Astronomy and Cosmology

Does anyone know about how long it will take for the human race to build unmanned interstellar probes to be sent at the highest speeds possible to nearby stars? These would be sent to stars we find with nice Earth-like planets. Easier to build a craft for a one-way trip and there are no humans to support. There is no mention in this wiki article about interstellar probes using multiple methods of propulsion. Such a craft could be built in Earth orbit. It should be as small as possible so less mass needs to be accelerated. How about start it off using conventional rockets to get away from Earth. Ion thrusters can help. Then kick in the nuclear pulse propu…

Astronomers Have Discovered a Super-Fast Star System That Seems to Break Current Physics Models http://futurism.com/astronomers-discovered-super-fast-star-system-seems-break-current-physics-models/ Anyone here got any ideas what could be doing this? Or is there some thing wrong with the understanding of physics

I was lied to again by the mods and asked to not speak about time? Ha. I prefer truth and honest to evil repression. Kids...run for you lives from here!!!

How are these concepts related? Correct me if I'm wrong but I seem to remember something like for spacetime to exist, there must first be matter/energy. At the big bang, energy (not matter quite yet) expanded from a point (why not a giant rip?) outward rapidly. That was the beginning of time as we know it. We call it spacetime. That energy cooled and finally congealed into hydrogen and helium. There was no dust until the first generation of stars exploded millions of years after the big bang, just gas. So for spacetime to exist there must first be matterenergy. The next thing I wonder is before the big bang there may have been something like empty space,…

What is time according to science or in reality? I don't think they really know, do they? Let's see.

What is the most popular hypothesis for what dark energy is

Does time as we know it exist, or exist exactly the same as on and near earth? This may be unknown, so here is your chance to prove...or rather support with solid evidences that is does! If time does not exist, that means we do not know the distances to any far star. After all we need time for light to travel..light years etc etc. That would mean cosmology is basically a religion, or belief system only.

Clearly the vacuum energy has not been measured everywhere. Can I assume the vacuum energy is more or less constant everywhere, or is it possible some places have a different vacuum energy than other places?

Hi everyone. This is my first post and I am a novice, but have an interest in planets and orbital patterns. Is it possible for a planet to orbit a sun and be in partial or complete darkness for long periods of time - for example a year or more? If it is possible, would it only be because of of the planet spinning on its axis, or could it be because the elliptical orbit is uneven and takes it farther away during one phase then closer during another? Would the planet be able to recover from the lack of photosynthesis and freezing conditions of being in darkness for a year? How would this affect life on the planet? I welcome any comments or explanations in relation to this…

Let say an object (orbiting the sun) not only would be affected by gravity, but also by a (weak) force accelerating the object between aphelion to perihelion. This would increase the orbit radius, but it will so far I understand also affected the perihelion precession How can the perihelion precession impact be calculated?

How strong is the perihelion precession anomali of the earth

Hi, my first question is, what is the official line on what happened before the big bang? I have been told three things: - Two branes collided creating a big bang. - There was no space or time before the big bang, space and time came into being with the big bang. - We don't know. My second question is similar but instead is about the fate of the universe. Is this article on wikipedia an accurate one? https://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe Thanks.

Five supernova in a thousand years means the average time between them is 200 years. The current average for the observable Universe is three per 100 years = 33.3 years. Some may have occurred in the Milky Way that were not observed, but none were observed in the past hundred years. Even if we assume there were an average number in the 18th and 19th centuries, we are still deficit three or four. Is there some reason other than statistical variance that the Milky Way would be producing fewer than an average number of supernova? It seems possible this deficit may have allowed intelligent life to evolve. Is it known whether a some galaxies produce fewer supernova, for exampl…

've been working on a new postulation. Nothing new, to some, many of you may have done the same. If/when you postulate a beginning of the universe, it helps if you can understand other work. I have issues with Lambda-CDM because I believe its something of a contradiction in terms. Its believed to be science, but the line between supposition and evidence, when one refers to Lambda-CDM principles is not simply not clear. If you could draw a line through this collection of science, err... evidence and supposition is it possible to do it in a clearly defined fashion? I've picked a spot. I'd like to hear comments before revealing my choice, should you be so inclined.

Here are 2 of my pet peeves about astronomy documentaries, or in this case the series "How the Universe Works" on the Science channel. I love programs about astronomy and cosmology, that is the biggest picture of all. Today is Tuesday and Science channel is showing "How the Universe Works" all day. I will probably watch several for the 2nd or 3rd time. Don't get me wrong, I love the series "How the Universe Works" but occasionally I hear something that hurts my ears. Michio Kaku made the statement that our galaxy and Andromeda galaxy are racing towards each other at "a quarter of a million miles per hour". I have no reason to doubt the speed, but the way he …

I understand the two experiments sought different answers, but are the question really different?

What do you think the odds are of a Planet being habitable, and how did you reach that conclusion?

Hi, I am new here! So excited to be apart of this. I currently am in college studying biochem! Although, I love science as a whole! except math isn't my favorite or my strongest, but I can deal with it! Anyways, I came onto the astronomy and cosmology to ask what books are best to read about the universe! This can be everything from actually physics to the stars. I am looking for a book that kind of has it all, or at least some you all can recommend. I am really more so looking for a book where I can LEARN, and educate myself. I'm not looking for a textbook, like they use in school. Nor am I looking for a "novel". I want a book to read that has info/theories wher…

My hypothetical situation is: 5000 satellites in orbit around a star, lets say Barnard's Star. Each satellite is 400x400 kilometers and they are evenly distributed in orbit, which is 25 million kilometers from the star. They would only cover about 5% of the star and there would be equal coverage throughout their orbits, as some satellites go behind the star, new satellites would be coming out. The amount of light wouldn't change all that much, maybe a slight dimming and brightening on the left and right edges of the star. I read they have a candidate star that could be a Dyson Swarm but they are thinking it might be comet fragments. Anyways, I was wondering if my …

Hi there, Energy from matter is there to be observed when radioactive material decays but I think I'm right in stating, that it wasn't until 1997 that anyone managed to achieve the reverse process, in a cyclotron. There's lots of exciting observational data appearing about black holes right now. Reading the theory about bh's, it seems you have all of the necessary conditions for the creation of matter from energy. While there's much talk about the production of energy from the shredding of stars and such, nobody is talking about the creation of matter from energy. Can someone kindly tell me what I'm missing about black holes? Cheers☺

In this tread I would like to focus of the following paradox of the current mainstream. 1. The cosmologic constant must be constant 2. The Total Energy of the Universe must be constant Normally, Paradox is clear indication for an error. Let me use the following example: In Sudoku, sometimes we are obliged to select a random number out of the available options. Just later on we can verify if our assumption was correct or incorrect. So, if we get two same numbers at two spots on the same row, we know that this paradox is an indication that we have made a mistake in our selection/assumption. Normally, it is expected that based on this p…

how do scientist accurately record data when the data they are recording from satellites and telescopes are showing us history and not the exact events happening now?

Dear Mordred Now we know that new mass/energy is created constantly in the Universe. However, do you agree that this was the basic idea of Fred Hoyle , as It is stated: https://en.wikipedia.org/wiki/Steady_State_theory "..This requires that matter be continually created in order to keep the universe's density from decreasing."

How would Modern Science disprove the possibility of autonomous ET's colony hidden under surface inside some celestial body of the Solar System? Can such hypothetical undersurface base sustain a colony with population of say, 5 thousand beings (as a model one can use humans because of known biology) for, say 2000 years and remain undetected until now? I've Googled some info about technosignatures, biosignatures and waste heat production but I' don't have enough data and enough knowledge in biology, physics and industrial processes as to reject such hypothesis or accept it. Thanks in advance to everybody for your attention and time!

If the Hubble Law is ultimately based on this fact: Galaxies that are farther away have a faster regression speed. And from that we conclude: The expansion of the universe accelerates as it grows. Then what about the statement: Galaxies that exist later in time have a slower regression speed. Symmetry should tell us that: The expansion of the universe decelerates as it ages. Both statements should be true but how does the expansion of the Universe do both? accelerate with distance decelerate with time Does anyone else see a second order Lorentz transform here? Just puttin it out there. Edit to clarify: Since we found expansion accel…