7 ms·

> about 3 solar masses were converted into gravitational-wave energy during the coalescence This is such a staggering amount of energy to be released in such a

> about 3 solar masses were converted into gravitational-wave energy during the coalescence This is such a staggering amount of energy to be released in such a short time.

leeoniya 9y ago
more or less than https://en.wikipedia.org/wiki/Gamma-ray_burst https://en.wikipedia.org/wiki/Gamma-ray_burst ?
- throwaway613834 9y ago
  I think less? When a gamma-ray burst is pointed towards Earth, the focusing of its energy along a relatively narrow beam causes the burst to appear much brighter than it would have been were its energy emitted spherically. When this effect is taken into account, typical gamma-ray bursts are observed to have a true energy release of about 10^44 J, or about 1/2000 of a Solar mass (M) energy equivalent. [1] [1] https://en.wikipedia.org/wiki/Gamma-ray_burst#Energetics_and_beaming https://en.wikipedia.org/wiki/Gamma-ray_burst#Energetics_and...
  - rcthompson 9y ago
    I think another sentence in that article might need revision: > No known process in the universe can produce this much energy [1 solar mass equivalent] in such a short time.
- danharaj 9y ago
  The wikipedia article says that if a GRB were a spherical release of energy, they would be on the same order. However, GRB's are highly anisotropic; most of the energy is expelled in a smaller cone. One of the estimates on the page is that a typical GRB expels 1/2000th a solar mass of energy. So these gravity events are thousands of times more powerful. These scales are incomprehensible, at least to me.
- ntumlin 9y ago
  From the wiki page: > When this effect is taken into account, typical gamma-ray bursts are observed to have a true energy release of about 1044 J, or about 1/2000 of a Solar mass (M) energy equivalent So more, by about 6000 times. This is consistant with WolframAlpha's output for amount of energy: 5.361e47 J. I tried to convert this to "number of years we could power the Earth", but it just changed it from one mind boggling number into another.
  - dragonwriter 9y ago
    > > When this effect is taken into account, typical gamma-ray bursts are observed to have a true energy release of about 1044 J, Copy-paste error here from losing sup/sub formatting, that's 10^44 J, not 1044 J.
- deleted 9y ago
  [deleted]
jobu 9y ago
Didn't realize that energy could be converted into gravitational waves. It does make sense I suppose, but I always thought gravity and gravitational waves were just a side-effect of the way mass interacted with space-time.
- SomeStupidPoint 9y ago
  Can't you radiate potential gravitational energy as gravitational waves without any sort of particle changes, because potential gravitational energy is stored in the configuration of the system? If I drop my bowling ball, it has lower potential energy, but can't some of that be compensated for by the Earth-ball system radiating a gravitational wave (rather than all being converted into kinetic energy)? Similarly, don't orbiting bodies emit gravitational waves? I forget the exact dynamics, but the way that they drag just a little bit as they orbit creates waves that radiate power out of the system -- I think the Sun and Jupiter radiate something like 55 watts of gravitational waves. If you take two things that are each tens of times larger than the Sun and set them spinning an appreciable amount of the speed of light very nearby -- to the point they eventually collide -- it's not surprising they emit quite a bit more than our solar system. Think of it this way: Two large objects start orbiting slowly far apart. But because they're large and the system is big, they have a lot of orbital momentum. They pull each other close, but as they get closer, that orbital momentum has nowhere to dissipate, so they orbit faster and faster!... ...Except that because they're so massive, they slightly tug space around with them as they orbit. And because they're orbiting so fast, space doesn't have a good way to smooth itself out. So some of the momentum from the heavy things spinning far apart gets stored in wrinkles in space as they come together. Which then radiates away from there to us, ...and slightly stretches one direction of reality as it passes by. Which we detect by measuring how long two perpendicular lines are very accurately a few different places on a nearly spherical object. ...So you can model it as just the way that mass interacts with spacetime if you remember to include things like the distribution of your mass as a source of potential energy that can itself be used to generate gravitational waves. However, this does not make the whole situation any less weird to explain. Reports just tend to convert the amount of energy released through mechanisms like that in terms of mass, because it's the only thing vaguely comprehensible. (eg, 3 suns)
wlesieutre 9y ago
EDIT - Thanks to bonzini for catching a mistake, I'd typod 47 as 74 on the first line and drastically inflated everything after that. It's still huge though. Wolfram Alpha gives a solar mass as 1.988435×10^30 kg. Multiply that by (299,292,458 m/s)^2, you get ~1.78×10^47 Joules. The most powerful manmade explosion in history was Tsar Bomba, a Soviet hydrogen bomb with 210 Petajoule (210×10^15 J) yeild. Amount of energy released by the black holes merging is 8.48×10^29 times greater, so you'd need to set off that many Tsar Bombas to get equal total yeild. The universe is 4.3×10^17 seconds old, meaning if you set off a Tsar Bomba every second since the beginning of time, you'd still be off by a factor of 1.953×10^12. You need about 2,000,000,000,000,000,000 Tsar Bombas every second since the big bang to match it. The mind boggles.
- wlesieutre 9y ago
  EDIT - originally compared the last factor to number of grains of sand on Earth squared, but after catching the error above that's much too large. So how big is the remaining 2x10^12 bombs per seconds? Wikipedia has some other suggestions: ~10^12 stars in the Andromeda galaxy 1.98x10^12 links on Wikipedia 3.04×10^12 trees on Earth in 2015 3.5×10^12 estimated fish in the ocean So take every link on Wikipedia (or two thirds of the trees on Earth), turn each one into the largest hydrogen bomb ever detonated, and blow them all up every second since the beginning of the universe, and that's how much energy we're talking about. Thanks again to bonzini for spotting the rather large error!
  - rcthompson 9y ago
    Funnily enough, the past two XKCD comics are both relevant here: https://xkcd.com/1894/ https://xkcd.com/1894/ https://xkcd.com/1895/ https://xkcd.com/1895/
  - bas 9y ago
    Nicely (back of) napkinned!
    - wlesieutre 9y ago

> about 3 solar masses were converted into gravitational-wave energy during the coalescence This is such a staggering amount of energy to be released in such a short time.

leeoniya 9y ago

more or less than https://en.wikipedia.org/wiki/Gamma-ray_burst https://en.wikipedia.org/wiki/Gamma-ray_burst ?

throwaway613834 9y ago
I think less? When a gamma-ray burst is pointed towards Earth, the focusing of its energy along a relatively narrow beam causes the burst to appear much brighter than it would have been were its energy emitted spherically. When this effect is taken into account, typical gamma-ray bursts are observed to have a true energy release of about 10^44 J, or about 1/2000 of a Solar mass (M) energy equivalent. [1] [1] https://en.wikipedia.org/wiki/Gamma-ray_burst#Energetics_and_beaming https://en.wikipedia.org/wiki/Gamma-ray_burst#Energetics_and...
- rcthompson 9y ago
  I think another sentence in that article might need revision: > No known process in the universe can produce this much energy [1 solar mass equivalent] in such a short time.
danharaj 9y ago
The wikipedia article says that if a GRB were a spherical release of energy, they would be on the same order. However, GRB's are highly anisotropic; most of the energy is expelled in a smaller cone. One of the estimates on the page is that a typical GRB expels 1/2000th a solar mass of energy. So these gravity events are thousands of times more powerful. These scales are incomprehensible, at least to me.
ntumlin 9y ago
From the wiki page: > When this effect is taken into account, typical gamma-ray bursts are observed to have a true energy release of about 1044 J, or about 1/2000 of a Solar mass (M) energy equivalent So more, by about 6000 times. This is consistant with WolframAlpha's output for amount of energy: 5.361e47 J. I tried to convert this to "number of years we could power the Earth", but it just changed it from one mind boggling number into another.
- dragonwriter 9y ago
  > > When this effect is taken into account, typical gamma-ray bursts are observed to have a true energy release of about 1044 J, Copy-paste error here from losing sup/sub formatting, that's 10^44 J, not 1044 J.
deleted 9y ago
[deleted]

jobu 9y ago

Didn't realize that energy could be converted into gravitational waves. It does make sense I suppose, but I always thought gravity and gravitational waves were just a side-effect of the way mass interacted with space-time.

SomeStupidPoint 9y ago
Can't you radiate potential gravitational energy as gravitational waves without any sort of particle changes, because potential gravitational energy is stored in the configuration of the system? If I drop my bowling ball, it has lower potential energy, but can't some of that be compensated for by the Earth-ball system radiating a gravitational wave (rather than all being converted into kinetic energy)? Similarly, don't orbiting bodies emit gravitational waves? I forget the exact dynamics, but the way that they drag just a little bit as they orbit creates waves that radiate power out of the system -- I think the Sun and Jupiter radiate something like 55 watts of gravitational waves. If you take two things that are each tens of times larger than the Sun and set them spinning an appreciable amount of the speed of light very nearby -- to the point they eventually collide -- it's not surprising they emit quite a bit more than our solar system. Think of it this way: Two large objects start orbiting slowly far apart. But because they're large and the system is big, they have a lot of orbital momentum. They pull each other close, but as they get closer, that orbital momentum has nowhere to dissipate, so they orbit faster and faster!... ...Except that because they're so massive, they slightly tug space around with them as they orbit. And because they're orbiting so fast, space doesn't have a good way to smooth itself out. So some of the momentum from the heavy things spinning far apart gets stored in wrinkles in space as they come together. Which then radiates away from there to us, ...and slightly stretches one direction of reality as it passes by. Which we detect by measuring how long two perpendicular lines are very accurately a few different places on a nearly spherical object. ...So you can model it as just the way that mass interacts with spacetime if you remember to include things like the distribution of your mass as a source of potential energy that can itself be used to generate gravitational waves. However, this does not make the whole situation any less weird to explain. Reports just tend to convert the amount of energy released through mechanisms like that in terms of mass, because it's the only thing vaguely comprehensible. (eg, 3 suns)

wlesieutre 9y ago

EDIT - Thanks to bonzini for catching a mistake, I'd typod 47 as 74 on the first line and drastically inflated everything after that. It's still huge though. Wolfram Alpha gives a solar mass as 1.988435×10^30 kg. Multiply that by (299,292,458 m/s)^2, you get ~1.78×10^47 Joules. The most powerful manmade explosion in history was Tsar Bomba, a Soviet hydrogen bomb with 210 Petajoule (210×10^15 J) yeild. Amount of energy released by the black holes merging is 8.48×10^29 times greater, so you'd need to set off that many Tsar Bombas to get equal total yeild. The universe is 4.3×10^17 seconds old, meaning if you set off a Tsar Bomba every second since the beginning of time, you'd still be off by a factor of 1.953×10^12. You need about 2,000,000,000,000,000,000 Tsar Bombas every second since the big bang to match it. The mind boggles.

wlesieutre 9y ago
EDIT - originally compared the last factor to number of grains of sand on Earth squared, but after catching the error above that's much too large. So how big is the remaining 2x10^12 bombs per seconds? Wikipedia has some other suggestions: ~10^12 stars in the Andromeda galaxy 1.98x10^12 links on Wikipedia 3.04×10^12 trees on Earth in 2015 3.5×10^12 estimated fish in the ocean So take every link on Wikipedia (or two thirds of the trees on Earth), turn each one into the largest hydrogen bomb ever detonated, and blow them all up every second since the beginning of the universe, and that's how much energy we're talking about. Thanks again to bonzini for spotting the rather large error!
- rcthompson 9y ago
  Funnily enough, the past two XKCD comics are both relevant here: https://xkcd.com/1894/ https://xkcd.com/1894/ https://xkcd.com/1895/ https://xkcd.com/1895/
- bas 9y ago
  Nicely (back of) napkinned!
  - wlesieutre 9y ago