How do black holes mess with the fabric of time? Time isn't a tangible thing, so how can it be destroyed in a black hole? How do we know what it's like to be sucked into a black hole? Will we ever have experiments in the future to test this? How do we know all of this information about black holes if a human has never been close to one?
Time isn't tangible to us in the way that space is, but that could easily be a limitation of *us*, not of time itself. So under certain conditions it can be stretched and compressed in a similar way that space can.
Inside a black hole and in the areas around them are at extremes of physics the likes of which people have never experienced, so we don't easily have any kind of intuition about them. Physicists have over the years developed a set of equations governing how gravity and spacetime works, and we rely on those to predict what would happen near a black hole, for instance, what it would feel like to fall into one. Maybe we'll have experiments at some point to test the predictions out, but at the moment we can't do that.
But you definitely don't need to be up close and personal with a black hole to learn a lot about it. After all, we know a lot about our Sun and a human has never explored the surface of it (in part because that's another set of conditions we couldn't survive with current technology). But we certainly know it's there from its many effects. Although a black hole is physically very different from the Sun, we can still infer the presence of a black hole from its effects on the objects around it.
I would like to know absolutely everything about black holes and wormholes. I know that there are wormholes all around us but then why can't we figure out stuff about the wormholes? and is negative energy really a black hole? If not than what kind of energy do you think it is?
I'm not sure there are wormholes all around us; there are plenty of theories that state wormholes should exist, but as far as I know we have never actually found one. That may just be because they're very rare, but until we discover one we will have to be content with exploring the equations and the theoretical physics to understand what we might expect their properties will be.
This is a good question, and the answer depends on a few things, such as the size of the black hole and whether or not you care if you survive the encounter.
A black hole doesn't really have a surface; the event horizon (aka the Schwarzschild radius) isn't a physical thing, just a theoretical line where on one side you can escape the black hole and on the other you can't. If you care about surviving an encounter with a black hole, and you have the technology to travel near to the speed of light, then just don't cross that calculated line in space. But be careful: there are scifi stories about people in advanced space ships exploring near the event horizon and accidentally crossing over it without realizing. Because the event horizon doesn't itself provide any surface, or bumps, or alerts, that is actually possible. And once you're inside the event horizon, you're not getting out.
If you don't mind giving up your life to science, well... given the right technology you could probably go inside a black hole and even stay alive for a while on the way down to study what's happening.
Getting the information you collect back to your friends back hole, however, is a different matter entirely. Nothing escapes a black hole, not even light; and the signals we currently send to each other over the internet, a cell phone, the radio, or through space, are all light. So your transmission wouldn't be able to make it out of the black hole, and nobody could ever benefit from your information.
There are people who study possible ways around this, and those are intriguing, but for now it's all science fiction, because we can't get anywhere near close enough to a black hole to test it out with the technology we have right now.
Clearly, I am to young to go on the mars mission, but if I could, do you know what background information about space I would need to know, to survive in such daring conditions?
Actually, I think the book The Martian was a pretty decent primer on what it might be like to live on Mars. Some of the technology described in the book doesn't yet exist, but it's not all that farfetched, so maybe in a not-too-distant future all of that (or most of that; the science isn't perfect) will be possible.
One thing they didn't really cover in the book or the movie is the radiation dose you'd receive on your way to and from Mars, and while on the planet. The Earth's magnetic field protects people on Earth and in low orbit from a lot of nasty solar radiation, but once you're away from Earth you lose that protection, and Mars doesn't have a magnetic field (we think it lost most of its atmosphere when the magnetic field disappeared a long time ago). So anyone who goes to Mars and back is signing up for an increased risk of basically all the cancers, as well as an increased risk of a fatal dose due to a freak radiation storm (they happen relatively frequently but not regularly). Any mission design will prioritize protecting astronauts from radiation, as well as giving them the tools and training they need to survive all the other harsh conditions.
PS - Why are you too young? The NASA Mars missions have a very long timescale, and we don't know how long they may last. If you really, really want to go to Mars, you'll need to be ready and in a position to be selected in 15 years, which means now is the time to start!
Is there a way of telling how many stars there are in the universe, like you can tell the age of a star? Approximately, how big is the biggest star? How small is the smallest? How many stars are born each second?
Sure, you can estimate a star count: first, count all the galaxies. Then estimate how many stars per galaxy!
That's much harder than it sounds, of course. In part that's because the answers to all your other questions depends on what epoch of the Universe we're talking about. Now, 13.8 billion years after the Universe began, we have a pretty good idea that the biggest star is tens of times bigger than the Sun and the smallest is about a tenth of the size of the Sun. That lower limit is based on the minimum size a collapsing gas cloud needs to reach in order for the core to get hot enough to turn on fusion, so that's probably pretty similar at all epochs.
But the biggest size of a star is set by the composition of the gas from which the star forms, because the composition of the gas tells you how the enormous molecular clouds (which are often thousands of times the mass of the Sun in total) will fragment into smaller clumps, some of which eventually become stars. The closer the gas is to pure hydrogen, the larger the clumps can be, and thus you can get bigger stars. In the early Universe, before the early generations of stars had made all the heavier elements and then distributed them back into the interstellar medium via supernovae, stars were bigger because the gas clouds from which they formed were closer to pure hydrogen. Nowadays we've had a couple of generations of stars enriching the remaining gas with heavier elements, so it's easier for certain cooling processes to occur that help with fragmentation, and the maximum size of a star is smaller. The Universe is also a bit cooler overall, so theoretically it might be easier to form stars, but also the Universe is less active, so the shock processes that trigger star formation are less likely to occur. Overall, the rate of star formation in the Universe peaked about 10 billion years ago, stayed high for a few billion years, and afterward began gradually declining (and it's still declining today).
Is there a way of telling how many stars there are in the universe, like you can tell the age of a star? Approximately, how big is the biggest star? How small is the smallest? How many stars are born each second?
Recently, scientists discovered two black holes that were going to come together. How will this alter space time continuum and what will it suck up most galaxies?
Things will get a little strange right near the two black holes, and hopefully the first of a new generation of gravitational wave detectors will be able to detect the ripples in spacetime that will occur because of this, but it definitely won't suck up anything outside its relatively small sphere of influence. The kinds of signals from colliding black holes that gravitational wave detectors are hoping to detect are absolutely tiny, which means that you and I haven't noticed any of the times a ripple from a merging pair of black holes has reached us from one galaxy or another (it's probably not that rare an event).
It takes a star many times the mass of the Sun to explode; the rest will go through some other interesting phases but eventually will become a white dwarf and just slowly cool off and fade out.
There's some good information on the details of high mass stellar life cycles here: http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/stars/lifecyclestarsrev1.shtml
I was reading about how stars can form Globular Clusters that contain millions of stars all in the main sequence stage or already forming heavy elements. The stages of these stars tell us that they all have large masses, so we can assume that they have large gravitational pulls. I was wondering how it is that these millions of stars don't form together into a massive star never discovered before.
Actually, most globular clusters are really old, so most of their high-mass stars have already evolved through their more rapid life cycles and died, leaving behind cores and remnants and black holes. The ones that are still main sequence stars are the lower-mass ones, but it means there's a range of stars in various stages of evolution and with varying orbits. Lots of stars in globular clusters are in binary orbits, and occasionally stars there do collide (those are very cool objects of interest for stellar astrophysicists), but most don't -- even dense globular clusters are still mostly empty space.
If a lot of stars did manage to coalesce in a globular cluster, though, two things would happen: first, because of interactions with other stars the giganto-star would sink pretty quickly (quick compared to the Universe, i.e. tens or hundreds of thousands of years) to the center of the cluster. Second, it would form a black hole even more quickly, because it would have enough mass to do so and because, if it were formed from stellar remnants, there wouldn't be enough light elements left to start fusion and hold up the giganto-star against its own gravity. People have looked for black holes in the centers of globular clusters, but as far as I know nobody has found definitive evidence for one.
Note: giganto-star is not an actual scientific term.
First answer: nope, not really. But what defines the surface of a star? A star doesn't have a crust like the Earth, so you can't step on it -- at some point an astronaut getting close enough might be interacting with the actual stellar photosphere, but even then it wouldn't be like setting foot on the Moon or Mars. It would be like putting your hand in the ocean... if the ocean were 6,000 degrees Celsius and a highly magnetized plasma. In other words, it would definitely hurt. :)
Second answer: if there is enough material co-orbiting the black holes then there might be some interesting magnetic effects that could act like explosions, but there won't be an explosion of the black holes themselves.
We don't know for sure, but we can make very well-informed predictions. This kind of research is in some ways in the realm of science fiction, because we can't test the hypotheses we generate based on what we know of the physics. But as I've heard the UK's Astronomer Royal (Martin Rees) say, first-rate science fiction is better than second-rate science.
Where does all the matter go when it is sucked into the black hole? Also, is there any signs that there are humans or Aliens anywhere out in the universe? Do you think we could ever live on mars in the future?
Here's a situation where the term "black hole" sort of fails to capture what's really going on, or at least what we think is going on. It might be more accurate to think of it as a "cavern" or "chasm" than a "hole", so when things fall into a black hole they end up being compacted at the "bottom", which is analogous to the singularity at the center. At least, we think so. There are theories about objects called "white holes", in which stuff that falls into a black hole falls out of a corresponding white hole. But nothing like that has ever been observed, so it might be more useful to think of a black hole like an infinitely efficient trash compactor.
We haven't seen any clear signs of aliens yet, but I'm keeping my fingers crossed. And I do think we could live on Mars, eventually.
What is the power of a black hole? I am wondering if their is anyway we can measure it's strength and if so what unit would it be in? Also if we could measure black holes power would all black holes have around the same power or would they be drastically different?
There are 3 basic things we measure about a black hole:
1. Its mass 2. Its rate of growth (accretion rate) 3. Its spin
The mass measures how much the black hole warps spacetime and it's analogous to the mass anything else has (it's just much more compact). The accretion rate measures how much mass is falling in, i.e. how fast the mass is changing. With many black holes this is close to 0, but when a black hole is actively accreting mass it's much easier to observe because all the matter around the black hole tends to get very luminous. The spin is harder to develop an intuitive sense for, but it measures the way the warping of spacetime is modified by the black hole having angular momentum. For a non-spinning black hole, the "surface" described by the event horizon is a sphere of a certain size. For a spinning black hole, it can be much smaller and doesn't have to have quite the same shape.
All the physics of black holes scales with the mass, by which I mean that in the computer models of black holes they just leave the mass as a variable, because you get the same answers that you just later plug the mass into to get an actual number or set of numbers for. So in some ways that means all black holes are fundamentally the same, but the masses can vary by factors of 1,000,000 or more, so actually they are also drastically different.
Are there any theories as to where the singularity that caused the big bang came from? I know it's one of the biggest scientific mysteries, but are there any ideas besides the concept of a creator?
The concept of the multiverse is relatively new and is pretty interesting. It says the Big Bang might not be unique, that maybe similar events are happening at random times and creating many other universes. I'm not properly an expert on the multiverse but as far as I understand it, it seems to be random fluctuations that trigger or do not trigger a Bang-like event, and similarly the fundamental parameters inside the universe (like how strong gravity is and how well atoms hold themselves together and how many atoms there are and so on) can be very different as well.
Of course, you can always ask "but what made the multiverse happen?" and so on; there's always a "but what happened before this" question. Some people argue this leaves room for a creator; others argue that a creator isn't needed (and some further argue it therefore probably doesn't exist). I think physics generally is agnostic about it; physicists are another matter!
Why would it have to end just because it's expanding? I don't know of any physics that says it can't expand forever. That's what we think it will currently do, so time won't ever stop, if that's correct.
The Law Of Conservation of matter and energy states that they can not be created or destroyed, but transformed. When matter and energy enters a black hole, because it can't be destroyed, how is it transformed, and where does it go?
This is a great question. A lot of energy is radiated away as something falls into a black hole, but whatever is captured by the black hole becomes part of the black hole -- black holes only grow, and whatever they eat, they keep. We think some black holes have grown in mass (i.e. energy) by factors of a million or more over their lifetimes.
I see this question was posted at the same time as Elizabeth's above and it's very similar; great minds think alike! I'll just refer you to my answer to that one. :)
For now we think they just kind of get stuck there. If you fell into a black hole, then as you fell toward the center you'd eventually get torn apart into just atoms, and then the atoms would eventually get torn apart into particles, and so on... according to our theories at the moment it's all added to a singularity at the center, and the energy/mass of the things that fall in get added to the mass of the black hole.
We'd have to find it first! We have yet to find another world that we've confirmed is habitable. Right now we're only even able to look in our own neighborhood of this galaxy; eventually we may be able to search more of our galaxy and perhaps nearby galaxies... but until we discover some completely new way of travelling through space actually going to another galaxy is not really feasible. For example, even if we could travel at the speed of light (which the laws of physics forbid for humans and spaceships and other things with mass) it would take us 2 million years to get to our nearest neighbor spiral galaxy. So if we want to send ourselves (not just robots or some kind of other self-replicating information carrier) we should probably stick to our own galaxy!
What is Oxford like, in the sense like the atmosphere, the mood, what the place looks like and how people act. Do they always act super serious and only study or do they also do other fun stuff in the meantime?
In many ways Oxford is just like any other university. There are plenty of fun things to do here, and people definitely have fun! They also work very hard, both during the school terms and out of term (there's usually assigned work or reviewing to do outside the terms). Expectations are high and there is a lot of material to cover; Oxford earns its reputation as one of the finest educational institutions in the world. But it's not all studying, and actually the amount of fun the students sometimes get up to is legendary. The people are as varied as anywhere else; there are hipsters and hippies and snobs and poor people and posh people and people whose great-great-grandfathers were Masters of their Oxford college and people who've never been to university before and activists and jocks and people who just want to do the minimum amount of work to pass their degree and people who could spend years in the library or the lab. And combinations of these things and people.
It's also true that in many ways, the Universities of Oxford and Cambridge (sometimes referred to as Oxbridge) are not like anywhere else. The College system started here and continues here in a way that's different from other places that still have it (including US universities that have residential colleges modelled after Oxbridge; places like Yale colleges are similar on the surface, but fundamentally quite different). The architecture is beautiful, varied, and authentic. Oxford has colleges ranging from 753 years old to about 20 years old. There are parks and gardens everywhere, and certainly each of the colleges has its own unique beauty.
Basically, if you watch films and TV shows like Brideshead Revisited and Endeavour and such, there's clearly a stereotype of what Oxford is, and it's not completely wrong, but nor is it completely right. If you come to Oxford as a student or researcher, you can make it what you want. I love it here.
How do black holes mess with the fabric of time? Time isn't a tangible thing, so how can it be destroyed in a black hole? How do we know what it's like to be sucked into a black hole? Will we ever have experiments in the future to test this? How do we know all of this information about black holes if a human has never been close to one?
ReplyDeleteTime isn't tangible to us in the way that space is, but that could easily be a limitation of *us*, not of time itself. So under certain conditions it can be stretched and compressed in a similar way that space can.
DeleteInside a black hole and in the areas around them are at extremes of physics the likes of which people have never experienced, so we don't easily have any kind of intuition about them. Physicists have over the years developed a set of equations governing how gravity and spacetime works, and we rely on those to predict what would happen near a black hole, for instance, what it would feel like to fall into one. Maybe we'll have experiments at some point to test the predictions out, but at the moment we can't do that.
But you definitely don't need to be up close and personal with a black hole to learn a lot about it. After all, we know a lot about our Sun and a human has never explored the surface of it (in part because that's another set of conditions we couldn't survive with current technology). But we certainly know it's there from its many effects. Although a black hole is physically very different from the Sun, we can still infer the presence of a black hole from its effects on the objects around it.
I would like to know absolutely everything about black holes and wormholes. I know that there are wormholes all around us but then why can't we figure out stuff about the wormholes? and is negative energy really a black hole? If not than what kind of energy do you think it is?
ReplyDeleteI'm not sure there are wormholes all around us; there are plenty of theories that state wormholes should exist, but as far as I know we have never actually found one. That may just be because they're very rare, but until we discover one we will have to be content with exploring the equations and the theoretical physics to understand what we might expect their properties will be.
DeleteI was wondering how close humans can get to black hole? Also, how can you study exactly what happens in a black hole?
ReplyDeleteThis is a good question, and the answer depends on a few things, such as the size of the black hole and whether or not you care if you survive the encounter.
DeleteA black hole doesn't really have a surface; the event horizon (aka the Schwarzschild radius) isn't a physical thing, just a theoretical line where on one side you can escape the black hole and on the other you can't. If you care about surviving an encounter with a black hole, and you have the technology to travel near to the speed of light, then just don't cross that calculated line in space. But be careful: there are scifi stories about people in advanced space ships exploring near the event horizon and accidentally crossing over it without realizing. Because the event horizon doesn't itself provide any surface, or bumps, or alerts, that is actually possible. And once you're inside the event horizon, you're not getting out.
If you don't mind giving up your life to science, well... given the right technology you could probably go inside a black hole and even stay alive for a while on the way down to study what's happening.
Getting the information you collect back to your friends back hole, however, is a different matter entirely. Nothing escapes a black hole, not even light; and the signals we currently send to each other over the internet, a cell phone, the radio, or through space, are all light. So your transmission wouldn't be able to make it out of the black hole, and nobody could ever benefit from your information.
There are people who study possible ways around this, and those are intriguing, but for now it's all science fiction, because we can't get anywhere near close enough to a black hole to test it out with the technology we have right now.
Clearly, I am to young to go on the mars mission, but if I could, do you know what background information about space I would need to know, to survive in such daring conditions?
ReplyDeleteActually, I think the book The Martian was a pretty decent primer on what it might be like to live on Mars. Some of the technology described in the book doesn't yet exist, but it's not all that farfetched, so maybe in a not-too-distant future all of that (or most of that; the science isn't perfect) will be possible.
DeleteOne thing they didn't really cover in the book or the movie is the radiation dose you'd receive on your way to and from Mars, and while on the planet. The Earth's magnetic field protects people on Earth and in low orbit from a lot of nasty solar radiation, but once you're away from Earth you lose that protection, and Mars doesn't have a magnetic field (we think it lost most of its atmosphere when the magnetic field disappeared a long time ago). So anyone who goes to Mars and back is signing up for an increased risk of basically all the cancers, as well as an increased risk of a fatal dose due to a freak radiation storm (they happen relatively frequently but not regularly). Any mission design will prioritize protecting astronauts from radiation, as well as giving them the tools and training they need to survive all the other harsh conditions.
PS - Why are you too young? The NASA Mars missions have a very long timescale, and we don't know how long they may last. If you really, really want to go to Mars, you'll need to be ready and in a position to be selected in 15 years, which means now is the time to start!
DeleteIs there a way of telling how many stars there are in the universe, like you can tell the age of a star? Approximately, how big is the biggest star? How small is the smallest? How many stars are born each second?
ReplyDeleteSure, you can estimate a star count: first, count all the galaxies. Then estimate how many stars per galaxy!
DeleteThat's much harder than it sounds, of course. In part that's because the answers to all your other questions depends on what epoch of the Universe we're talking about. Now, 13.8 billion years after the Universe began, we have a pretty good idea that the biggest star is tens of times bigger than the Sun and the smallest is about a tenth of the size of the Sun. That lower limit is based on the minimum size a collapsing gas cloud needs to reach in order for the core to get hot enough to turn on fusion, so that's probably pretty similar at all epochs.
But the biggest size of a star is set by the composition of the gas from which the star forms, because the composition of the gas tells you how the enormous molecular clouds (which are often thousands of times the mass of the Sun in total) will fragment into smaller clumps, some of which eventually become stars. The closer the gas is to pure hydrogen, the larger the clumps can be, and thus you can get bigger stars. In the early Universe, before the early generations of stars had made all the heavier elements and then distributed them back into the interstellar medium via supernovae, stars were bigger because the gas clouds from which they formed were closer to pure hydrogen. Nowadays we've had a couple of generations of stars enriching the remaining gas with heavier elements, so it's easier for certain cooling processes to occur that help with fragmentation, and the maximum size of a star is smaller. The Universe is also a bit cooler overall, so theoretically it might be easier to form stars, but also the Universe is less active, so the shock processes that trigger star formation are less likely to occur. Overall, the rate of star formation in the Universe peaked about 10 billion years ago, stayed high for a few billion years, and afterward began gradually declining (and it's still declining today).
Is there a way of telling how many stars there are in the universe, like you can tell the age of a star? Approximately, how big is the biggest star? How small is the smallest? How many stars are born each second?
ReplyDeleteRecently, scientists discovered two black holes that were going to come together. How will this alter space time continuum and what will it suck up most galaxies?
ReplyDeleteThings will get a little strange right near the two black holes, and hopefully the first of a new generation of gravitational wave detectors will be able to detect the ripples in spacetime that will occur because of this, but it definitely won't suck up anything outside its relatively small sphere of influence. The kinds of signals from colliding black holes that gravitational wave detectors are hoping to detect are absolutely tiny, which means that you and I haven't noticed any of the times a ripple from a merging pair of black holes has reached us from one galaxy or another (it's probably not that rare an event).
DeleteA question that I have is, What is the life cycle of a high mass star and what type of star can explode?
ReplyDeleteIt takes a star many times the mass of the Sun to explode; the rest will go through some other interesting phases but eventually will become a white dwarf and just slowly cool off and fade out.
DeleteThere's some good information on the details of high mass stellar life cycles here: http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/stars/lifecyclestarsrev1.shtml
I was reading about how stars can form Globular Clusters that contain millions of stars all in the main sequence stage or already forming heavy elements. The stages of these stars tell us that they all have large masses, so we can assume that they have large gravitational pulls. I was wondering how it is that these millions of stars don't form together into a massive star never discovered before.
ReplyDeleteActually, most globular clusters are really old, so most of their high-mass stars have already evolved through their more rapid life cycles and died, leaving behind cores and remnants and black holes. The ones that are still main sequence stars are the lower-mass ones, but it means there's a range of stars in various stages of evolution and with varying orbits. Lots of stars in globular clusters are in binary orbits, and occasionally stars there do collide (those are very cool objects of interest for stellar astrophysicists), but most don't -- even dense globular clusters are still mostly empty space.
DeleteIf a lot of stars did manage to coalesce in a globular cluster, though, two things would happen: first, because of interactions with other stars the giganto-star would sink pretty quickly (quick compared to the Universe, i.e. tens or hundreds of thousands of years) to the center of the cluster. Second, it would form a black hole even more quickly, because it would have enough mass to do so and because, if it were formed from stellar remnants, there wouldn't be enough light elements left to start fusion and hold up the giganto-star against its own gravity. People have looked for black holes in the centers of globular clusters, but as far as I know nobody has found definitive evidence for one.
Note: giganto-star is not an actual scientific term.
Have astronaunts ever touched a star? The two black holes coming together, when they come together will there be a explosition?
ReplyDeleteFirst answer: nope, not really. But what defines the surface of a star? A star doesn't have a crust like the Earth, so you can't step on it -- at some point an astronaut getting close enough might be interacting with the actual stellar photosphere, but even then it wouldn't be like setting foot on the Moon or Mars. It would be like putting your hand in the ocean... if the ocean were 6,000 degrees Celsius and a highly magnetized plasma. In other words, it would definitely hurt. :)
DeleteSecond answer: if there is enough material co-orbiting the black holes then there might be some interesting magnetic effects that could act like explosions, but there won't be an explosion of the black holes themselves.
Have astronaunts ever touched a star? The two black holes coming together, when they come together will there be a explosition?
ReplyDeleteHow do we know about black holes when we can't explore them, how do we know what would happen if we went into one?
ReplyDeleteWe don't know for sure, but we can make very well-informed predictions. This kind of research is in some ways in the realm of science fiction, because we can't test the hypotheses we generate based on what we know of the physics. But as I've heard the UK's Astronomer Royal (Martin Rees) say, first-rate science fiction is better than second-rate science.
DeleteWhere does all the matter go when it is sucked into the black hole? Also, is there any signs that there are humans or Aliens anywhere out in the universe? Do you think we could ever live on mars in the future?
ReplyDeleteHere's a situation where the term "black hole" sort of fails to capture what's really going on, or at least what we think is going on. It might be more accurate to think of it as a "cavern" or "chasm" than a "hole", so when things fall into a black hole they end up being compacted at the "bottom", which is analogous to the singularity at the center. At least, we think so. There are theories about objects called "white holes", in which stuff that falls into a black hole falls out of a corresponding white hole. But nothing like that has ever been observed, so it might be more useful to think of a black hole like an infinitely efficient trash compactor.
DeleteWe haven't seen any clear signs of aliens yet, but I'm keeping my fingers crossed. And I do think we could live on Mars, eventually.
What is the power of a black hole? I am wondering if their is anyway we can measure it's strength and if so what unit would it be in? Also if we could measure black holes power would all black holes have around the same power or would they be drastically different?
ReplyDeleteThere are 3 basic things we measure about a black hole:
Delete1. Its mass
2. Its rate of growth (accretion rate)
3. Its spin
The mass measures how much the black hole warps spacetime and it's analogous to the mass anything else has (it's just much more compact). The accretion rate measures how much mass is falling in, i.e. how fast the mass is changing. With many black holes this is close to 0, but when a black hole is actively accreting mass it's much easier to observe because all the matter around the black hole tends to get very luminous. The spin is harder to develop an intuitive sense for, but it measures the way the warping of spacetime is modified by the black hole having angular momentum. For a non-spinning black hole, the "surface" described by the event horizon is a sphere of a certain size. For a spinning black hole, it can be much smaller and doesn't have to have quite the same shape.
All the physics of black holes scales with the mass, by which I mean that in the computer models of black holes they just leave the mass as a variable, because you get the same answers that you just later plug the mass into to get an actual number or set of numbers for. So in some ways that means all black holes are fundamentally the same, but the masses can vary by factors of 1,000,000 or more, so actually they are also drastically different.
Good question.
Are there any theories as to where the singularity that caused the big bang came from? I know it's one of the biggest scientific mysteries, but are there any ideas besides the concept of a creator?
ReplyDeleteThe concept of the multiverse is relatively new and is pretty interesting. It says the Big Bang might not be unique, that maybe similar events are happening at random times and creating many other universes. I'm not properly an expert on the multiverse but as far as I understand it, it seems to be random fluctuations that trigger or do not trigger a Bang-like event, and similarly the fundamental parameters inside the universe (like how strong gravity is and how well atoms hold themselves together and how many atoms there are and so on) can be very different as well.
DeleteOf course, you can always ask "but what made the multiverse happen?" and so on; there's always a "but what happened before this" question. Some people argue this leaves room for a creator; others argue that a creator isn't needed (and some further argue it therefore probably doesn't exist). I think physics generally is agnostic about it; physicists are another matter!
Is there an end to the universe because if its expanding there must be and end would time stop there.
ReplyDeleteWhy would it have to end just because it's expanding? I don't know of any physics that says it can't expand forever. That's what we think it will currently do, so time won't ever stop, if that's correct.
DeleteThe Law Of Conservation of matter and energy states that they can not be created or destroyed, but transformed. When matter and energy enters a black hole, because it can't be destroyed, how is it transformed, and where does it go?
ReplyDeleteThis is a great question. A lot of energy is radiated away as something falls into a black hole, but whatever is captured by the black hole becomes part of the black hole -- black holes only grow, and whatever they eat, they keep. We think some black holes have grown in mass (i.e. energy) by factors of a million or more over their lifetimes.
DeleteIf the Laws of Conservation of Mass and Energy are true in space, then where does the mass and energy go when it's sucked up into a black hole?
ReplyDeleteI see this question was posted at the same time as Elizabeth's above and it's very similar; great minds think alike! I'll just refer you to my answer to that one. :)
DeleteWhat are the best theories on what happens to the things black holes suck up??????
ReplyDeleteFor now we think they just kind of get stuck there. If you fell into a black hole, then as you fell toward the center you'd eventually get torn apart into just atoms, and then the atoms would eventually get torn apart into particles, and so on... according to our theories at the moment it's all added to a singularity at the center, and the energy/mass of the things that fall in get added to the mass of the black hole.
DeleteCould we live on another planet where there could be other life in another galaxy?
ReplyDeleteWe'd have to find it first! We have yet to find another world that we've confirmed is habitable. Right now we're only even able to look in our own neighborhood of this galaxy; eventually we may be able to search more of our galaxy and perhaps nearby galaxies... but until we discover some completely new way of travelling through space actually going to another galaxy is not really feasible. For example, even if we could travel at the speed of light (which the laws of physics forbid for humans and spaceships and other things with mass) it would take us 2 million years to get to our nearest neighbor spiral galaxy. So if we want to send ourselves (not just robots or some kind of other self-replicating information carrier) we should probably stick to our own galaxy!
DeleteWhat is Oxford like, in the sense like the atmosphere, the mood, what the place looks like and how people act. Do they always act super serious and only study or do they also do other fun stuff in the meantime?
ReplyDeleteIn many ways Oxford is just like any other university. There are plenty of fun things to do here, and people definitely have fun! They also work very hard, both during the school terms and out of term (there's usually assigned work or reviewing to do outside the terms). Expectations are high and there is a lot of material to cover; Oxford earns its reputation as one of the finest educational institutions in the world. But it's not all studying, and actually the amount of fun the students sometimes get up to is legendary. The people are as varied as anywhere else; there are hipsters and hippies and snobs and poor people and posh people and people whose great-great-grandfathers were Masters of their Oxford college and people who've never been to university before and activists and jocks and people who just want to do the minimum amount of work to pass their degree and people who could spend years in the library or the lab. And combinations of these things and people.
DeleteIt's also true that in many ways, the Universities of Oxford and Cambridge (sometimes referred to as Oxbridge) are not like anywhere else. The College system started here and continues here in a way that's different from other places that still have it (including US universities that have residential colleges modelled after Oxbridge; places like Yale colleges are similar on the surface, but fundamentally quite different). The architecture is beautiful, varied, and authentic. Oxford has colleges ranging from 753 years old to about 20 years old. There are parks and gardens everywhere, and certainly each of the colleges has its own unique beauty.
Basically, if you watch films and TV shows like Brideshead Revisited and Endeavour and such, there's clearly a stereotype of what Oxford is, and it's not completely wrong, but nor is it completely right. If you come to Oxford as a student or researcher, you can make it what you want. I love it here.