Astronomy & Space Exploration

Bert_ said:
I understand the philosophical thought process but science requires specific accuracy. If it didn't then science wouldn't exist.
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You understand but I don't know your opinion, maybe it's an impossible question because we don't know. Sometimes it's fun to imagine what would happen. Sometimes
 
Several times had been pointed out here and I like a lot this theory. The universe is so vast that it is impossible probabilistically speaking that there is no life in other parts of the universe. Also, probabilistically speaking is very likely that there are civilizations with the same/superior level of intelligence but as pointed out, is so vast that communication might not be possible

But the point that i like to go back is that not only the universe is vast but time since the big bang is vast too, so intelligent life capable to communicate with other lifeforms might sprout and die off way before or after another one appears, disappears. So is the combination of space and time that might not allow connection with different civilizations
 
4bars said:
Several times had been pointed out here and I like a lot this theory. The universe is so vast that it is impossible probabilistically speaking that there is no life in other parts of the universe. Also, probabilistically speaking is very likely that there are civilizations with the same/superior level of intelligence but as pointed out, is so vast that communication might not be possible

But the point that i like to go back is that not only the universe is vast but time since the big bang is vast too, so intelligent life capable to communicate with other lifeforms might sprout and die off way before or after another one appears, disappears. So is the combination of space and time that might not allow connection with different civilizations
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Good post and I agree with all of this.
Yes it is possible that there could be other civilisations somewhere out there in the universe.
But the vastness of space-time means that both communication and phasing of matching civilisations means we may never know.
 
Buster15 said:
Good post and I agree with all of this.
Yes it is possible that there could be other civilisations somewhere out there in the universe.
But the vastness of space-time means that both communication and phasing of matching civilisations means we may never know.
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And that makes even crazy that I fell in love with my partner. All this space and time... Happy valentines still in canada
 
Counterfactual said:
James Webb telescope finds ancient galaxy larger than our Milky Way, and it's threatening to upend cosmology

Astronomers believe the first galaxies formed around giant halos of dark matter. But a newly discovered galaxy dating to roughly 13 billion years ago mysteriously appeared long before that process should have occurred.

==
Any ideas, people? There seems to be a massive amount of hand-waving going on, which usually means scientists are baffled.
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Dark Matter simply is something that has never been proven but used (and tuned) as an explanation for a lot of observed structures in the universe. Probably we will get new iterations of Dark Matter, String Theory, other theories like MOND to explain the new discovery. There are still lots of open questions in that area.
 
stefan92 said:
Dark Matter simply is something that has never been proven but used (and tuned) as an explanation for a lot of observed structures in the universe. Probably we will get new iterations of Dark Matter, String Theory, other theories like MOND to explain the new discovery. There are still lots of open questions in that area.
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Dark Matter is believed to exist but has not interacted with any of the Fundamental Forces and hence has not been detected.
But it is believed to exist because without it, the Universe should not behave as it is doing. There is nothing like enough conventional matter to cause the Universe to keep expanding.
 
Buster15 said:
Dark Matter is believed to exist but has not interacted with any of the Fundamental Forces and hence has not been detected.
But it is believed to exist because without it, the Universe should not behave as it is doing. There is nothing like enough conventional matter to cause the Universe to keep expanding.
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Dark energy and dark matter explain different things. The former is the one theorised as responsible for accelerating the universe's expansion, the latter exists as an explanation of gravitational anomalies at the galactic scale and above. Among other things there's a shortfall in the amount of observable matter needed to account for how galaxies interact and to explain how they manage to retain their extremities even while undergoing rapid rotation. Dark matter is invoked as a convenient way of making up for this shortfall and ensuring the sums work.

 
Buster15 said:
Dark Matter is believed to exist but has not interacted with any of the Fundamental Forces and hence has not been detected.
But it is believed to exist because without it, the Universe should not behave as it is doing. There is nothing like enough conventional matter to cause the Universe to keep expanding.
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Small nitpick: depending on the theoretical candidate under consideration (and the hypothesized class of particle if applicable), “Dark Matter” could interact with the fundamental forces.

The Axion (a pseudoscalar boson) is one such theoretical candidate for cold dark matter, and they interact with all of the fundamental forces (at least weakly — this weak part complicates direct detection processes, rather than non-interaction).

Relevant arXiv submission: Axion Dark Matter: What is it and Why Now? By Francesca Chadha-Day, John Ellis, David J. E. Marsh.

Others, like Weakly Interacting Massive Particles (ratio of these super-symmetric particles to baryonic matter would be roughly 5:1), interact with only the weakest fundamental forces (which excludes the strong force and electromagnetism).

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And so on...
 
Ekkie Thump said:
Dark energy and dark matter explain different things. The former is the one theorised as responsible for accelerating the universe's expansion, the latter exists as an explanation of gravitational anomalies at the galactic scale and above. Among other things there's a shortfall in the amount of observable matter needed to account for how galaxies interact and to explain how they manage to retain their extremities even while undergoing rapid rotation. Dark matter is invoked as a convenient way of making up for this shortfall and ensuring the sums work.

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Thank you for this. Much appreciated.
 
Invictus said:
Small nitpick: depending on the theoretical candidate under consideration (and the hypothesized class of particle if applicable), “Dark Matter” could interact with the fundamental forces.

The Axion (a pseudoscalar boson) is one such theoretical candidate for cold dark matter, and they interact with all of the fundamental forces (at least weakly — this weak part complicates direct detection processes, rather than non-interaction).

Relevant arXiv submission: Axion Dark Matter: What is it and Why Now? By Francesca Chadha-Day, John Ellis, David J. E. Marsh.

Others, like Weakly Interacting Massive Particles (ratio of these super-symmetric particles to baryonic matter would be roughly 5:1), interact with only the weakest fundamental forces (which excludes the strong force and electromagnetism).

i7AFpKh.jpeg


And so on...
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That is very interesting. It differs from my understanding and so I have definitely learnt something from this. Thank you.
 

The Voyagers have enough electrical power and thruster fuel to keep its current suite of science instruments on until at least 2025. By that time, Voyager 1 will be about 13.8 billion miles (22.1 billion kilometers) from the Sun and Voyager 2 will be 11.4 billion miles (18.4 billion kilometers) away.
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Invictus said:
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Its almost pointless trying to communicate with them at this stage given that they are about to lose power and the morsels of data that reach earth aren't likely to reveal anything substantial. If they last 50 years total that would've been a great return on the initial effort in the 70s.
 
Voyager 1 spacecraft is currently the farthest human-made object from Earth and travels roughly one million miles a day. At its current speed, it would take Voyager 1 approximately 300 years to reach the Oort Cloud and another 30,000 years to reach its edge. Even if you were to travel at the speed of light, it would take about one month to reach the Oort Cloud and over one year to reach its edge. https://www.worldatlas.com/space/oort-cloud.html

It would take 73,000 years for it to reach Proxima Centauri.
 
giggs-beckham said:
Voyager 1 spacecraft is currently the farthest human-made object from Earth and travels roughly one million miles a day. At its current speed, it would take Voyager 1 approximately 300 years to reach the Oort Cloud and another 30,000 years to reach its edge. Even if you were to travel at the speed of light, it would take about one month to reach the Oort Cloud and over one year to reach its edge. https://www.worldatlas.com/space/oort-cloud.html

It would take 73,000 years for it to reach Proxima Centauri.
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To put that even further into context, the Oort cloud is considered the edge of our solar system so the end of our suns influence. I'll never quite understand the scale of space.
 
Balljy said:
To put that even further into context, the Oort cloud is considered the edge of our solar system so the end of our suns influence. I'll never quite understand the scale of space.
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The Ort Cloud is so big - and a lot deeper than i thought - 1 light year in radius. We think that Ort clouds of stars overlap due to their scale
 
The outer edge of the Ort Cloud as you say is the edge of our solar system, (albeit already interstellar space) if that distance we're 1mm then the diameter of the Milky way would be 100 meters.
And the observable universe would be 93,000 kilometres in diameter.
(Hastily calculated)

Or 1mm as 1 light year is 2.3 times around the earth.
 
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Nature Communications: Deep-sea hiatus record reveals orbital pacing by 2.4 Myr eccentricity grand cycles.

The gravitational tug of Mars may be strong enough to stir up Earth’s ocean, shifting its sediments as part of a 2.4-million-year climate cycle, researchers claim. It has long been accepted that wobbles in Earth’s orbit around the sun influence the planet’s climate, with these Milankovitch cycles operating on periods measured in thousands of years. Now, Adriana Dutkiewicz at the University of Sydney and her colleagues say they have found a 2.4-million-year “Grand Cycle”, which they believe is driven by Mars and has had dramatic impacts on currents in Earth’s oceans for at least 40 million years.

The evidence for this cycle comes from almost 300 deep-sea drill cores that reveal unexpected variation in the deposition of ocean sediment. During periods of stable ocean currents, oceanographers expect sediment to settle in steady layers, but unusual currents and eddies can see it accumulate elsewhere. According to the team, absences or hiatuses in the sediment deposition record line up with times when Mars’s gravity exerts maximum force on Earth, subtly impacting our planet’s orbital stability. This changes solar radiation levels and climate, manifesting as stronger currents and eddies in the oceans.

Team member Dietmar Müller, also at the University of Sydney, acknowledges that the distance between Earth and Mars is so vast that it is hard to conceive of any significant gravitational force being exerted. “But there are so many feedbacks that can amplify even subtle changes,” he says. “Mars’s impact on Earth’s climate is akin to a butterfly effect.”

Benjamin Mills at the University of Leeds, UK, says the drill cores provide more evidence for the existence of “megacycles” in global environmental change. “Many of us have seen these multi-million-year cycles in various different geological, geochemical and biological records – including during the famous explosion of animal life in the Cambrian Period,” he says. “This paper helps cement these ideas as key parts of environmental change.”

But Matthew England at the University of New South Wales in Sydney says that while he welcomes the work and thinks it adds to an understanding of climate cycles at a geological scale, he isn’t convinced by the paper’s conclusions. “I’m sceptical of the link to Mars, given its gravitational pull on Earth is so weak – at only about one one-millionth of that of the sun,” he says. “Even Jupiter has a stronger gravitational field for Earth.” England also points out that even if Mars is having an influence, it is nothing compared with human-driven climate change. “Greenhouse gas forcing is like a sledgehammer in comparison, so this has no bearing on present-day climate, where we are seeing melting ice sheets reduce the ocean overturning circulation.”
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MrMarcello said:
I find it amazing how celestial bodies can be millions of miles apart and have such gravitational affect on others.
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What I find amazing is that 2 galaxies can merge into each other and there would be few, if any collisions due to the great distances between stuff
 
Big Andy said:
What I find amazing is that 2 galaxies can merge into each other and there would be few, if any collisions due to the great distances between stuff
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Its because the space between objects is far more vast than the objects themselves. I found this short Nasa video on distances within the Milky Way pretty useful as to why collisions between star or planet sized objects will be extremely rare during the merger.

 
nimic said:
I think it's neat that when the Milky Way and Andromeda collide it's going to cause renewed star formation, which neither of them are really doing anymore.
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Going to be such a horrible turn of events for future civilizations, though; quintissential short term gain but long term pain scenario. :(

So much matter and energy (which are increasingly going to be in short supply) will be expended and wasted, instead of being ripe for harvest and repurposing (by life that exists at the time) in a sustainable manner...
  • With the possible creation of an inordinate amount of giant stars (which have paltry lifespans).
  • With the elevated accretionary appetite of (M31* + Sagittarius A*) and the kinetic processes preceding that merger. You might even get a quasar for a while = more precious matter and energy wasted.
  • Lots of stuff (again, valuable matter and energy) being ejected into intergalactic space due to gravitational interactions.
And so forth. Honestly, go away Andromeda (just not too far away, stay right where you are in relative terms, in perpetuity), Milky Way-ians (what's the appropriate demonym?) don't want to conglomerate with you. And same goes for the Local Group, the true harbinger of the “end times” — shooo-shooo!
 
Invictus said:
Going to be such a horrible turn of events for future civilizations, though; quintissential short term gain but long term pain scenario. :(

So much matter and energy (which are increasingly going to be in short supply) will be expended and wasted, instead of being ripe for harvest and repurposing (by life that exists at the time) in a sustainable manner...
  • With the possible creation of an inordinate amount of giant stars (which have paltry lifespans).
  • With the elevated accretionary appetite of (M31* + Sagittarius A*) and the kinetic processes preceding that merger. You might even get a quasar for a while = more precious matter and energy wasted.
  • Lots of stuff (again, valuable matter and energy) being ejected into intergalactic space due to gravitational interactions.
And so forth. Honestly, go away Andromeda (just not too far away, stay right where you are in relative terms, in perpetuity), Milky Way-ians (what's the appropriate demonym?) don't want to conglomerate with you. And same goes for the Local Group, the true harbinger of the “end times” — shooo-shooo!
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Yeah I guess, but ultimately if a civilization is at the point where they need to worry about - and can handle - that kind of cosmic energy demand, there are going to plenty of red dwarfs around to exploit, surely?
 
nimic said:
Yeah I guess, but ultimately if a civilization is at the point where they need to worry about - and can handle - that kind of cosmic energy demand, there are going to plenty of red dwarfs around to exploit, surely?
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Yes! And when all is said and done, they could huddle up and hold on for dear life around blacks holes too. But still, so much matter and energy being prematurely wasted (as well as the brutal inevitability of it all) is quite disheartening.
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Invictus said:
Yes! And when all is said and done, they could huddle up and hold on for dear life around blacks holes too. But still, so much matter and energy being prematurely wasted (as well as the brutal inevitability of it all) is quite disheartening.
D2S4w1r.gif
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That's one of my favourite things ever. I admit 100% of my knowledge about it comes from this Kurzgesagt video:

 
Big Andy said:
did they land it upright or did it have a Rapid Unscheduled Dissassembly?
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The latter (although unfortunately no pictures of it that I've found), but well back into the atmosphere. They also managed to test the payload doors and transfer fuel across tanks to mimic refueling in orbit. I think they've already got the next 4 iterations ready so it'll probably be some time this year when it gets to landing stage.
 
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Largest-Ever Map of Universe’s Active Supermassive Black Holes Released

Astronomers have charted the largest-ever volume of the universe with a new map of active supermassive black holes living at the centers of galaxies. Called quasars, the gas-gobbling black holes are, ironically, some of the universe’s brightest objects.

The new map logs the location of about 1.3 million quasars in space and time, the furthest of which shone bright when the universe was only 1.5 billion years old. (For comparison, the universe is now 13.7 billion years old.)

“This quasar catalog is different from all previous catalogs in that it gives us a three-dimensional map of the largest-ever volume of the universe,” says map co-creator David Hogg, a senior research scientist at the Flatiron Institute’s Center for Computational Astrophysics in New York City and a professor of physics and data science at New York University. “It isn’t the catalog with the most quasars, and it isn’t the catalog with the best-quality measurements of quasars, but it is the catalog with the largest total volume of the universe mapped.”
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The Astrophysical Journal: Quaia, the Gaia-unWISE Quasar Catalog, an All-sky Spectroscopic Quasar Sample
 
Earth just experienced a severe g4 geomagnetic storm. Here's what that means – and what you can expect.

The geomagnetic storm scale ranges from G1 to G5. At the lowest end is G1, described as minor storms that can lead to aurora being visible in Maine and Michigan’s Upper Peninsula. A G5 storm, described as extreme, could send the northern lights as far south as Florida and southern Texas.

https://www.cbsnews.com/news/earth-geomagnetic-storm-what-that-means-what-you-can-expect/
 
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