Astronomy and Cosmology

What are some scientific solutions to the Fermi paradox?

I need help understanding the diagrams I see showing worldlines of distant objects on a cosmological scale. From this paper http://people.virginia.edu/~dmw8f/astr5630/Topic16/t16_light_cones.html there appears this diagram, which appears in similar format on other sites. It is called the concordance model here. Note that this is comoving coordinates, plotting proper distance, not a spacetime diagram of an inertial reference frame, which would not be able to foliate all of spacetime like this does. It would seem that if space expansion was constant (no acceleration, no dark energy), then those worldlines (blue on left, dotted black on right) would be strai…

Can someone please explain to me what dark matter is, but not in a very detailed and complicated way, as I am still a beginner in this topic.

I am not educated on theoretical physics. I have very limited knowledge in the field and, from that knowledge, an idea came to me. I am more so looking to learn why the idea doesn't work than to prove that it does. Imagine a black hole in expanding space. The black hole emits Hawking radiation in all directions from its event horizon in the form of thermal radiation, calculated with the surface area of the black hole to find it's blackbody radiation in degrees Kelvin. This equation can be simplified to J=(3.3367086×10^-42)÷R, R being the Schwarzchild radius of the black hole in meters, J being the thermal energy emitted by the black hole in joules. Finding energy emi…

Really cool how they have finally captured an image of a black hole https://www.google.ca/amp/s/dailygalaxy.com/2020/03/the-black-hole-larger-than-our-solar-system-unveils-history-of-the-entire-universe-weekend-feature/amp/

Hi there! "Black hole creation" is obviously an absolute event at a given point in space-time, and black holes are created when a particular energy density threshold is reached. My problem is that kinetic energy is a relative calculation. If a mass is sufficiently dense to be close to the Schwarzschild radius, and we accelerate it, we can obviously surpass the required density threshold according to our frame. How does general relativity reconcile this?

And by making I mean grinding and polishing lenses, and if you are grinding and polishing lenses that someone else made why not skip this and start with molten glass. Me I would just buy a rig completed as I do not have time to make a telescope. So is there an advantage to being independent versus interdependent. Remember that you could also be independent and make your own silicon chips as well but that this is not possible, so is there an advantage to making a telescope?

This seems like a new find that the universe is not expanding at the same speed depending on direction. https://www.nasa.gov/mission_pages/chandra/news/universe-s-expansion-may-not-be-the-same-in-all-directions.html how does this affect what we currently know with the age of the universe, the end of the universe and anything else we know or we thought we knew. i have included the actual paper if anyone is interested https://arxiv.org/pdf/2004.03305.pdf

Gotta love Brian Cox, his series from 2017 is still making red on express.co.uk. Is he for real or just a celebrity who created a video? His title claims universe can end at any minute but when you read the article by any minute he really means in a very very long time. But, Professor Cox confirmed it would be a long way in the future before something like this happened. He added: “The time-scale for vacuum decay is many times the age of our universe, so it’s not going to happen tomorrow, but it’s still disconcerting to think that our universe isn’t the stable, eternal home we once believed it to be. https://www.google.ca/amp/s/www.express.co.uk/news/s…

Trying to understand this article. Are they stating if 2 supermassive black holes merge and are they claiming that they see 2 supermassive blackholes merging https://www.google.ca/amp/s/www.forbes.com/sites/startswithabang/2020/03/03/the-most-energetic-event-in-the-universe-hasnt-been-discovered-yet/amp/ thank you

hello everyone! i hope lock down isn't boring you ( even though we have great scientific intellect ) anyway i need help making a formula for my theory on GRB's ( gamma ray bursts ) can anyone help me i will give you the proof of the theory i have come up with and the explanation i just need a formula to be wrote down and you can share the credit with me on the paper!

so I am a little confused. I thought Fomalhaut was a small galaxy with numerous stars example Fomalhaut A , Fomalhaut B etc. Now the article states that Fomalhaut B disappeared but does not give information about Fomalhaut A and the other stars and exoplanets in Fomalhaut. So are those still there or did all of Fomalhaut disappear? And yes I know they think what they saw was a dust cloud https://www.nasa.gov/feature/goddard/2020/exoplanet-apparently-disappears-in-latest-hubble-observations

So if the planet nine that was found really does turn out to be a pbh the size of a grapefruit like some scientists think. At its short distance from earth what effects would we see as it gets closer to earth? I assume like other black holes it would slowly get bigger as it consumes objects in its path? cause if I understand right planet nine affects earth

Came across this interesting article about disappearing stars, there one minute gone the next. Curious to know is this in the same region of our galaxy or all over didn’t notice in the article that stated this? https://m.ednews.net/en/news/sience/408284-researchers-have-identified-100-mysteriously-disappeared-stars-in-night-sky#.Xf35w8pHSXA.facebook oh and happy Easter to all

I found this article kind of cool it talks about how the cold spot can actually be made from a dent with another universe. They do think the idea is far fetched though. https://www.scientificamerican.com/article/could-cold-spot-in-the-sky-be-a-bruise-from-a-collision-with-a-parallel-universe/ anyone have thoughts on this, also I always thought they there were more than 1 cold spot in our observable universe would that mean multiple collisions?

Came across this paper while I was looking up entropy. Now I am not sure if I am reading it right but the conclusion section seems to imply false vacuum started due to large neutrinos. I am not sure if I am reading that right. I can copy and paste the section if anyone would like but was told not to do that last time. Here is the paper https://arxiv.org/pdf/1811.01991.pdf

So 2 weeks before his death Hawking released a paper about the end of the universe. I believe it was called exit to eternal inflation. It states that one day I am not sure timeframe the universe will end because everything burns out. I thought that that scenario already existed call Heat Death or something like that. So did he really predict this? or did I misunderstand his last paper?

We know that the further we look into space, the further back in time we are looking. So for example, when we look thousands of light years into the distance from planet Earth, we see things like incredible giant gas clouds (nebula), stars, galaxies. But we know that some of those stars we are looking at may not actually even be there anymore, as they may have since collapsed and died, maybe even become black holes which we cannot see and wouldn't be able to see for billions of years. Some of the galaxies may look completely different right now to how they appear and some of the nebula may have long disappeared. We cannot know because we can't see these things as they are…

So if I am reading this right they discovers that the universe can be either 9 billion or 19 billion years old so this changes it from the current thoughts of 14.9 billion “ When the Hubble Space Telescope was launched, the uncertainly over the universe’s expansion rate was off by a factor of two. This meant that the universe could be as young as 9.7 billion years or as old as 19.5 billion years. The younger value presented a huge problem; it would mean the universe was younger than the oldest known stars https://hubblesite.org/hubble-30th-anniversary/hubbles-exciting-universe/measuring-the-universes-expansion-rate

My questions about Hawking Radiation: (1) When 2 virtual particles appear near the event horizon, how far apart are they? It is hard to imagine how one of the pair enters the black hole, but the other one doesn't. (2) How long would virtual particles exist before they merge and annihilate if they are nowhere near any black hole? (3) How many of these virtual pairs can pop in and out of existence in a cubic meter of empty space during one second? "...Close to the event horizon of a black hole, a local observer must accelerate to keep from falling in. An accelerating observer sees a thermal bath of particles that pop out of the local acceleration horizon, turn arou…

In another thread I saw a comment about Hawking radiation, which I found confusing, and it's repeated in other online sources: that Hawking radiation is electromagnetic. I'm not a cosmologist, so I'm missing something here. The common explanation for Hawking radiation (e.g. https://www.universetoday.com/40856/hawking-radiation/) is "this process is also called black hole evaporation. In brief, this theoretical process works like this: particle-antiparticle pairs are constantly being produced and rapidly disappear (through annihilation); these pairs are virtual pairs, and their existence (if something virtual can be said to exist!) is a certain consequence of the…

Hi all some questions for the asteroid on April 30. According to NASA it will be 16 times further than the earth to the moon. 1- How can they know this for sure? 2- How do we know they are being honest with the distances? 3- are they the Only ones able to make these calculations? 4- Several news sites had articles that it would hit and this was secret info from NASA? 5- another site claimed that the Coronavirus was brought up to keep people isolated because of this asteroid to avoid mass panic, so how do we know what’s real vs fiction on this? These things make it hard to determine what is right dosent it? thank you

Do they pull or push earth in/toward the sun?

I heard about this from Neil DeGrasse Tyson on the Stephen Colbert show last night. Does anyone know what caused this? The "bang" or gamma ray burst was so giant that it carved a hole 1.5 million light years wide through a galaxy cluster. The article says nothing about the mass of the supermassive black hole. It must be tens of billions of solar masses, maybe the result of the merger of 2 ultra massive black holes during a galaxy collision? Any ideas? Is was a quasar for hundreds of millions of years, to produce that cavity. Why do they call that a "bang"? It was a giant quasar. “But it happened very slowly – like an explosion in slow motion that took pla…

I just saw a documentary on Netflix called "Bob Lazar, Area 51, and Flying Saucers." Bob is an interesting character who seems very credible. The narration by Mickey Rourke is a bit surreal, but the graphics are interesting. I watched the movie a second time, with captioning on so I could read it all, because I wanted to investigate this movie more carefully. Has anyone seen this Netflix, or are you familiar with Bob Lazar? He claims there are up to 9 alien saucers at S4, and a couple of them operate. Bob was reverse engineering the gravity propulsion, that uses an antimatter reactor that works by a stable form of element 115. He was raided twice by the govt. …