https://www.reddit.com/r/askscience/comments/w3n2ex/ask_anything_wednesday_physics_astronomy_earth/
created by AutoModerator on 20/07/2022 at 14:00 UTC
931 upvotes, 159 top-level comments (showing 25)
Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on **Physics, Astronomy, Earth and Planetary Science**
Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical /r/AskScience post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...".
Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit /r/AskScienceDiscussion , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists.
Please only answer a posted question if you are an expert in the field. The full guidelines for posting responses in AskScience can be found here[1]. In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for /r/AskScience.
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Past AskAnythingWednesday posts can be found here[3]. Ask away!
Comment by jmsbrk at 20/07/2022 at 14:57 UTC
85 upvotes, 1 direct replies
The Large Hadron Collider - ‘a collider of large hadrons’, or ‘a hadron collider that is large’?
Comment by Panouza at 20/07/2022 at 18:42 UTC
85 upvotes, 2 direct replies
I’m guessing this is a physics or fluid dynamics question - When shaking a closed container with a fluid inside (say water) to clean the inside of said container, is there an optimal amount of fluid to clean it?
I ask as I notice when shaking a closed container at 100% full with water it doesn’t feel like it’s moving/swashing inside, but when it’s 1% full it doesn’t seem to have enough mass/movement/kinetic energy inside to clean it.
Apologies for the really crude and maybe confusing question.
I can imagine there are a lot of variables to this, like the viscosity of the fluid, the particle material and size of what you’re cleaning off (E.g cohesive and non-cohesive particles). The container dimensions. The frequency and amplitude of the “shaking”. Or! I could be over thinking this.
Comment by TeeDeeArt at 20/07/2022 at 15:45 UTC*
32 upvotes, 3 direct replies
I always hear about how black holes have no hair*, just 3 properties, mass, spin and charge. (While also being aware of other theories, like fuzzballs)
3 things about that stand out to me. When two black holes of 13 solar masses merge merge you get a dumbbell shape mass distribution before ringing down. It's not just a black hole of 20 sun's mass (assuming 6 or so lost to gravitational waves). It's different to how it will be in the future, when it will be a nice simple round spinning black hole, at the moment it is a weird construct with two seperate singularities and an entirely different shape? So is shape or mass distrobution a 4th quality? Next, as a black hole evaporates, it should send out higher and higher energy particles as hawking radiation, not just weak ass photons right? Eventually it will also be throwing out Z and W bosons and gluons? So would it not also have other properties relating to the strong and weak force?
And what's the deal with the higgs field not being 'a force'. Its a field that is giving a load of particles their mass right? So is it a field, one that's working inside of black holes? Does the matter in there then not necessarily also have that property, and then so too do black holes?
I keep hearing about how the curvature of the universe is flat (within a certain testable bound). Would increased amounts of matter and gravitational force have meant it was not flat? If so, did the previously higher amounts of radiation (photons and gravitational waves) which in early epochs exerted a greater gravitational influence before being redshifted and losing energy, would these have meant the universe was not in fact flat in earlier times? Did the universe then *become* flat or is the curvature of the universe independent of the matter and energy content of the universe?
What are the options for 'seeing' past the cmb? Neutrinos, gravitational waves, and shapes and patterns in the cmb, looking at how it is flowing towards, and redshifted by, matter beyond it which we cannot see. Any other options, and how much info are we getting from them? Last I heard it was a couple of neutrinos per week or something, nothing to really paint a picture? Are there any options I've missed, ones I am unaware of? And also, just how opaque was it? Is absolutely nothing able to be seen past the gas before recombination? Is there no frequency that was able to make it through a bit better?
Comment by tebla at 20/07/2022 at 14:32 UTC*
16 upvotes, 6 direct replies
is it likely there will be a point where physics is 'finished'? where we perfectly understand all the mechanisms of the universe, its history and future. On a scale of 0% understanding of physics (pre cavemen or something) to 100% perfect and complete understanding, how far along do you think we are?
edit: by saying know it's future I don't mean know everything that will happen in the universe in the future, more know what is likely to happen to the universe at a large scale
Comment by [deleted] at 20/07/2022 at 14:26 UTC
11 upvotes, 1 direct replies
I have two questions regarding exoplanets.
1. Is it possible for a planet to orbit a black hole in a proximity that wouldn't exclude a possibility for us to explore it, once we manage interstellar travel?
2. Basically the same question regarding hypothethical pulsar systems.
Sorry if these sound dumb. I'm a newbie.
Comment by NigelDweeb at 20/07/2022 at 14:52 UTC
20 upvotes, 4 direct replies
If I am in a spaceship and the ship is accelerating at 1g then that ship needs to expend a large amount of energy to maintain that acceleration.
Stood on the surface of the earth I am still subject to the same acceleration - where does the energy come from to maintain that 1g.
Both are accelerations - one as a result of converting fuel - the other as a consequence of the warping of spacetime by the mass of the earth.
But it seems you get 'something for nothing' once the initial warping of spacetime is achieved - the acceleration is constant.
What am I missing?
Comment by aluminium_is_cool at 20/07/2022 at 14:16 UTC
8 upvotes, 2 direct replies
is there either an upper or lower limit to the frequency of an electromagnetic wave?
Comment by TheTurtleVirus at 20/07/2022 at 16:25 UTC
9 upvotes, 3 direct replies
I've searched for the answer to this question before but have never been quite satisfied with the answer. What would length contraction of a disk spinning at relativistic speeds look like for an outside observer? Obviously you have to ignore the fact that the disk would be ripped to pieces before it ever reached those speeds.
Comment by caf4676 at 20/07/2022 at 16:01 UTC
8 upvotes, 5 direct replies
If there are billions of stars in the galaxy, why is the sky dark?
Comment by HungTDD at 20/07/2022 at 16:57 UTC
8 upvotes, 2 direct replies
Are the images of the black hole from the Event Horizon Telescope free use? Are we allowed to add them into books without infringing on copyright laws? I'm writing a book on astrophysics and would very much wish to use them.
Comment by CaptainMarsupial at 20/07/2022 at 15:25 UTC
7 upvotes, 1 direct replies
About The chip- sized probe they are talking about sending to Alpha Centauri by lasers. How fast could it go, and would it be able to do science if it’s traveling really fast?
Comment by [deleted] at 20/07/2022 at 17:05 UTC
6 upvotes, 1 direct replies
[deleted]
Comment by kori08 at 20/07/2022 at 15:51 UTC
12 upvotes, 2 direct replies
Hey there, first time here. There was a topic that sparked my interest yesterday.
Growing up in the 90s, you can't avoid reading about Dolly the cloned lamb. It was such a controversial topic that started so much debate!!
That makes me wonder, why haven't we heard anything new about cloning technology since then? It's kinda like people lost interest in it after Dolly died and no one attempted something of that spectre ever since.
Do any smart minds here have any insights on that? Thank you!
Comment by Gerryislandgirl at 20/07/2022 at 15:44 UTC
6 upvotes, 1 direct replies
How do high cliffs by the ocean form? Why don’t they become beaches?
Comment by Excellent_Let_8011 at 20/07/2022 at 16:45 UTC
4 upvotes, 1 direct replies
What would happen if a nuke - not Tsar Bomba but a more common device - exploded inside its bomber? I know detonation elevation affects destructive power but that is close to the ground. Would an explosion at 50,000 feet cause massive damage on the ground or would it be a blinding flash of light and maybe a heat blast and not much more?
Comment by Thortok2000 at 20/07/2022 at 17:11 UTC
6 upvotes, 2 direct replies
I saw in a video game yesterday that the moon is slowing the earth's rotation. Is this for real or was it a part of the fiction of the game? (The game is called 'Stray'.)
If it's real, then what is the end result, how soon will it happen, and what are the consequences of that end result (and along the way)?
Comment by Shotist at 20/07/2022 at 17:20 UTC
5 upvotes, 4 direct replies
This is a fairly basic question but:
How do I contribute to Astronomy science as a very low budget backyard astronomer? I love space a ton, and missed my calling getting into astronomy professionally but would still really enjoy having some form of contribution to the scientific community.
Comment by Haha71687 at 20/07/2022 at 16:43 UTC
3 upvotes, 2 direct replies
Dark matter halos.
If dark matter doesn't interact in any way other than gravitationally, why would it "clump" around galaxies? Wouldn't you just expect the dark matter particles to zoom out of a sphere of influence just as fast as they zoomed in?
I'm probably missing something here because I also can't really think of how a planet would capture a moon without it leaving just as fast as it arrived. Where does the energy go that is lost in circularizing the orbit?
Comment by dark_enough_to_dance at 20/07/2022 at 16:46 UTC
3 upvotes, 2 direct replies
I have a question about Webb images. How do we exactly know where a galaxy is located exactly? I couldn't find a reliable source on this topic, thanks.
Comment by newbiDev at 20/07/2022 at 17:28 UTC
4 upvotes, 3 direct replies
If we created an unbreakable cable that was light enough to not change the moon's orbit could we attach it to the moon and a rail on earth that goes around the world to create energy?
Comment by PaulsRedditUsername at 20/07/2022 at 18:10 UTC
4 upvotes, 2 direct replies
A question for physicists, chemists, mathematicians, other people who work with very tiny or abstract things:
When you are doing work on inflaton fields, or quantum foam, or atoms exchanging electrons or whatever, do you have a picture in your mind of what it "looks" like, or is it enough to work with the numbers and data?
As a simple-minded outsider, when I think of hydrogen bonding with oxygen, I always have an image of two magnetic pool balls coming together and attaching to one another, even though I know this isn't how it really appears. When I hear a lecture telling me that subatomic particles are more like waves of energy, I picture a little glowing wave flying through space, undulating like a flatfish.
In short, I must always draw a picture. Do you professionals do this, too? If so, what images help you the most? Are some images more accurate than others, and does it matter?
Comment by ThatManSynthious at 20/07/2022 at 20:11 UTC
4 upvotes, 1 direct replies
Is landing on/exploring Venus at all possible/plausible?
I understand the environment is extremely harsh. The few vessels that have landed there have melted quickly after. If we ignore cost, would we be able to manufacture suits that can let astronauts survive on the surface? Would it be possible to make a ship out of materials that wouldn't melt on its surface and also be strong enough to get the astronauts back into orbit? How big would such a ship need to be? Are we technologically advanced enough to do this now? In 10 years? 50? 100?
Venus has always sort of been brushed off as an explorable planet and all we ever hear about is The Moon, Mars, and occasionally some of the Galilean moons such as Europa.
Comment by Akagiyama at 20/07/2022 at 15:30 UTC*
7 upvotes, 3 direct replies
Why are all subduction zones underwater?
EDIT: Thanks for the awesome information!
Comment by ty88 at 20/07/2022 at 17:30 UTC
3 upvotes, 1 direct replies
If fusion reactors like ITER are going to need tritium for fuel, why wouldn't it make sense to extract it from the processed Fukushima water that they're going to just dump in the ocean? Would it be too contaminated with other radionuclides (after reprocessing)?
Comment by velahavle at 20/07/2022 at 17:32 UTC
3 upvotes, 4 direct replies
"Put two ships in the open sea, without wind or tide, and, at last, they will come together." - Jules Verne. Is this correct and if so, why?