort Cloud.
If there had been space-faring humans alive 70,000 years ago, we might have hitched a ride on Scholz’s Star. Today, Scholz’s Star is 22 light-years away... (MORE)
https://bigthink.com/starts-with-a-bang/...pace-time/
INTRO: No matter where you look in the universe, in any direction, your line of sight will eventually run into some type of matter or radiation. The Earth is embedded in the solar system, with planets, moons, rocky and icy bodies, dust, and plasma particles permeating our environment. Beyond our own backyard are stars, gas, and dust strewn throughout the Milky Way, and at even greater cosmic distances are galaxies, quasars, and the matter in the intergalactic medium. If you somehow manage to pick a line of sight that doesn’t run into any of those, you’ll still encounter something: the cosmic microwave background, which is thought to be the leftover radiation from the early stages of the hot Big Bang.
And yet, no matter what we observe in any direction, two properties will correspond to whatever object we see:
- We are seeing the object not as it is today, but as it was a finite amount of time ago: when it emitted the light that’s now striking our eyes.
- That object is currently a specific distance away from us; if we could somehow “freeze” time and measure the distance between ourselves and that object, we’d get a certain value.
But that isn’t true at all — and the expanding universe is to blame... (MORE)
A fast-moving star could be as good as a spaceship
https://www.supercluster.com/editorial/a...spaceship/
EXCERPTS: : Forget building spaceships. You can keep your Millennium Falcon, Jupiter 2, and USS Enterprise. Star Hitchhiking is the quickest way to see the cosmos. “A fast-moving star is as good as a spaceship,” says Jonathan Carroll-Nellenback, an astronomer at the University of Rochester.
The idea is simple. Allow yourself to be captured by the gravity of a passing star system as it draws near, and allow its motion through space to carry you to new systems. Maybe you’ll disembark at one of those systems, and set up your settlement on some strange new world. Then, eventually, another star will pass close by, and you’ll catch a ride to somewhere new. And so on.
Carroll-Nellenback has developed a computer simulation that shows how hitching rides with stars would help a space-faring civilization settle large chunks of the galaxy.
It begins with a civilization in the boondocks of the galaxy’s spiral arms, just beginning to reach out into the Universe. The civilization settles a few of its nearest star systems, a bit like if Earth-based humans settled on planets orbiting Proxima Centauri or Wolf 359. Then, a faster-moving star comes by, and the civilization quickly hops into orbit, riding through the galaxy, encountering more and more star systems to settle.
Supercluster
“This fast mover comes through and picks up life,” says Carroll-Nellenback. Eventually, when the expanding wavefront reaches the center of the galaxy, “it just explodes with settlements because the distances between the stars is so small in the center, that the colonizing wavefront grows at the fastest rate possible.”
This is another reason why the Search for Extraterrestrial Intelligence (SETI) should focus its efforts towards the center of our Milky Way Galaxy, and the centers of other galaxies, too. The simulation “shows the pattern of interstellar expansion for any species, no matter how much energy it uses,” says Jason Wright, a professor of astrophysics and director of the Penn State Extraterrestrial Intelligence Center at Penn State University.
[...] The Sun, for example, completes one orbit of the Milky Way every 220 million years. Proxima Centauri is currently the closest star to the Sun, at a distance of 4.2 light-years, but it hasn’t always been the closest, and will not be the closest in the future. For example, 70,000 years ago a red dwarf called Scholz’s Star passed within 1.9 light-years of the Sun, skirting the outer regions of the Oort Cloud.
If there had been space-faring humans alive 70,000 years ago, we might have hitched a ride on Scholz’s Star. Today, Scholz’s Star is 22 light-years away... (MORE)