Q&A 39: Galactic Escape Velocity and More... Featuring Astronaut Terry Virts
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- Опубликовано: 17 окт 2024
- In this week’s question show, Fraser explains why almost everything in the Solar System is spinning in the same direction, is there a limit to how massive black holes can get, and do galaxies have an escape velocity?
In this week’s question show, Fraser explains how astronomers measure the spin rate of black holes, other uses of gravitational slingshots, and why everyone is talking about Patreon.
Check out Terry Virts View From Above
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Hi Fraser. You, Isaac Arthur, and John Michael Godier are the Holy Trinity of RUclips physics and astronomy videos! Love you guys! QUESTION: if a super massive black hole which was ejected from its home galaxy were on a collision course for us, would we be able to detect it? Not just "in principle via its grav lensing," but would we actually know it was coming if it was in fact coming right for us? Or would it catch us by surprise because we're not really looking for it?
You deserve way more subs man. Enjoy the content and appreciate the time you take to make these videos.
Thanks a lot, tell your friends. :-)
Thank you for your answer! You even named the video after my question - I'm honored!
Keep making this great content, you're doing great!
Your answer to Josh Magpoc's Zero-g question really helped drive home the point that only freely falling reference frames are inertial. It's just awesome to think about.
I LOVE these Q&A shows! Awesome to have an Astronaut answer the questions too!
when I grow up, I want to be like Fraser
you want to live in the forest ? ;)
I've lived in forest most of my life, I am referring to Fraser's attitude & presence that affects those around him.... it really is just a joke & compliment to Fraser
Other than the occasional interjection of his religion in his answers, I like Fraser all right.
I have never seen an, "...interjection of religion in his answers...". Now, go to Smarter Every day if you want to get your panties in a twist watching a science video.
Ok. Now we need an episode about cooking pasta over lava.
That would be a llama drama.
Could we use alcubierre drive technology to bend space in front of a spacecraft to protect it from interstellar debris?
Hello Fraser. I love your channel. I have a question. In your videos you have forests etc in the background. Is it your home? Like do you live in a cabin ( or bungalow) in the woods? It is so beautiful. Also I would like to know if this place is in America or Canada.
I live on Vancouver Island, in a small town called Courtenay. No, I live in a regular house, we just have forests all around us. :-)
I never saw the results of your poll but I’m glad your not making 10 minute videos, the longer the better! If some people want to tune out early let them, but I love the depth and detail of longer videos. Best regards Fraser.
Great Q&A as always! Never boring... and I personally think Canada is one of the best country you can live...!
Thanks, I'm glad you're enjoying it.
thankyou for everything you do!!
Totally Cool video..great explanations is super too..excellent job thank you so much..
Dear Fraser, I am not an expert, but I think you got it backwards. If you put two plates close enough, they will actually be pulled together. There is a pressure from virtual particles from both sides of the plate, but inside not every wavelength is allowed due to space constraints, so less particles and lower pressure.
en.wikipedia.org/wiki/Casimir_effect
You're absolutely right, I got it backwards. I'll correct it on the next QA.
Thank you Milan. That is a pretty simple concept to mess up. Makes you wonder what is Fraser's source of 'knowledge'.
It is simple if you learn it properly. Fraser is a journalist and he probably heard about it once and some time ago. There is no way one can do everything right all the time. His reach is extremely broad and he does not have large team of people proof checking every small sentence he said. Plus this questions are partly improvised so he might add this at the last time without double checking... I think he does research on his talks from a lot of sources, mostly public ones, but he does very good job in condensing then into short, entertaining videos. He is not researcher, but that is good, because he can devote his time to paint broader picture.
What are your top 3 funniest comments on your channel this year?
If Venus didn't have a collision powerful enough to give it a magnetic field, why is it spinning the opposite way to everything else?
One viable theory is that, just as Mercury orbits/rotates w/a 2:3 gravitational resonance, such a resonance (w/the Sun particularly) may have preserved Venus' axis of rotation while gradually slowing its formerly prograde rotation & eventually turning it the other way. Neither this nor the impact theory can be "confirmed" w/out further evidence however, despite the popularity of ascribing the phenomenon to such an impact event, the evidence for other such events around the solar system notwithstanding. ^_^
almost the same thought i had
Ender Skies Ugh, why would I even bring it up? The scenario I cited above certainly doesn't rely on it.
www.researchgate.net/publication/11883042_The_four_final_rotation_states_of_Venus
i could explain but it gets complicated . short answer part one , the magnetic field is not directly related to its orbit or spin , part two it could be spinning a different way because of a past collision or because it did not form in our solar system . the long answer has to do with gravity , magnetics and lagrangian points and how those act as the fluid dynamics of space in a ways ...
I think I've seen videos of the shadow of Venus' atmosphere and it actually IS constantly being blown away by solar wind. Might be the extra weight of CO2 that has made it take longer? Just a guess about that "why" part, though.
If the moon creating impact also caused our magnetosphere, wouldn't you agree that is a huge great filter for intelligent life and a strong solution to the Fermi paradox?
The virtual particles will push the plates together not apart due to the Casimir effect.
Yeah, I totally borked that. I knew it too, but got it backwards.
Even without knowing the name, just using the socratic method could lead one to this obvious conclusion. C'mon Fraser.
Hey Fraser! Hope this question makes to your Q&A video this time.
Light movers at lightspeed regardless to the observer, be the observer remains motionless or in motion. So what an single photon (running in the same direction) will look like to an electron moving at 99.999% lightspeed. Will the electron still see the photon pass by it side at lightspeed?
Yes, the photon still moves at light speed in that electron's frame of reference.
Yeah, an electron would see another photon moving at light speed, no matter what. And this is the point, why Einstein came up with relativity.
Fraser Cain Thank you... It will be great if you can explain this in your next Q&A video... Thank you
Great vid. Thank you.
I applaud you for your cautionary and skeptical view of human reproduction and child development off of Earth. Too many people who are beguiled with notions of human space colonization lack such caution and skepticism.
Jurassic Park once said: _"Life finds a way."_ - In other words, we would build a huge Centrifuge in space and have scheduled visits. ;O)-
Absolutely, there will be Safeways in space. But if you are going to have Safeways, complete with centrifuges, autoclaves, microwave ovens, sit-down hairdryers, and mannequin-accoutered store fronts, that is a different story than the one we are being sold by some at present.
To put it another way, and perhaps less cryptically: our next step should be increasing the self-sufficiency of the ISS with a farm, to provide a baseline for the many years of proof of concept necessary to show that a 90% or perhaps even 99% self sufficient off-Earth habitat is doable and "we" understand what it entails. The spinning thing, or rather the whole habitat module spinning, would be another big step, but if you are going to do that, why even bother with a "shanty town" ISS design in the first place? ISS could provide a decent base camp from which to get the first true space station built, but long-term (as Fraser has pointed out) its design is insufficient for protecting its living occupants outside the Earth's magnetosphere.
The tech is to old on the ISS now. Also, we have a planned space station and a moon station (via several avenues) so building a pseudo gravity wheel isn't far behind. As for Mars, the first plans are to have _"brief"_ stays on a rotating schedule - 3 months out, 6 month stay, 3 months back. That is until we have proper equipment to handle longer stays. Totally doable and well worth the effort. ;O)-
It seems to me that number one intermediate priority is off-earth resource harvesting and manufacturing. Bump a great candidate asteroid (or two) into near Earth position and begin to mitigate the need to bring up anything out of Earth's gravity well; except the initial supplies/soil/seed/water and people and sufficient quantities of other resources to 'top off' those being mined/grown. With the proper habitats up there (somewhere . . . moon, Lagrange, Earth orbit, whatever) which achieve a high-degree of internal self-sufficiency and enough materials easily at hand, then our journey into being a Multiplanetary Species can begin in earnest. If this was Elon's vision, I'd be his most outspoken advocate.
Within this framework of what I consider to be a sensible entrance into interplanetary colonization, I don't see a role for Mars. It is unnecessary and serves primarily as a PR device and fantasy. There is one thing that it is worth sending people to Mars for, but in truth even that will be better achieved once near Earth space colonies are well underway: exploring its caves. Apart from some of the outer solar system moons under surface milieu, those Martian caves are likely the best candidate in the solar system for xenobiology. Probably nothing anywhere near eukaryotic, but simple organisms perhaps. Discovering bacteria-like organisms in Martian caves could revolutionize biology and life sciences in general, and I don't think robots will be up to the task of exploring caves for a long time.
Hi Fraser I have a weird question for ya, ok so if a super massive star explodes "near" our corner of the milky way and a small rock from said super massive star say the size of a golf ball and its weight is that of a million tons give or take a ton and it falls into our atmosphere like any other chunk of space ice, rock, iron. Do you think it would burn up in the atmosphere or colide with earth and cause allot of damage or just sink into the planet and get absorbed by our planets core do to its density? Thanks!
Hi Fraser ! I have a question : When we are in orbit, it is similar to falling endlessly; but the earth is falling into the sun, and the sun into the center of the milky way; we are just too rapid to fall in them right ? can we consider the entire universe falling towards something ? Which is ?
That explanation of orbits is a metaphor. The actual motion is (roughly) elliptical.
But at the largest scales, no, there's no overall center. The galaxies form up into gravitationally bound clusters, but the clusters don't orbit anything.
King: The Great Attractor! Not making up that name. Look it up! It is a gravitational anomaly in the middle of the Laniakea Supercluster. As a point of reference, we are in the Virgo Supercluster, many light years away.
Please answer my question: is there such a thing as a binary galaxy in the same way a binary star system works or would all the stars from one galaxy just get pulled together with the larger galaxy in a single massive galaxy?. Therefore could Andromeda not swallow up the milky way but pull it into orbit like a moon? Thanks for your time!
I'm sure there are binary galaxies out there. Two galaxies orbiting a common center of gravity.
Thanks for answering! My son was hoping it would be like when Superman flew round the Earth and started it spinning in the opposite direction and time reversed! 😁
i like how you answer questions totally unrelated to space .. like difference in pronounciation or fraser/frasier difference :)
I try to mix it up. :-)
Hi Fraser, I have a question.
Why don't we build permanent habitats on moon, where it's so much closer and easier to reach first to gain experience with the whole colonization idea before planning for mars?
Neptune's moon Triton is a significant departure from everything spinning the same way. Probably a captured Kuiper Belt Object. The wild side effect of Triton's retrograde motion is that it's very slowly spinning into Neptune as it's being pulled by tidal forces.
Assuming all other variables/properties remained the same, if the Earth were spinning opposite its current motion, the same thing would be happening to our Moon as well: instead of spiraling away, it would slowly spiral in. =D
Hello Fraser, I have a question, not sure it fits your content but what a hell.
Can we take the fact that particles described in quantum mechanics seem like they are not being "rendered" in unless looked at as proof that we live in a simulation? and your thoughts on the double slit experiment that experienced reverse causality.
Thanks! and wonderful content like always!
Is it possible that somewhere out there, there is an answer show with my answers and yours questions?
A very good movie called 'The Space Between Us' deals with the idea of a boy born on a mars colony, coming back to earth in his mid teens and having to deal with some significant health issues. A great watch with one of my favourite actors, Gary Oldman.
yeah with the beautiful brittany Robertson, sure i'll watch it, ty !
I have a question. Could a black hole somehow contract space time and for example, could a really massive one placed between galaxies somehow prevent the continuous space dilation of the universe and prevent them from going further and further apart?
The black hole could pull the galaxies with its gravity, but I can't think how it would do anything beyond that.
11:48 Casimir effect actually pushes the plates together.
I know I know, I totally flubbed that. I'll correct it in the next QA. D'oh!
Total nit but it sent me off watching more videos on the effect :D Thanks!
First time question.
It’s accepted that in black holes there becomes a point where not even light can escape. Then they “evaporate” with Hawking radiation. My real question is once a black hole evaporated sufficiently for photons to escape what would it look like?
Why is there an upper limit for how massive a star can get? And why aren't there any massive stars that can go past fusion with iron? I understand that particular fusion is endothermic, but the elements that can be fused from iron, aren't fusing those going to be viable?
Beyond a certain size the stellar winds blowing off it are so strong that new material can't fall onto it any more.
Paul M. Sutter has a great video on the last minutes of a star in which he breaks down the processes within the star pretty well. It's not exactly on topic, but I thought it might help :D
Yes there is an upper limit. When the mass of the star is so intense that the liberation speed is equal or superior to the speed of light. At that mass, a star can not send photons away; its own gravitationnal forces keep photons prisonners. Yes iron fusion is endothermic, so it cannot give energy to the inner core (and keep the energy inside). Then the gravitationnal forces will win the battle, and the star will collapse on itself.
Just add a neutron star inside the core of another star to fuse all kinds of funny stuff :)
Good Job Boy !! Keep it up
Hey Fraser. Is there some reliable method of detecting exoplanets that have a long orbit period? If I understand correctly, the transit method isn't very good for objects like Neptune that have a very long orbit period. Is it possible that we've missed a lot of exoplanets in the Kepler data that are further away from their stars due to this?
0:44 Uranus has a retrograde rotation as well as Venus.
Good point. Fraser & I have gone back & forth on why you can't have Venus (or Uranus, for that matter) BOTH tipped over AND rotating in retrograde. ^_^ But regardless of that, the motions of Venus & Uranus (among others) still prove the point he is making: SOMETHING had to have happened to these bodies for their rotational motions to be so clearly out of alignment w/the rest of our system, and thus from where they likely were when they first formed.
Question - I have not been able to find an explanation I can understand for why spring tides seem to happen at roughly the same time of day in a particular location. I wondered if this was just confirmation bias but it appears not to be. Thanks very much!
Fraser - Quick question. I can't recall the details of when, where, or how I heard this but I'm certain I once heard a credible scientist on TV state that if all of the matter in the observable universe was compressed together, it could occupy the area of space between our sun and the nearest star Proxima Centauri. Have you ever heard anyone make this claim? I'm imagining this was the scientist's position before the number of galaxies in the observable universe was recently revised.
I haven't heard that, but that sounds plausable, we're all mostly empty space. That up-estimate of galaxies didn't change the total number of stars, just the more galaxies with less stars in them.
Here's one for you. I was just researching how small you would have to squish down the earth to make it a black hole. Apparently the size of a golf ball will do it just fine. But that got me thinking. How would you do the squishing? I was trying to research how dense we could make an object, I was thinking like a big Hydraulic press and a steel ball. What kind of pressures would it take to make that steel ball take up less volume? Or can we just not do it?
Infinity space gives me the chills
The Voyager 1 spacecraft was reported to have recently left the solar system. However, most news organizations and science Outlets are reporting that Oumuamua will be in our solar system for the next twenty thousand years. There is no standard for how big our solar system is, or at least the extent of its influence, is there? Please help.
well, there are several different boundaries you could consider "the edge" of the of our solar system. The edge that Voyager passed is the heliopause - a place around the sun where the pressure of solar wind cancels out with the pressure of interstellar medium.
Another boundary you could define is distance at where gravity from the sun weak enough that the gravities of extra-solar objects become dominant. This is effectively an area where you can expect a planetary body to be able to orbit the sun instead of flying away or effectively jumping to other star system. This is the outer boundary of the oort cloud. It is incidentally also a distance where you can no longer reliably find the sun on the sky merely by finding the brightest star.
KohuGaly thank you for your answer, but it is exactly what I Rage Against. I swear, but cannot prove, that in the last 10 years the news has announced that Voyager 1 has left the solar system three separate times. And the best I can tell, at its current position anyways Oumuamua is going faster than Voyager 1. 45 + years to get out of the solar system does not equal 20000 + years. So my opinion is, the difference is the headlines. That includes the scientific community. It's a neat headline, that Voyager has left the solar system. Is it need headline that the asteroid won't leave the solar system for 20,000 years. I got an idea, how about the truth.
well... asking where you have to go to leave the solar system is kind of like asking how high you have to fly to leave earth's atmosphere. Depending on who you ask, ISS is either in vacuum of space or in the thermosphere, which is not even the top layer of earth's atmosphere yet...
Mark Kromeke I definitely understand the frustration. Part of the problem w/Voyager was that for many months the readings fluctuated, as though it were crossing out of, then _back into,_ the part of space still directly affected by the solar wind. Eventually scientists determined that these readings were evidence of the interstellar medium pushing back against the heliosheath during times of lower intensity solar wind, changing that boundary's location in space & vice versa. Since then, Voyager has stayed consistently in the region dominated by the interstellar wind, and as such is said to be in "interstellar space."
If it helps, think of it like the varying stages of swimming out to sea: standing on the beach is one thing, but if you're wading deep enough that water is always at least over your ankles, are you "out to sea?" Have you "left the continent?" Right, ok, probably not. =D But what about if you walk out far enough to consistently be able to float? What about swimming past the first row of big waves, or past the last row of sand bars? What if you swam out halfway to, or just inside/just outside the edge of the continental shelf? Is that far enough, or do you have to go all the way past where the continental slope meets the abyssal plain before you've "actually left the continent?" You see the issue.
And yet, if you're on a cargo ship that's just left port in Singapore on your way to Los Angeles, chances are you think of yourself as being "out to sea" almost as soon as you've left the harbor & are subject to the winds and currents of the "open ocean." In short, it basically just depends on one's point of view, & what you're most concerned with... and, sadly, which headlines will generate the most clicks while still retaining some semblance of technical accuracy. ^_^;;;
Your answers are great. I really like the ocean example. very well-thought-out and well put. Also the ISS example is very good as well. I have actually heard a scientist say that the atmosphere of Earth can be detected well past geosynchronous orbit. But the discrepancy in my mind is much greater than that. When Voyager 1 cross Neptune's orbit, they said it left the solar system. That was a headline. looks good doesn't it? And then somewhere after that about 10 years ago, they said it left the solar system again, it's good headline. Then a few months ago it left it again. But then The interstellar asteroid isn't going to leave the solar system for 20000 years. This is not a harbor, or low earth orbit. Let me present an example if you will, I live 100 miles Due West of Chicago. I tell some people I live outside of Chicago. I'm stretching the definition of little bit but it's plausible. The difference between Voyager 1 being out of the solar system now and Oumuamua leaving the solar system in 20 thousand years, is like me saying that I live outside of Tokyo.
Hey Fraser. You talked about supermassive black holes kicking out other black holes from other galaxys. The question is,why did they kick them out instead becoming one and more powerfull supermassive black hole? Should'nt the bigger supermassive black hole atract the smaller one to itself and after some time ''eat'' it?
What do you think about putting up a giant sail type object in a retrograde orbit to serve as a junk collector for LEO? It seems like it would have greater chances to encounter space junk and the resulting collisions would slow down their orbital velocity enough to hasten their demise.
11:48-11:55. No, the plates will experience an inward force, tending to bring them together. Vacuum fluctuations exerting pressure on the outside faces of the plates occur throughout the whole spectrum, but between the plates there is an upper limit on wavelength (or a lower limit on frequency) because plates prevent the longer wavelengths. So there's more pressure pushing the plates together than there is pushing them apart, meaning that the gap will close.
Oh yeah, I know I got that one totally backwards and corrected it on the next one.
Hey I'm new but ive been binging ur qna's. What is so hazardous about space? Gamma radiation? Is the iss not a big faraday cage? Bring Todd back! Love seeing him here, Anton too
Is it true that the centrifugal effect of the Earth spinning reduces the gravitational effect at the equator and by doing so causes a significantly measurable reduction in a person's weight?
Q: i was always wondering, how did we measure that universe is 13.7By? knowing that earth is about 4.5By, so 4.5By has already passed, and all that light during this time is missing. thanks!
Hi Fraser, what if you were to dump a lot of iron (or other heavy elements) into a star? If enough iron sank into the core, might that not displace enough fusible material to trigger a supernova?
I'm wondering if we could solve the low gravity issue by arrificially making our bodies “heavier“. In other words wouldn't a suit that would make you weight as much as you would on Earth at least keep your muscles strong? Obviously not blood or other body fluids but it would be better than nothinh I guess...
Could that even work???
As you said, this would help your muscles and bones, but not your organs. It would help, but not fix everything.
At 11:50 you mention an outward force. I've always learned thls force to be inwards, because between the plates there are fewer virtual photons as fewer possible waves are possible. According to Wikipedia this is called the Casimir effect.
I watch your videos while playing games recently I was playing warframe and on Venus there was snow could you explain what we would have to do to make it a white Christmas on Venus?
You'd have to set up a sunshade to cool down the planet. Once it got cold enough, the CO2 in the atmosphere would fall like snow. :-)
Another way to tell an American apart from a Canadian:
American : "awww, aren't they cute, they have Mounties and sled dogs."
Canadians : "we kicked your ass in 1812."
I loved the part about differences in Canadian and American pronunciations
Fraser, HIGHLY recommand you read "Falling Free", it's about genetically modified humans with 2 sets of arms, second set where legs used to be. Very good story. New species is named Homo Quaddicus
If there is no center of the universe (or, alternatively, if every point in the universe is the "center" of the universe) doesn't that mean that there is also no edge of the universe? However, if there is no edge doesn't that necessarily imply that the universe needs to be infinite? How is that compatible with the estimated size of the visible universe (~93 billion light years) and the size of the much much bigger yet still finite universe beyond our light cone?
Passsta isn't so bad. I'm not dyed in the wool for pahhsta. It's a tomato, tomahto kind of thing. But "lava" should definitely be lahhva, to keep it distinct from the first syllable in lavatory.
It's a West Coast thing apparently.
Love the videos! Also, just started listening to Astronomy casts :) Question: has the probability of the killer asteroid hitting the earth increased significantly as we found a ‘visitor’ from interstellar space?
Doesn't Casimir effect show attraction of the plates in vacuum? 🤔
Yes, I totally borked that. I'll do a correction.
If I was to get binoculars of the sort you recommend as a starting point for star gazing, are there any things (objects, phenomena etc.) that you would recommend as interesting things to go look at to begin with?
Love the stuff you do and been working my way through a lot of your videos recently, keep up the excellent work!
Anything you can. Star clusters look great within binoculars, you can see Andromeda, various binary stars, the Moon, planets, etc.
Fraser Cain Thank you for answering :) those sound great
I've got 15x75 binos and I really like them.
Fraser Cain 15x70 seem to be the equivalent available here in the UK but I'm guessing they will be pretty much the same in practical terms
Yeah, anything in that scale is fine. 25x100s are nice but a little heavy.
The equilibrium where the person is held between two earth size objects would be an unstable equilibrium. So you wouldn't float more than a ball could stay still on top of a parabola-shaped hill with a global maximum value.
Sure, you could float around, push yourself off from Earth to Earth, and eventually you'd slide away from this balance point. It's like being in a Lagrange point.
Fraser Cain Yes. The centre of two equal mass objects is the Lagrange point L1 which is unstable. You would eventually float away from the equilibrium since it is a saddle point. L4 and L5 are stable, though.
farside.ph.utexas.edu/teaching/336k/Newtonhtml/node126.html
Relating to solar sails, is the light pressure measruable on larger objects such as asteroids or the earth? If so how has the affected their velocity?
If an object like a large rocky planet breaks up, how quickly is it's gravitational effect on surrounding objects altered and how?
Hello Fraser, my question is about light. Speed of light. What would happen, how our Universe, Earth would look like, when the speed of light would be, let's say, half of current value. What with Laws Of Physics. How our Sun would behave. Would the Gravity (particles) be faster? What would happen to Reason&Cause rules. Thermodynamics. Electrical current. I believe everything would change, but this Universe could support life? Could you please discuss a little - how and what could we observe, experiment - when this one of the most fundamental values be different. Thank you.
Since Christmas time is fast approaching I would like to know if holidays are celebrated in space or not?
Would it be possible to create a binary star system from two separate stars through star towing or a star tractor or any other futuristic way? How about two binary systems into a double binary?
Sure, if you had the ability to move stars, you could configure them into a situation like that.
Hi Fraser,
Love your videos and enthusiasm about astronomy.
I was just thinking about Voyager1 and Voyager2 leaving our sollar system into interstellar space, carrying a message from humanity in them, and it made me wonder:
Suppose an alien civilization sent a similar probe (same dimensions and travel velocity) into interstellar space it was caught by the gravity of our solar system.
what are the chances of our telescopes detect it, and even if they did, how could we even intercept it without destroying the message it is carrying, all that with our current technology.
Thanks and keep up the good work!
How do we know SMB's in extremely distant galaxies have masses equal to billions of solar masses? When we consider the great detail we can study the stars movement around ours, are we able to see other galaxies SMB's in the same way or is there another method?
The "destroyer of worlds" SMB springs to mind in regards to how we can possibly know their masses.
Escape velocity of Earth, ???? Please Help., If i hade a rocket or plane with enough power to travel at a constant say only 200 mph but can go more if needed or less but unlimited power. can i leave earth into space ??? or does it require speed and not power ?? I'm just confused can U please help. thanks
Follow-up to the 0G question: Judging on all stuff in the observable universe that exerts a gravitational force, where would its (referring to the observable universe) "centre of mass" be? Would it be very near to us (in universal terms) and maybe even in the milky way due to the observable universe being centred on us? Or is there vastly more gravitational force exerting stuff in one part of the OU?
DagarCoH There are no center of mass. Center of the observable universe is where the observer is. If it is X-distance from here, its center will be there too, but the observer sees different objects.
XtreeM FaiL I know about the centre of the observable universe. And I don't know where you get the notion from that there is no centre of mass. If you have a certain amount of massive particles in a 3 dimensional space there has to be a centre of mass. I just wanted to know if the universes mass is pretty balanced out (in which case the centre of mass would be pretty near to us, say, in our galaxy cluster) or very unbalanced.
how would you power a spacecraft like the Axiom in wall-e with everyday technology? I'd like to see you try to answer that
How does a black hole boot out another one? Does this work like a gravity assist by satellites ?
What would happen if there was a tear in the universe? Would we be able to see it? Could we escape the universe? Would we even know it exists? Definitely a topic I'd like to know more about!
If the earth was hit by a mars sized object which enabled earths magnetosphere. How come the collision that set venus spinning into the wrong direction wasn't enough to set into motion a similar event as with the earth and moon?
It's an interesting conundrum. Aside from the weird spin, there's actually very little evidence of such an impact on Venus, despite signs of other such impacts occurring around the solar system. Another viable theory is that gravitational resonance w/the Sun (& maybe Earth as well) has not only preserved Venus' orientation (
I figured i wouldn't get a satisfying answer to that thought/question, far less to end up on the next Q&A! lol. However i must thank you for bringing to my attention the alternative theory, which i wasn't aware of previously. Thanks.
Maybe Venus/Earth/Moon are the results of pretty badass collision and Venus got the worst of it tumbling upside down and losing its spin (maybe leaving most of its core merged with Earth's)? O_o
Hey Fraser, the Casimir Effect works the other way round. There are fewer possible wavelengths in between the plates than there are outside of them, which results in fewer virtual particles appearing and annihilating there. The resulting pressure differential forces the two plates towards each other, rather than apart. Otherwise great Video though :)
Right right, thanks!
No problem, that stuff is confusing :D
No, I knew the answer and totally flubbed it. D'oh!
You said Venus must have had a collision hard enough to flip it over and later you said it didn't have a collision hard enough to churn around the insides and keep it's magnetosphere. Can you explain what could have happened where the hit that tiped it didn't mix it like that
Q: what would happen if someone installed a layer of perfectly reflective material between the Earth and the Sun, blocking all light spectrum? It would be dark and cold here, sure, but what about other effects? What about pressure coming from light particles as in solar sail tech.?
My question... Does NGC7603 and its plasma connected companion galaxy invalidate Hubbell's Law?
Fraser. Your top five science related bucket list items?
I've crossed 3 off so far. Solar eclipse, rocket launch, and killer auroras. The last one for me is a bright comet.
Hi I liked it when you listed the q&a's with time marks. Q Can we replicate cosmic radiation here on earth?
Yeah, I just ran out of time. I'm putting them in now.
Hi! What would happen if the Earth and everything on it disappeared while I'm sleeping? Would I continue to orbit the same way or would I fly straight into deep space?
Marco Fantin You would keep orbiting the sun, though you would have a bad time with no atmosphere unless you sleep in a space suit ;)
Your orbit would be slightly different though because of angular momentum from the spinning planet you were recently on (unless you were also sleeping on the North Pole).
Hi Fraser Cain, I would like to know your final judgement on the questionable "Tabby's Star". Would you call it a Dyson Sphere, Dyson Swarm, an Asteroid, Comet Field? Are your hopes up that it's an alien civilization fusion reactoring its parent star/ matrioshka braining an omega CPU? Or do you tend to lean on the side of it being an anomaly James Webb will help clarify (likely?) ?
everything in space is moving, is it possible to put something in space to be completely still, not moving at all?
There has to be some sort of drag that is caused by a body's rotational vector. Uranus' moons orbit at the angle and direction of Uranus's highly tilted axis of rotation.
Q: Solar sails seem really brittle. How can/will engineers compensate for high speed collisions with dust and small meteorites?
Is it possible to construct an ion drive, that uses the rest atmosphere in low earth orbit as Working mass? So you could counteract the loss of impulse due to that atmosphere.
Hi Fraser,
What would happen if two black holes collide? That will happen when our galaxy collides with Andromeda and the super massive black holes will collide so what will happen?
Now that "Transparent Aluminum" (Aluminum Oxynitride) is a thing, being several times stronger than any current glass formulation, when can we expect this to be used in space (the ISS, future rockets, etc.)?
It took me quite a while to get my head around the big bang, its hard to explain and I think past visuals/documentaries have always shown it as an explosion from a single position. The 'Big Bang' also kind of implies this, but now I visualize it as an expansion in all places, we would be a gas molecule (less dense) and the early universe a solid (more dense).
If Mars colony A and B came into conflict, what sorts of weapons would they use? Traditional firearms? Or would they resort to long sharp metal poles to try to puncture suits? I'm sure humanity would easily find a way to kill each other no matter the environment.
Gally no reason to my knowledge that a gun wouldn’t work. It may even be more effective because there’s less gravity and no tangible air friction. They’ll also probably be completely silent.
Gally I'm guessing Luty guns will be used.
sdf3123 Mars may have a thin atmo, but not thin enough to kill the sound.
How close of a flyby by a supermassive black hole the mass of the one in the centre of the Milky Way would be necessary to disrupt the orbit of the Earth around the Sun?
So when the universe was just a little spec did it have the same gravitational field of the universe today of even bigger?
I'm sorry, you likely answered this one before, but what's your educational background? Did you go for a stem degree and later discovered journalism or did you start right off with journalism? And why space journalism (I don't know the proper term, but this one would make you a "space journalist" :D) instead of tech or general science?
How would gravity affect a person on a planet with double the mass of earth, would the increase in diameter offset the gravity increase?
Joe Fernandes:
a_planet = G*m_planet/r_planet^2 = G*(2*m_earth)/(2^1/3*r_earth)^2 = 2/2^(2/3) * a_earth = 2^(1/3) a_earth. So the gravity would be cube root 2 (that is 2^(1/3)) stronger than on earth, that is about 1.26 times the acceleration on earth, i.e. 26 pct. more than we experience here on earth.
Assuming the density of the planet is the same as that on Earth, its radius would be 2^(1/3) times larger than Earth's radius, so that offsets a lot of the extra acceleration due to gravity that you would experience from a doubling of the mass.
I weigh about 80 kgs. On the planet with double the mass but the same density as Earth I would weigh 101 kgs.
question they from what I read the big bang came out of a singularity. They also say black holes are singularity. is it possible we as humans have never seen a black hole explode and inb fact what we call the big bang was actually a singularity exploding? or is it possible the singularity was a plasmoid exploding
Q&A question: If a black holes Schwarzschild radius (size) grows proportionally with its mass, then why do physicists talk about the centre as being a 'singularity' and having an infinite density?
We already know what would happen if the Earth spun in the opposite direction. As seen in "Superman the movie", time would go backwards.
First Cynic - we can learn about the universe and laws of nature from Hollywood also, not only Fraser Cain, they know a lot
Give ilimited time, is possible in the future build a telescope so powerful that it sees the surface details of other star system planets? Or the light becomes so scattering that no amount of technology is able to see such details at cosmic distances? In other words, when we have warp drives and build such telescope far way, we will able to see Earth historical events from centuries ago.
When they run simulations of how solar systems form, how often do you get moons around terrestrial objects? I ask because, if Venus is upside down because of a collision, why doesn't it have any orbiting body? Let alone, a Moon-sized moon.