How Cold Are Moon Shadows, Why Are Dark Matter Halos Spherical, War For The Moon | Q&A 251

How cold does it get in the shadows on the Moon? What's going on with dark matter research? Can we chase Oumuamua with a solar sail spacecraft? Will we ever face a war for the Moon? Answering all these questions and more in this week's Q&A.
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00:00 Start
00:29 [Andoria] How cold do shadows on the Moon get?
05:34 [Vulcan] Why are dark matter halos spherical?
08:48 [Risa] Are we alone in the Universe?
12:26 [Aeturen] Will there be a war for the Moon?
15:40 [Vendikar] Current obsessions
19:58 [Remus] What's going on with dark matter?
23:52 [Janus] Can we catch Oumuamua with a solar sail?
29:07 [Cait] What are the Hawking radiation particles?
29:52 [Betazed] What caused the Big Bang?
29:57 [Cheleb] How to transfer energy from space down to Earth?
33:49 [Nimbus] Will dark energy eventually decline?
36:44 [Belos] Is the risk of solar flares overblown or unappreciated?
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[@trainyoumust]

As the French astronomer André Brahic used to say “if we’re alone in the universe we will never know” ❤

[@jamesw3746]

"But I try not to think with my gut. Really, it’s okay to reserve judgment until the evidence is in." ~Carl Sagan

[@Collectible_Andy]

Fraser’s explanation about how trivial fighting over the moon would be had me laughing in bed next to my sleeping wife. She woke up and i couldn’t even begin to explain why I found it so funny. Was one of those nerdy, you had to be there moments for me.

[@lerm4676]

Dont underestimate the greed of people or the power of fear. It can make nations do irrational things. The fact that it makes you laugh, imo is arrogant and dismissive of legitimate threats.

[@robotaholic]

Intellectual honesty is so refreshing. Hearing idk is wonderful especially compared to know it all religious dogma

[@richardloewen7177]

BOTH science and religion struggle with this delineation.

[@robotaholic]

@richardloewen7177 nope. The scientific method and publishing papers with peer review is a way to really get to the truth of an hypothesis by ppl trying to disprove it for money. In. Fact, the ability to be disproved must be in the theory or it isnt science. ....religion has no self correcting function and in fact it stubbornly believes it is immune from change as God and its qualities are unchangeable and so it will be discarded as it isn't useful in the pursuit of information or making predictions with models.

[@jensphiliphohmann1876]

​@@richardloewen7177 Not equally.

[@cameronwalker294]

Wrong again. Christian's who are scientists freely admit to things we dont know. It is those who insist that 'Climate change is a fact, fact, fact' that are lying to everyone including themselves.

[@talkingmudcrab718]

"We don't know" is a perfectly valid answer. Particularly from a scientific standpoint. Thank you for your honesty Fraser. I'm totally with you, but only because I've got the same basic opinion after years of careful and serious study. I am always wary of bringing emotions into scientific questions, but i do have emotional opinions on these questions. I just think they tend to be less valid. It is what it is.

[@hugegamer5988]

Saying “we don’t know” to what is dark matter is wrong, and lends credence to ignorance. Dark matter is an observed phenomenon, using the known laws of gravitation we see variability in how stars orbit in galaxies. If you simply had one set of physical laws then that is not possible unless there is something unseen. Further, light is also bent in a variable way for the same visible mass as if something is there so it’s also not just getting gravity wrong or imagination. Also the angular power spectrum of the cosmic microwave background is consistent with dark matter. Saying we don’t know is lying because we know many things about it already. It is a very real and observable phenomenon.

[@CyberiusT]

"I don't know" has always been my preferred answer for ambiguous matters like that. I actually get a bit annoyed with people who state their opinion or belief as fact - but just a bit, because so very many people do it: it's expected behaviour.

[@surferdude4487]

When I state my opinion, I preface the statement with "In my opinion" Often, people agree with me, but, it's so much more fun when it leads to a respectful debate.

[@bdr420i]

"I'm a scientist journalist" 🎉😂 dude you're the best 💕

[@symmetrie_bruch]

that´s not what he said, and that´s not what he is.

[@larrybuzbee7344]

Perfect answer to the IDK issue. I would add that science is all about questions, answers are incidental, only ever provisional and at best just steps onward to new questions. Religion discredits itself by claiming to possess all the unquestionable answers and that's why science faces so much opposition from that quarter.

[@NorasGuidetotheGalaxy]

Hey that's me!! Thanks so much for the shoutout 😊 Always happy to have more space and astronomy enthusiasts along for the ride!

[@frasercain]

Keep up the good work!

[@brainbark]

My vote is for Aeturen, on the basis of the "Lord of the Penguins" remark.

[@pelewads]

I would definitely vote for risa. I believe that social media has given us far too many "experts", today. Experts who in actuality don't know shirt. I have a tremendous amount of respect for someone who says "I don't know". So thank you.

[@sierravortec2494]

I’ve got no constructive comment just gonna say love the channel. Love the videos, keep them coming!

[@collemwillst1810]

My favorite space channel!

[@OtterSkull]

14:07 Idk... being lord of the penguins sounds really tempting to me 🐧😂

[@Drakcap]

I prefer emperor, but I couldn't find any stock footage clips fast enough to justify the joke, so instead they were gentoo penguins I believe.

[@Flowmystic]

We appreciate you and your team.

[@noelstarchild]

This post hits the spot Mr Cain. I have been wondering specifically about moon conditions. Thank you sir.

[@joepverlaan575]

Wow, good episode!! Well done👏

[@DominikJaniec]

thank you!

[@terminusest5902]

As we find answers we find new questions. JWST is a great example.

[@frasercain]

Yeah, it's a questions factory.

[@orlandoerickson2439]

As always so inspirational!

[@VideoconferencingUSA]

Nice job

[@LordPhobos6502]

Q&A vote: Risa. Andoria is a close 2nd place though.

[@kerbangol.8386]

Vulcan: Remus: Dark Matter---"I see you, you can't see me. But you react to me, even though I ignore you" 😎 so cool...

[@BigTimeRushFan2112]

philosophy, I see you masquerading as science....

[@surferdude4487]

I want to claim the title, "Lord of the Penguins". That sounds awesome!

[@LordPhobos6502]

This is something that seems to be lost on a lot of people; "I don't know" is a perfectly valid answer when someone doesn't know something! If you don't know something, don't try to make stuff up, be honest!

[@KarldorisLambley]

"i know less than i thought i did" thinking this is a good thing, as the dunning Kruger effect tells us.

[@JamesCairney]

The Dunning Kruger effect is when they don't know and think they do know everything. It's relative to competence, not knowledge. When calling out the Dunning Kruger effect, it's best not to be an example of it.

[@frasercain]

Zing.

[@KarldorisLambley]

@@JamesCairney It seems there might be a bit of confusion about the Dunning-Kruger effect. While it's commonly associated with competence, it's more accurately about the knowledge or understanding of one's own competence. The effect describes how individuals with lower competence tend to overestimate their abilities, while those with higher competence may underestimate theirs. This is because individuals with less competence may lack the knowledge or insight to accurately assess their own skills. So, when someone says, "I know less than I thought I did," it could indeed be an acknowledgment of the Dunning-Kruger effect if they had previously overestimated their competence. Recognizing one's limitations and gaps in knowledge is an essential step toward improving skills and expertise. The essence of the Dunning-Kruger effect lies in the discrepancy between actual competence and perceived competence, which is influenced by an individual's knowledge and understanding of their abilities. Therefore, it's accurate to say that the effect is about the knowledge of competence, rather than just competence itself.

[@KarldorisLambley]

@@JamesCairney It seems there might be a bit of confusion about the Dunning-Kruger effect. While it's commonly associated with competence, it's more accurately about the knowledge or understanding of one's own competence. The effect describes how individuals with lower competence tend to overestimate their abilities, while those with higher competence may underestimate theirs. This is because individuals with less competence may lack the knowledge or insight to accurately assess their own skills. So, when someone says, "I know less than I thought I did," it could indeed be an acknowledgment of the Dunning-Kruger effect if they had previously overestimated their competence. Recognizing one's limitations and gaps in knowledge is an essential step toward improving skills and expertise. The essence of the Dunning-Kruger effect lies in the discrepancy between actual competence and perceived competence, which is influenced by an individual's knowledge and understanding of their abilities. Therefore, it's accurate to say that the effect is about the knowledge of competence, rather than just competence itself.

[@KarldorisLambley]

@@JamesCairney you're wrong. it is about knowledge orf competence. when calling out the dunning kruger effect it is best to not be an example of it. lol

[@ryanquick1824]

VULCAN also, GREAT CALL on the 'i don't know' bit. THE THING that most people dont get about knowledge IS the FACT that the more one is aware of/KNOWS, the more they also realize how much there ABSOLUTELY IS that they do not know. it IS QUITE a PARADOX, indeed... INDEED.

[@-Thauma-]

Thank you ❤

[@JamesCairney]

Risa, good answer.

[@michaelgian2649]

Vendikar This is a question that I am adding to my repertoire.

[@roqua]

It was a very noticeable change to Fraser's interview lineup :)

[@nnevermore71]

Betazed!!! Loved it! Perfect answer. Loved that you addressed it.

[@savetheplantet5799]

We dont know is the realest answer. Why do we do this? Because we want to know. Pretty cut and dry. Do you fraser . Honesty and transparency is why we are all here . Thank you for all you do.

[@hugegamer5988]

The problem with solar sales is all the merchandise tends to just burn up before you can use it.

[@TheebayOffroader]

I'm with you on the vanilla.

[@weldonanderson5124]

The discussion re dark matter halo shape was especially interesting... it spurred me to some questions... if dark matter doesnt interact with itself or others through friction, does this mean it doesnt have conventional ways of losing say, angular momentum? This is a weird idea. No friction- then how would dark matter ever be converted to energy? Can it even be said to have volume (or density?) at all? What happens if it is packed into small volume if it is not interacting - i am thinking no friction also means no fluid dynamics, no gas laws? No temperature? No fusion, no stars. Crazily it almost makes sense that we can never "see" it, if it has no concept of temperature, it is not emitting any radiation whatsoever. So of course it's dark! Mind blowing. On the other hand, if it DOES interact with itself and others through gravity, i imagine it must be affected by gravitational waves, and relativistic effects, like time dilation and frame dragging. It is strange to think of a "dark black hole" since conventional black holes are so defined by what they do to light, and dark matter has no light to "trap" in the first place. Event horizon would have a pretty different meaning? Shadow universe indeed. [I am hesitant to post; seems too crazy].

[@LibertarianLeninistRants]

I have to disagree with the thesis of lack of incentive to claim the moon. The moon has incredible strategic potential. "The Moon is a harsh mistress" made this clear

[@sjpugsie]

That’s some crazy science

[@thentil]

I was with you on "we don't know" until you got to "what happens after we die"... Any answer other than "nothing" is magical thinking, about souls or whatnot.

[@frasercain]

There is no evidence that anything happens, but the honest answer is still "I don't know."

[@thentil]

@@frasercain There's very good evidence, from the millions of dead humans, mammals, life forms .... Electrical and mechanical activity ceases. Is there other activity we're aware of? Not scientifically. If the answer is still "we don't know" - if there's some special non-measurable component solely the property of... Homo sapiens? Homo rectus? Hominidae? Primates? Mammals? ... Then we may as well say there could be unknown and unobservable components to everything. It's a useless discussion at that point.

[@thentil]

Happy to have differing opinions though! ❤ (Seems like my reply was sent to /dev/null, perhaps because I used words yt thinks means something else. No problem!)

[@CheatOnlyDeath]

Saying "We don't know" to whether there is other life in the universe is tremendously different then saying we don't know what happens after death, despite that there is the same evidence (none) for each. And I mean scientifically speaking, without venturing into philosophy or religion. It's a very important point though I admit not having a supporting explanation concise enough for a comment. To be trite "all lack of evidence in not equivalent".

[@Raz.C]

I LOVE your answer to Grigor Khajehsari *(BETAZED)* @ 29:50 I can't help but feel that this was a bad-faith question. Maybe he was hoping you'd say "Obviously God is the only one would could have caused it." Maybe he was hoping that you'd just make up some science-y sounding answer, so that he could play "Gotcha!" The way you deftly avoided the traps, by simply answering with an honest, factual and brief "We have no idea!" was simply perfect! You Da Man, Fraser! You da man!

[@garyswift9347]

Andoria. - Thanks again Fraser, and team. For eternal sunlight on the moon, I'll bet you could build towers (easier to build on the moon). I vote for dark matter being gravitons accumulating, or unicorns.

[@BabyMakR]

27:08 better than an RTG. An RTG Stirling engine.

[@mhult5873]

[ Belos ] Thank you for another, as always, great video! Thank you. BR //M

[@jensphiliphohmann1876]

Not exclusively, but NIMBUS is quite interesting since it fuels another question about DE: As long as the fundamental relationships between physical quantities (nothing else are natural laws) don't change over time, energy must be preserved. So, if the total amount of DE is ever increasing, what other energy is converted into it?

[@benjaminbeard3736]

Vulcan. 100% because of your answer

[@mnichols1979]

14:10 I don't know, but Lord of the Penguins sounds pretty cool. Lol

[@Drakcap]

I would prefer emperor but I couldn't find stock footage of emperor penguins fast enough, so went with gentoo.

[@samgamgee7384]

Hey Fraser, just to you know: I now own the Moon! Next tome you talk about it, send me a check!

[@syringistic]

@Fraser Cain, at 28:08 - James Webb is at the Earth-Moon Lagrange point!

[@frasercain]

It's at the Earth-Sun L2 point. webb.nasa.gov/content/about/orbit.html

[@syringistic]

Well now I feel like a jerk! Thanks for correcting me, fantastic video :)

[@stephencoppins9467]

We are not alone in the universe. There are other mammals, reptiles, amphibians, birds, insects, fish and many other lifeforms that call this planet home, with their own languages, skill sets, and social communities and interactions. Just because we can’t understand them, doesn’t make them any less (or more) significant than humans.

[@ulicadluga]

10:13 NO. It is a fact the Strawberry ice cream sucks. The only thing you can do with strawberries is eat them with Yoghurt, Almond slices and lashings of Cretan Honey! 😊

[@JKKoneofakind]

Objectively false. Strawberry Ice Cream goes hard.

[@ulicadluga]

@@JKKoneofakind 😅

[@pencilpauli9442]

I don't know how cold moon shadows are, but I was carried away on one, and it was jolly well parky. Had to put on my cardi!

[@BoycottChinaa]

Cardi late to the party, Cat Stevens has been running from them for decades

[@archmage_of_the_aether]

flagged

[@pencilpauli9442]

@@archmage_of_the_aether Sorry, but I'm not getting the joke?

[@archmage_of_the_aether]

@@pencilpauli9442 it's less funny if i explain

[@pencilpauli9442]

@@archmage_of_the_aether It sounds like you reported my comment Which is even less amusing! lol

[@MichaelJohnJnr]

My Moon !

[@beastinshow2362]

Remus!

[@ashleyobrien4937]

Fraser- One could argue that there IS life out there in the universe, based quite simply on the fact that there is life HERE, we are part of the universe, but apart from that, just by inference, which we use a hell of a lot, the universe has a (so far) very strong habit of never revealing just one of anything, I know of no things in this entire existence where there is just one example of it, life on this rock is diverse, hardy, opportunistic, the universe is young, we are young, time is the only thing that is limiting our ability to give an absolute answer, I think it is safe to say, there's plenty of evidence that we WILL FIND life out there...

[@MsTyrie]

Dang...I didn't have "black hole choking on too much matter" on my bingo card. Perhaps Heimlich would have devised a maneuver for choking black holes. How can we find comfort in such a chaotic existence? "I'm astounded by people who want to 'know' the universe when it's hard enough to find your way around Chinatown". - Woody Allen (1935 - )

[@anthellis]

Not knowing the answer is what tomorrow is for.

[@rogertulk8607]

If the power companies install fusible links in places that would be most likely affected by a surge caused by a solar flare, those links would burn out and quickly shut down the system. That would allow a relatively quick repair of process as we would know where repairs were needed.

[@delveling]

name drop of sabine hossenfelder! "woot woot" !

[@CaliforniaBushman]

With Starship making it to orbit today, high efficiency perovskite solar panels in hexagonal sections that can self assemble in orbit. Sent up in bulk on just one Starship launch is a distinct possibility.

[@terminusest5902]

While the galaxy may be expanding at a similar speed the area covered by expansion is larger. This could be shown with small circles of different radius and comparing area.

[@richardloewen7177]

KUDOS to you for exploring the the present LIMITS of evidence !!!

[@WilliamAArnett]

Lt. Cmdr. Data : Captain, the most elementary and valuable statement in science, the beginning of wisdom, is, "I do not know".

[@curtistrudeau5059]

Remus: Hi Fraser, is it possible that gravitational waves whether individually or multiple interfering with each other are responsible for some of the gravitational lensing that we observe?

[@jensphiliphohmann1876]

39:35 I think we will address the problem of solar flares - a kataklysmic power failure and some million deaths due to the mayhem later.

[@rogerdudra178]

I would answer the same question as you did. I don't know.

[@ReinReads]

Smaller KZbin science channel to check out is Kyle McCaslin neat astronomy and nature photography & stuff. Some might remind you of the fauna on Victoria Island.

[@aetoski8724]

I love your videos so much Fraser... I am considering Computer Science Masters after skirting around the outside of it for a few years now. I have a degree in GIS and Analytics (machine learning, neural networks, LLM etc.) If I wanted to get a job in the space community, do you think a degree in computer science is the best route in 2024? I understand that is a broad field... but i'll take almost anything.. I hate business, and I have had a lot of health issues (on disability) prohibiting manual labor.

[@alleneverhart4141]

I like the way Neil Tyson says it: "Nobody knows" - which sort-of challenges the listener to go find out and report back.

[@mikeullrich9792]

In Cheleb, the part about energy transfer from space, you mentioned a Lunar satellite that could beam microwaves down to the rover in a crater. Couldn't you do the same idea with less complications if the rover had solar cells and the satellite was just a mirror?

[@terrillfloyd]

I would like to know all of the lunar landings.Why they never show the rover being pulled out of the lamp and set up

[@jaydonbooth4042]

I think the main benefit to having a colony/base on the moon would be the same reason why people want to settle Mars. Humans could survive there and continue on for a long time, and I think a country would like to know that no matter what happens on earth, their country will still exist on the moon. And you don't have to technically claim or annex the moon to control it. Once you have a base in or near one of these permanently shadowed craters on the moon, it's essentially yours, nobody else will try to take it from you unless they decide it's worth taking by force some day. And so if the main benefit is a sustainable colony, the thing people could be fighting for on the moon would be these water ice reserves. But it'll be a long time until that kind of thing happens on the moon I'm sure. But humans will certainly bring our wars with us wherever we set up shop.

[@richardanderson1988]

The series For All Mankind illustrated one scenario where there could be warfare on the moon. So the answer is when hate + stupidity + weaponry reach a critical mass.

[@NovaDeb]

Don't forget pride in arrogance. You are absolutely right!

[@JKKoneofakind]

Note: Forgive me, this comment went from a hypothetical scenario for lunar war, into a whole pitch pertaining to the future of humankind. The logistics would be a nightmare, and the consequences so severe to Earth-bound investments, you'd expect outposts off-Earth would primarily stay out of any terrestrial conflict unless they wanted to be completely obliterated. That being said, there is a very distinct scenario I can see playing out in the near-long term that could bring serious war to the Moon and a few other astronomical bodies. Something we could begin today actually, we have the tech for it, there are just a few international treaties and a significant up-front cost to getting started that are in the way. Off-World Colonialism. Right now, gravity is our problem. The Moon, Mars, these are cool goals, and there's a ton we could do there, but long-term, inter-generational habitation is extremely difficult to accomplish, and not really a goal we should be having. Instead, we need to solve the gravity problem. Long term exposure to Zero-G is extremely harmful to the human body, vastly limiting how long our astronauts can be off-Earth. Rotating habitats are a potential solution, and if we can get one running, a single experimental space-station as a proof-of-concept to test the short-term and long-term effects of centrifugal force as a substitute for gravity. In theory, a rotating habitat can extend the length of time an astronaut can be in space without serious consequences to their health. This means deep expeditions to places further out, such as Mars or Ceres becomes far more feasible. If all works well, we can move onto some more serious experiments regarding reproduction in substitute-gravity environment. If (Big if) large mammals can acclimate to environments inside rotating modules and reproduce safely, suddenly our options for the future of space expand infinitely. All the universe becomes open real estate, and the supply will vastly outweigh the demand for several tens of thousands of years, even if we got started right now. That begins the race for the Asteroid Belt. Within the belt, there are millions of asteroids big enough to use for rotating large habitats. Once governments and corporations of Earth realize this, a whole new kind of race is on. The moon used as a near-Earth staging ground, Mars and it's orbit used for resource extraction and mass production of goods required for stellar expansion, and Ceres as another resource extraction site (water, and such) that doubles as a central hub and staging ground for Asteroid Colonies. If stellar colonies like this become a crucial factor in some future war, striking strategic interests on the Moon, Mars, and even Ceres would be fairly crucial to the war efforts, at least in regards to off-world affairs. Unless facilities are buried deep underground, (and even then), they are likely to be obliterated in any exchanges. We won't be exporting man-to-trench warfare on the moon, rather, whatever the inevitable evolution of the current drone-warfare era we are seeing develop. No romantic person to person fighting, rather, outposts bombarded with strikes from absurd distances rolling d20s to see if their anti-weapons systems can hold out. I'm so sorry, this comment got out of hand.

[@bigianh]

The value in going to the moon and mining resources is the ease that these can then be placed into orbit. Institute Resource Utilisation will mean we can produce Fuel and Oxygen on the moon plus other resources. Worst case being able to send regolith into lunar orbit to use for radiation shielding (Cheleb)

[@phaedrus000]

I thought momentum is what causes the flattening in the first place. Isn't it like a figure skater's arms? So why would less momentum result in flattening?

[@mshepard2264]

that is part of the effect but there is more to it. I think collisions are important so that it collapses in to a single orbital plane rather than many.

[@TheSkystrider]

I still think engineers can make a rover survive a lunar night. Insulation + energy source dedicated to maintaining a certain temp. Should even work to let it all freeze and then when the sun comes back, this kicks off a switch that does a chemical reaction form of heat to warm up the battery (like those chemical hand warmers). Just really doesn't seem like a problem even remotely approaching all the other problems involved with putting something in space.

[@omardavivarela]

Nimbus!

[@kimepp2216]

I think the value of a moon base would be to create a collection of observatories powered by nuclear reactors. It would be a training ground for putting research bases on Mars and perhaps other solar bodies.

[@rogertulk8607]

[nimbus] Supplementary question mr. Speaker. as space time expands, any unit of space-time must expand accordingly. so if a spacetme expands to 2 cubic metres of space time the density of the universe must decrease. But if the amount of virtual energy her unit of space-time remains the Same wouldn't this increase the 'pressure' of the virtual energy and result in an increase in the expansion of space?

[@RagaarAshnod]

Fraser for President ❤️

[@frasercain]

Canadians can't run for US President. :-)

[@ophelia1867]

I have a thought for you... why do all 'spaceships' all seem to meet the same side up, in non-directional space? my theory... solar dorsal preference. The sun/star is always up. Planetary life tends this way, but it would also be cheaper to put all solar collection and armour against flares and radiation on one side of a spaceship. The '"top". Got any thoughts on this fun little theory?

[@hervigdewilde3599]

I guess any lava tubes on the Moon are going to be permanently chilly too? So I wonder if they retained any water...?

[@ketturi]

Would it be possible to use Moons huge temperature difference as a power source? Store heat into mass during days, and release it during nights, keeping sensitive things in narrower temperature range, while using the difference to generate power. I was thinking that probe could drill into regolith, as launching needed heat storage capacity would be too expensive, and push batteries and electronics into the bore hole, where temperature swings would be more tolerable and it would also provide some shielding and provide also interesting possibilities for scientific missions.

[@frasercain]

Yeah, there are some cool ideas here on Earth that store heat in sand. I'll bet that would work perfectly well on the Moon.

[@NullHand]

Would work even better on the moon, because without any atmosphere, just wrapping a shiny tarp around a tank makes it a vacuum dewar.

[@Michel613]

Andoria

[@sjzara]

A question: I loved the discussion of using the Sun as a gravitational lens. However this looks like it will take a lot of time to get to the gravitational focus. Would it be possible to use less massive objects in the Solar System as gravitational lenses: what about Jupiter?

[@frasercain]

They're much worse. You'd have to get even farther

[@Smo1k]

The lack of other interaction between "dark matter particles" than the gravitational rhymes with neutrino. The distribution itself, like there was no neutrino production to speak of, until there suddenly was more invisible mass than visible... That doesn't rhyme very well at all with anything I can think of.

[@NoahSpurrier]

Although dark matter only interacts through gravity one would think that it would also be pulled along with normal matter and eventually follow along with the disk of a galaxy.

[@KarelGut-rs8mq]

No. In order to contract, in any dimension, there has to be a way to bleed away momentum. Dark matter lacks such a mechanism.

[@JKKoneofakind]

"Is there life in the Universe?" "We don't know" .. Meanwhile on Earth: Life

[@AndersWelander]

I like the idea that there could be several types of dark matter particles. Imagine if planets and life can also form among dark matter particles. Imagine if there are several sets of mutually invisible sets of dark matter particles. Could anything be said about the chance for that? And how do I know that there isn't some dark matter alien sitting next to me right now?

[@DrDeuteron]

I do like the parallel dark universes idea, but o think is ruled out. A dark 👽 would have to be sitting on a dark,planet, which would have gravity that we don’t see.

[@mickmacy6161]

Janus

[@caerdwyn7467]

Aeturen Given how oversubscribed major space-based observatories are (especially those capable of observing wavelengths blocked by atmosphere), would it make sense to launch a small constellation of "almost-Hubbles" that with modern tech should be much cheaper and more compact than Hubble etc.? A bunch of 10-million-dollar sub-meter-class instruments should greatly increase data gathering and provide more opportunity to research organizations,

[@KarelGut-rs8mq]

"Modern tech" doesn't change the laws of the universe. If you want to see what Hubble sees then you need a mirror the size of Hubble and and a focal length the size of Hubble.

[@marknovak6498]

A solar panal in space would deliver maybe one watt to a final destination a for every 100 watts generated in space based on my back of the envelope calculations.

[@KarelGut-rs8mq]

Not to mention that they would have to be placed in low earth orbit to even be able to transmit to the earth and thus would experience night and day just as down here.

[@PSwayBeats]

Buddy you're a KZbinr You do have a reputation to protect

[@Allan_aka_RocKITEman]

Fraser: I _do_ prefer vanilla ice cream...😊

[@micyclebicycle]

Fraiser do you prefer strawberry vanilla or chocolate ice cream

[@MrMelonMonkey]

What dimensions and power output would you expect from a electromagnet positioned at L1 to enhance magnetic shielding of earth against solar flares? is something like this actually plausible?

[@terminusest5902]

Solar sails to Oumouma is extremely difficult for solar sails. And combine multiple technologies. Timing is extremely fine. Command, control and navigation will be very difficult. Actually landing on the rock is far more difficult.

[@frasercain]

Absolutely. Flybys are one thing, landings are something else entirely.

[@johnfairweather2032]

I think if people knew it was a rock, then they wouldn't be so interested.

[@scottpayne4756]

VULCAN: Matter responds to itself via the Higg’s Field. Dark matter(dark gravity) is made of the same stuff without having the same recipe because gravity waves originating from black hole mergers centered in galaxies prevent it from occuring at those distances from the center of any given galaxy. As trees can grow happily up to a certain elevation on a mountain, beyond which the atmosphere can no longer provide for tall trees, a similar operation occurs when gravity waves disturb near massless particles. If they are too far away and too widely dispersed, nothing much can happen other than just having gravity, or the ingredients for a tree(star) but the Higg’s field isnt strong enough for anything but the mass to do any work.

[@scottpayne4756]

Not a question just a hypothesis with no math or physics knowlege, just observations and trying to make connections that may not actually have any correspondence.

[@MauriceFiorenza]

As it has been said, I don't know. Yet, when Infiniti may be involved mathematical probability says maybe you should know.

[@e.matthews]

"I dont know" is often the only appropriate answer. Think about our ignorance pre-Kepler. Think about the most recent discoveries regarding Hycean worlds and rogue planets. Think about amino chains found in dust clouds... We don't know, but we can be certain that we're in for many surprises. I can't imagine they will lead us to a sterile universe.

[@vturiserra]

0:58 121 ºC is equal to 250 ºF, and 250 is a round number. Is it a coincidence and the temperature of the sunlit parts of the Moon rise to 250 ºF exactly, not one degree more, not one degree less? Or is it an aproximation and then it would be better to say that the temperature rises to 120 ºC, and not exactly 121 ºC?

[@Anonymous-yp7zt]

Why can't we use atomic clocks to build a visible light interferometer?