Astronomy and Cosmology

Hello! So, I've been listening to a lot of talks about alien life and the Fermi Paradox. It made me think; space is very very big. Is it just possible that the size of the galaxy is so vast that we just haven't had enough time to see any intelligent life? The galaxy is almost 53,000 light years across. That's quite a distance. Assuming Aplha Centauri isn't populated by space faring life, considering we see it 4 ish years in the past. Is that a valid argument? Thanks for your time! EDIT: I posted this twice by accident! My apologies.

I know that it was a very very very small and dense point... but what it contained? Where there any kind of a very small particles moving inside? Or was it all "frozen"? If there where moving particles (of any kind) inside the singularity point, then it means that there was also time inside, no? Just trying to understand.

Hi, Forbes just published an article about the Habitable Exoplanet Hunting Project: http://www.forbes.com/sites/jamiecartereurope/2019/11/25/inside-the-247-search-for-another-habitable-planet-within-100-light-years-of-earth/#149fbf103442 I hope you find it interesting! We welcome any type of observatory to join us. Cheers!

As some of you probably know, the Square Kilometre Array will become the biggest radio telescope on Earth, with a collecting area of 1 square kilometre. The construction will start in 2021 and the first light is expected to take place in 2027. It will cover the frequencies from 50 MHz to 15 Ghz. But what I wanted to share with you guys is a new study about how far the SKA can 'listen'. A recent study points out that the SKA could detect extraterrestrial airport radars 200 light years away. SPAM DELETED What do you guys think?

Why can't the Sun form a black? , because it can collapse too.

Do we have evidence that this expansion /inflation was/is entirely the same wherever we look in the Universe? On the large scale, I imagine as locally (on small scales) we don't see it ,do we? I am just wondering if there is a connection between relative motion and inflation or whether these are two entirely unrelated phenomena.(they do seem awfully similar on the face of it) Is inflation kind of like a background where relative motion does its own thing ? Did inflation come early on and relative motion later on ? Did the former "bleed into " the latter in any sense?

So, based on what I read, pulsar winds can move at speeds near that of light. Now, we all know with relativistic speeds, mass increases as it gets closer to light. Does that make such winds strong? If so, how strong are they? Do I need to add any more details? If so, what kind of details?

Here is the scenario:

In October 2012, astronomers announced the discovery of an exoplanet orbiting the star Alpha Centauri B. However, three years later, they concluded that it probably doesn’t exist. In 2013, astronomers also detected another possible exoplanet, but it hasn’t been confirmed yet. As of today, no exoplanets have been discovered around Alpha Centauri A or B. There are several ongoing projects to search for habitable exoplanets in Alpha Centauri: The Expresso spectrograph, which started operating in October 2018, is able to detect radial velocities of less than 10 cm/s. Another promising instrument is called NEAR, which stands for Near Earths in the AlphaCen…

Can there exist an unusual planet where according to some strange pattern of rotation no seasons of year and no significant difference in temperature between different places on the planet? It means there is days and nights but all places on the planet are illuminated by the star with the same intensity and periodicity. For example, what if planet exhibits very fast and large axe precession?

Does anyone think we could discover an asteroid that has a very large quantity of precious metals? Maybe we could find an asteroid that has more gold than the earth has? If we found an asteroid that is so valuable, maybe it could be towed into Earth orbit and the metals could be extracted in nearly zero g and then send to Earth by parachute. What about "rare earth" metals?

I am looking for information in the form of a table where there would be the following columns: galaxy-distance to it - the rate of removal-the mass of the galaxy-the mass of the Central black hole

Does the term habitable zone in relation to the brightness of a star and the distance of a planet from a star give rise to misconceptions about exoplanets? Our own solar system is an example, Venus, Earth and Mars are in the habitable zone. A super earth could be habitable well out into the what we call the asteroid belt but would not be if it was close as the Earth. Sara Seager has suggested that a super earth might be habitable well past the orbit of Jupiter if it had a thick hydrogen atmosphere. Then you get into the whole ice planets or moons with frozen over oceans and if we find life on Titan as Chris McKay and Heather Smith have suggested then the entire con…

Okay, I just saw this short 3 minute video about our universe coming from nothing. In it, the narrator says that gravity is the counterpart (negative energy) that balances the universe to a total value of 0 energy. Is that correct?

I say it has to be infinite because if it is finite - how does it stop? what lies on the other side? Voids is not an answer- even a void takes space.

Its my contention that the Universe has always been here.

Is it possible that an extremely large comet or other such object could hit earth suddenly with little warning ? or is this something we would expect scientists to know about years /decades /centuries in advance? how much advance warning would we expect to have ? And how big and fast would it have to be to be catastrophic for human life ?

Should you one day find yourself with too much time in spare, and wanting to try out something difficult and extraordinary, why not build a wormhole? https://www.sciencealert.com/physicists-have-published-instructions-for-diy-wormhole Warning: Gaining the tools and parts for this garage project, might be impossible, so arm yourself with lots of patience and optimism!

if you had the ability to tour the galaxy without having to worry about the time it takes to get around lets just say you were immortal and time didn't matter, or you could travel fast enough what spectacles would be worth seeing that you cant see from earth?

I read someone's unified field theory answer on Quora. Looks like he said one could be made, if dark matter and gravity is the same thing. So gravity as a free agent, attracted to large quantity of normal matter? Would explains the difficulty finding gravity in particles. Could dark matter and gravity be the same thing? Any debunk would be appreciated!

The universe is allways expanding so based on that we can think that at some point in the past when it hasnt expanded to this point. that it was a one dense point in the space(The big bang theory). And it suggests that it was so dense and high in tempeture that there was nothing in it but particales pressed in to one point. So the theory now is that before the big bang there was nothing. But what if we look at it in a diffrent view?. Not so long ago using the headron colidor there were discoverd new particals, so small that how advenced we are now we cant look inside of them and see what they are made of. So they were called the ellementary particals. But what if we could…

Hello I have been asking myself this question since I saw the formula (II-30) on page 11 of this (unpublished) document: Indeed, [latex]d \Omega[/latex] is presented as a four-dimensional volume variation in general relativity for EINSTEIN equations in vacuum. [latex]d\Omega=\sqrt{|g|}dx^0dx^1dx^2dx^3[/latex] where [latex]x^0=ct[/latex] Assuming that this four-dimensional volume is composed of the three spatial dimensions and a temporal dimension, the following calculations can be attempted from the 2018 Planck mission results data. By making this assumption [latex]g_0[/latex] is no longer adimensioned but takes the dimension [latex]m^{-2}[/latex]…

The Wikipedia article for Cosmic ray { http://en.wikipedia.org/wiki/Cosmic_ray} says that they are mostly positively charged and that electrons (beta particles) constitute about 1% of galactic cosmic rays. The ones that impact on the earth's rocky surface must remain trapped inside it forever. However, the Earth appears to have no net charge, so what is the source of the electrons that offset this embedded Cosmic ray charge and how do they arrive? Also, is it likely to be so that whatever the sources are of Cosmic rays, that they must, after 13 billion years, now have an enormous -ve charge; or that the positive partners to Earth's neutralizing electrons drift…

https://phys.org/news/2019-08-evidence-cloaked-black-hole-early.htmlEvidence found for cloaked black hole in early universe: A group of astronomers, including Penn State scientists, has announced the likely discovery of a highly obscured black hole existing only 850 million years after the Big Bang, using NASA's Chandra X-ray Observatory. This is the first evidence for a cloaked black hole at such an early time. Supermassive black holes typically grow by pulling in material from a disk of surrounding matter. For the most rapid growth, this process generates prodigious amounts of radiation in a very small region around the black hole, and produces an extremely bright, c…

Hi all! We are looking for more observatories and amateur astronomers who might want to join the project. The Habitable Exoplanet Hunting Project is a worldwide network of amateur astronomers searching for new potentially habitable exoplanets. I am coordinating over 20 observatories located in 5 continents. We are searching for habitable exoplanets around non-flare G, K and M-type stars located within 100 ly. The stars we are monitoring already have known transiting exoplanets, but none of them are potentially habitable. We are monitoring each star 24/7 for several months. By doing so, we believe that the chances of finding an exoplanet increase f…