Astronomy and Cosmology

Hi again. I hope everybody is well. Without further ado, is there any appreciable difference between matter that has gravitationally collapsed from a primeval cluster made up of mostly hydrogen and matter that has collapsed several times within a certain galactic region? I suppose matter that collapses again and again in regions where many supernova explosions have taken place before would be richer in heavy elements. Could the wild variation in the types of stars as reflected in the Hertzsprung-Russell diagram reflect this variation in the "degree of collapse" that there is in the universe? My intuition tells me that, if all stars had started up from a uni…

The new cosmocalculator is out they had to change the host site. There is still some bugs being resolved however they increased the flexibility of the calculator http://jorrie.epizy.com/LightCone7-2017-02-08/LightCone_Ho7.html?i=1 [latex]{\scriptsize\begin{array}{|r|r|r|r|r|r|r|r|r|r|r|r|r|r|r|r|} \hline z&T (Gy)&R (Gly)&D_{now} (Gly)&Temp(K) \\ \hline 1.09e+3&3.72e-4&6.27e-4&4.53e+1&2.97e+3\\ \hline 3.39e+2&2.49e-3&3.95e-3&4.42e+1&9.27e+2\\ \hline 1.05e+2&1.53e-2&2.34e-2&4.20e+1&2.89e+2\\ \hline 3.20e+1&9.01e-2&1.36e-1&3.81e+1&9.00e+1\\ \hline 9.29e+0&5.22e-1&7.84e-1&3.0…

Does anyone know how small a nuclear explosion can be? The smallest I could find is the Davy Crocket. "The smallest, known deployed nuclear bomb was the W54, which had a blast yield equivalent of between 10 and 20 tonnes of TNT (in the neighborhood of 1/1000 the power of the bombs used on Hiroshima and Nagasaki)." Is it possible to scale this down even more so you have tiny nukes that don't weigh very much but they can put a huge impulse on a pusher plate of a small, unmanned, interstellar probe? "Daedalus would be constructed in Earth orbit and have an initial mass of 54,000 tonnes including 50,000 tonnes of fuel and 500 tonnes of scientific payload. Daed…

Hi, I have read here under (2.1) that [math]c^5/(G \hbar \Lambda_{s^{-2}}[/math] is a "fundamental pure number" It's the word "fundamental" that questions my mind. What is that fondamental notion please?

Dear scienceforums.net, This would be my second posting and thought this would be the proper section to put this in. I've been trying to construct a generalized python simulation for any arbitrary n-bodies with predefined randomly assigned momentum and velocity. So far it was going well and even the initial run through went smoothly without many errors to be fixed but when graphing the data it seemed to me to be incomplete. Either I was shifting through the data wrongly, the initial conditions were off enough to not allow for a smooth nearly closed n-body system, or i've been wrong about the whole program apparatus to begin with. I should note that I use something c…

Hi This is probably a really simple question, but I have written a small python application that adds two numbers together, and I want to expand this so there are more entry boxes so I can make a program that can solve a drake equation for a given set of figures. This is more of a proof of concept and personal challenge, Looking at the equation on WikiPedia https://en.wikipedia.org/wiki/Drake_equation Am I right in thinking that I have to multiply all the values together ? as this just shows dots between the various variables. I think I remember reading somewhere that dots in equations mean multiply but that was years ago. Writing a…

Physicists Announce Potential Dark Matter Breakthrough https://www.scientificamerican.com/article/physicists-announce-potential-dark-matter-breakthrough/ Just spotted a link to this., so my question is Does this mean that Axions will appear on the Standard Model of particle physics. ? Paul

(Sorry if this seems obvious/stupid) Correct me if I'm wrong. AFAIK when temperature is decreased, the molecules become closely packed, thus increasing the density. Then how do we say that the universe was extremely hot at the beginning when it was all packed into a few cubic centimeters?

Looking at space and time, relativity, and matter, I have prompted a question in my head. If time is reactive to something, it implies that it travels. Photons have mass when they are traveling and they travel at the speed of light. It takes around 8 seconds for light to travel from the sun to Earth. The same concept can be procured from terminal velocity of a falling object. It reaches a set speed based on its mass to resistance of the matter it is traveling through. So, the thought in my head is that space itself has resistance. Since light is composed of photons, and they have mass, then the time it takes them to travel a distance implies that there is a c…

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