WHAT IS A GRAVITATIONAL WAVE?
\n\"A gravitational wave is an invisible (yet incredibly fast) ripple in space. Gravitational waves travel at the speed of light (186,000 miles per second). These waves squeeze and stretch anything in their path as they pass by.\"
\nWHAT CAUSES GRAVITATIONAL WAVES?
\n\"The most powerful gravitational waves are created when objects move at very high speeds. Some examples of events that could cause a gravitational wave are:\"
\n\"When a star explodes asymmetrically (called a supernova).\"
\n\"When two big stars orbit each other.\"
\n\"When two black holes orbit each other and merge\"
\nHOW DO WE KNOW THAT GRAVITATIONAL WAVES EXIST? LIGO
\n\"In 2015, scientists detected gravitational waves for the very first time. They used a very sensitive instrument called LIGO (Laser Interferometer Gravitational-Wave Observatory). These first gravitational waves happened when two black holes crashed into one another. The collision happened 1.3 billion years ago. But, the ripples didn’t make it to Earth until 2015!\"
\nhttps://spaceplace.nasa.gov/gravitational-waves/en/
\nHOW ARE GRAVITATIONAL WAVES DETECTED?
\n\"When a gravitational wave passes by Earth, it squeezes and stretches space. LIGO can detect this squeezing and stretching. Each LIGO observatory has two “arms” that are each more than 2 miles (4 kilometers) long. A passing gravitational wave causes the length of the arms to change slightly. The observatory uses lasers, mirrors, and extremely sensitive instruments to detect these tiny changes.\"
\nhttps://spaceplace.nasa.gov/gravitational-waves/en/
\nGRAVITATIONAL-WAVE DETECTION AND BLACK HOLES
\n\"The first direct gravitational-wave detection was made by the Advanced Laser Interferometer Gravitational Wave Observatory on September 14, 2015.\"
\"The GW150914 signal was strong enough to be apparent, without using any waveform model, in the filtered detector strain data. Here those features of the signal visible in these data are used, along with only such concepts from Newtonian and General Relativity as are accessible to anyone with a general physics background.\"
\n\"The signal was produced by the inspiral and subsequent merger of two black holes. The black holes were each of approximately 35 Msun, still orbited each other as close as 350 km apart and subsequently merged to form a single black hole. Similar reasoning, directly from the data, is used to roughly estimate how far these black holes were from the Earth, and the energy that they radiated in gravitational waves.\"
\nLSC and Virgo Collaborations, Annalen der Physik, 2016
\n\nHOW DO WE KNOW THE SIGNAL WAS FROM A COMPACT BINARY ?
\n\"The compact binaries that have been observed in our galaxy are in the galactic disc, namely in high ISM density. Merger rate estimates based on these binaries (Kalogera et al. 2004a,b) suggest a comparable rate of events to the beaming corrected rate inferred from short GRBs. This implies that, while there may (or may not) be a merger population at low-density environment, there must be (regardless of the whether there is a connection to short GRBs) a large population of the mergers that take place in Milky Way ISM-like density. \"
\nhttps://academic.oup.com/mnras/article/430/3/2121/981341
\nHOW DO WE KNOW BINARY OBJECTS WERE BLACK HOLES? (OR SOMETHING THAT BEHAVES LIKE THEM)
\n\"Black holes can be detected by their gravitational effect on luminous matter. If a black hole exists in a close binary system, it can be detected indirectly. Gas ripped from the companion star will spiral in toward the black hole. As it does so, it is heated up (by tidal heating, and by friction as it rubs against neighboring gas). The hot gas emits X-rays as it undergoes its death spiral to the event horizon. (Once it's inside the event horizon, we don't see the gas any more, but it's highly visible as long as it's outside.) If you are hunting for black holes, it's good to start by looking for binary star systems which are also strong X-ray sources.\"
\nhttp://www.astronomy.ohio-state.edu/~ryden/ast162_6/notes26.html
\"THE ECCENTRICITY ENHANCEMENT EFFECT OF (IMRI) INTERMEDIATE-MASS-RATIO-INSPIRALS: DARK MATTER AND BLACK HOLE MASS
\nAuthors: Meirong Tang, Jiancheng Wang - DOI:10.1088/1674-1137/abc680 arXiv:2005.11933 [gr-qc]
\"It was found that the dark matter (DM) in the intermediate-mass-ratio-inspiral (IMRI) system has a significant enhancement effect on the orbital eccentricity of the stellar massive compact object, such as a black hole (BH), which may be tested by space-based gravitational wave (GW) detectors including LISA, Taiji and Tianqin in future observations.\"
\n\"In that paper, the authors studied the enhancement effect of the eccentricity for an IMRI under different DM (dark matter) density profiles and center BH masses. Their results are as follows: (1) in terms of the general DM spike distribution, the enhancement of the eccentricity is basically consistent with the power-law profile, which indicates that it is reasonable to adopt the power-law profile; (2) in the presence of DM (dark matter) spike, the different masses of the center BH will affect the eccentricity, which provides a new way for us to detect the BH's mass; (3) considering the change of the eccentricity in the presence and absence of DM spike, they founnd that it is possible to distinguish DM models by measuring the eccentricity at the scale of about 105GM/c2.\"
\nhttps://arxiv.org/abs/2005.11933
\nARGUMENT FOR A COMPACT BINARY
\n\"GW signal shows several oscillations of massive body/bodies increasing in frequency & amplitude\"
\n\"Not a perturbed system returning to equilibrium (damped sinusoid).\"
\n\"Only physically plausible configuration is rotating (orbiting) binary.\"
\n\"Binary masses and orbital radius imply compact objects, i.e. radius comparable to Schwarzschild\"
\n\nARE BLACK HOLES BLACK?
\n\"There’s this kind of irony of black holes that are black and invisible. But they’re also some of the brightest objects in the entire known universe. And the reason is, because when you tend to get too close to a black hole, if you’re a planet or a star cloud of gas, you get whipped around into a really fast orbit going nearly the speed of light, heated up to millions of degrees and shining out in bright ultraviolet, X-ray, radio, just really bright, bright sources of light coming from not the black hole itself, but from the effect that it has on anyone who gets too close to it. So that’s why, that’s how we see them. That’s how we study them. For the most part.\"
\n\"One in 1,000 stars becomes a black hole at the end of its life. And if you think about the fact that we have over 100 billion stars in the Milky Way, you do the math and you end up with over 100 million black holes floating around the Milky Way. And we’ve seen 40 of them. So that leaves 99,999,000 and change that we’ve never even detected, and they’re just going to be sprinkled throughout the, the Milky Way, just like all the stars. And again, do a little bit of math, and the chances are, that there’s a black hole that we’ve never even seen within only, say, 25 light-years of the Earth. I mean, it doesn’t pose any immediate risk. But, when whenever it happened, billion years ago, when it went supernova, it would have been a pretty bright day out.\"
\nhttps://scitechdaily.com/nasas-gravity-assist-black-hole-mysteries/
\nRARE AND RECORD-BREAKING BLACK HOLES
\n\"While even the most “normal” black hole seems exotic compared to the tranquil objects in our solar system, there are some record-breaking oddballs. Tag along as we look at the biggest, closest, farthest, and even “spinniest” black holes discovered in the universe … that we know of right now!\"
\n\"Located 700 million light-years away in the galaxy Holmberg 15A, astronomers found a black hole that is a whopping 40 billion times the mass of the Sun — setting the record for the biggest black hole found so far. On the other hand, the smallest known black hole isn’t quite so easy to pinpoint. There are several black holes with masses around five times that of our Sun. There’s even one candidate with just two and a half times the Sun’s mass, but scientists aren’t sure whether it’s the smallest known black hole or actually the heaviest known neutron star!\"
\n\"You may need to take a seat for this one. The black hole GRS 1915+105 will make you dizzier than an afternoon at an amusement park, as it spins over 1,000 times per second! Maybe even more bizarre than how fast this black hole is spinning is what it means for a black hole to spin at all! What we’re actually measuring is how strongly the black hole drags the space-time right outside its event horizon — the point where nothing can escape.\"
\n\"If you’re from Earth, the closest black hole that we know of right now, Mon X-1 in the constellation Monoceros, is about 3,000 light-years away. But never fear — that’s still really far away! The farthest known black hole is J0313-1806. The light from its surroundings took a whopping 13 billion years to get to us! And with the universe constantly expanding, that distance continues to grow.\"
\n\"Three scientists received the 2017 Nobel Prize in Physics for using LIGO to observe gravitational waves that were sent out from colliding stellar-mass black holes. Though gravitational waves are hard to detect, they offer a way to find black holes without having to see any light.\"
\nhttps://nasa.tumblr.com/post/648639029765668864/rare-record-breaking-black-holes
", "messages": [ { "id": "1371357", "postDate": "06/30/2021 23:11:49", "content": "WHAT IS A GRAVITATIONAL WAVE?
\n\"A gravitational wave is an invisible (yet incredibly fast) ripple in space. Gravitational waves travel at the speed of light (186,000 miles per second). These waves squeeze and stretch anything in their path as they pass by.\"
\nWHAT CAUSES GRAVITATIONAL WAVES?
\n\"The most powerful gravitational waves are created when objects move at very high speeds. Some examples of events that could cause a gravitational wave are:\"
\n\"When a star explodes asymmetrically (called a supernova).\"
\n\"When two big stars orbit each other.\"
\n\"When two black holes orbit each other and merge\"
\nHOW DO WE KNOW THAT GRAVITATIONAL WAVES EXIST? LIGO
\n\"In 2015, scientists detected gravitational waves for the very first time. They used a very sensitive instrument called LIGO (Laser Interferometer Gravitational-Wave Observatory). These first gravitational waves happened when two black holes crashed into one another. The collision happened 1.3 billion years ago. But, the ripples didn’t make it to Earth until 2015!\"
\nhttps://spaceplace.nasa.gov/gravitational-waves/en/
\nHOW ARE GRAVITATIONAL WAVES DETECTED?
\n\"When a gravitational wave passes by Earth, it squeezes and stretches space. LIGO can detect this squeezing and stretching. Each LIGO observatory has two “arms” that are each more than 2 miles (4 kilometers) long. A passing gravitational wave causes the length of the arms to change slightly. The observatory uses lasers, mirrors, and extremely sensitive instruments to detect these tiny changes.\"
\nhttps://spaceplace.nasa.gov/gravitational-waves/en/
\nGRAVITATIONAL-WAVE DETECTION AND BLACK HOLES
\n\"The first direct gravitational-wave detection was made by the Advanced Laser Interferometer Gravitational Wave Observatory on September 14, 2015.\"
\"The GW150914 signal was strong enough to be apparent, without using any waveform model, in the filtered detector strain data. Here those features of the signal visible in these data are used, along with only such concepts from Newtonian and General Relativity as are accessible to anyone with a general physics background.\"
\n\"The signal was produced by the inspiral and subsequent merger of two black holes. The black holes were each of approximately 35 Msun, still orbited each other as close as 350 km apart and subsequently merged to form a single black hole. Similar reasoning, directly from the data, is used to roughly estimate how far these black holes were from the Earth, and the energy that they radiated in gravitational waves.\"
\nLSC and Virgo Collaborations, Annalen der Physik, 2016
\n\nHOW DO WE KNOW THE SIGNAL WAS FROM A COMPACT BINARY ?
\n\"The compact binaries that have been observed in our galaxy are in the galactic disc, namely in high ISM density. Merger rate estimates based on these binaries (Kalogera et al. 2004a,b) suggest a comparable rate of events to the beaming corrected rate inferred from short GRBs. This implies that, while there may (or may not) be a merger population at low-density environment, there must be (regardless of the whether there is a connection to short GRBs) a large population of the mergers that take place in Milky Way ISM-like density. \"
\nhttps://academic.oup.com/mnras/article/430/3/2121/981341
\nHOW DO WE KNOW BINARY OBJECTS WERE BLACK HOLES? (OR SOMETHING THAT BEHAVES LIKE THEM)
\n\"Black holes can be detected by their gravitational effect on luminous matter. If a black hole exists in a close binary system, it can be detected indirectly. Gas ripped from the companion star will spiral in toward the black hole. As it does so, it is heated up (by tidal heating, and by friction as it rubs against neighboring gas). The hot gas emits X-rays as it undergoes its death spiral to the event horizon. (Once it's inside the event horizon, we don't see the gas any more, but it's highly visible as long as it's outside.) If you are hunting for black holes, it's good to start by looking for binary star systems which are also strong X-ray sources.\"
\nhttp://www.astronomy.ohio-state.edu/~ryden/ast162_6/notes26.html
\"THE ECCENTRICITY ENHANCEMENT EFFECT OF (IMRI) INTERMEDIATE-MASS-RATIO-INSPIRALS: DARK MATTER AND BLACK HOLE MASS
\nAuthors: Meirong Tang, Jiancheng Wang - DOI:10.1088/1674-1137/abc680 arXiv:2005.11933 [gr-qc]
\"It was found that the dark matter (DM) in the intermediate-mass-ratio-inspiral (IMRI) system has a significant enhancement effect on the orbital eccentricity of the stellar massive compact object, such as a black hole (BH), which may be tested by space-based gravitational wave (GW) detectors including LISA, Taiji and Tianqin in future observations.\"
\n\"In that paper, the authors studied the enhancement effect of the eccentricity for an IMRI under different DM (dark matter) density profiles and center BH masses. Their results are as follows: (1) in terms of the general DM spike distribution, the enhancement of the eccentricity is basically consistent with the power-law profile, which indicates that it is reasonable to adopt the power-law profile; (2) in the presence of DM (dark matter) spike, the different masses of the center BH will affect the eccentricity, which provides a new way for us to detect the BH's mass; (3) considering the change of the eccentricity in the presence and absence of DM spike, they founnd that it is possible to distinguish DM models by measuring the eccentricity at the scale of about 105GM/c2.\"
\nhttps://arxiv.org/abs/2005.11933
\nARGUMENT FOR A COMPACT BINARY
\n\"GW signal shows several oscillations of massive body/bodies increasing in frequency & amplitude\"
\n\"Not a perturbed system returning to equilibrium (damped sinusoid).\"
\n\"Only physically plausible configuration is rotating (orbiting) binary.\"
\n\"Binary masses and orbital radius imply compact objects, i.e. radius comparable to Schwarzschild\"
\n\nARE BLACK HOLES BLACK?
\n\"There’s this kind of irony of black holes that are black and invisible. But they’re also some of the brightest objects in the entire known universe. And the reason is, because when you tend to get too close to a black hole, if you’re a planet or a star cloud of gas, you get whipped around into a really fast orbit going nearly the speed of light, heated up to millions of degrees and shining out in bright ultraviolet, X-ray, radio, just really bright, bright sources of light coming from not the black hole itself, but from the effect that it has on anyone who gets too close to it. So that’s why, that’s how we see them. That’s how we study them. For the most part.\"
\n\"One in 1,000 stars becomes a black hole at the end of its life. And if you think about the fact that we have over 100 billion stars in the Milky Way, you do the math and you end up with over 100 million black holes floating around the Milky Way. And we’ve seen 40 of them. So that leaves 99,999,000 and change that we’ve never even detected, and they’re just going to be sprinkled throughout the, the Milky Way, just like all the stars. And again, do a little bit of math, and the chances are, that there’s a black hole that we’ve never even seen within only, say, 25 light-years of the Earth. I mean, it doesn’t pose any immediate risk. But, when whenever it happened, billion years ago, when it went supernova, it would have been a pretty bright day out.\"
\nhttps://scitechdaily.com/nasas-gravity-assist-black-hole-mysteries/
\nRARE AND RECORD-BREAKING BLACK HOLES
\n\"While even the most “normal” black hole seems exotic compared to the tranquil objects in our solar system, there are some record-breaking oddballs. Tag along as we look at the biggest, closest, farthest, and even “spinniest” black holes discovered in the universe … that we know of right now!\"
\n\"Located 700 million light-years away in the galaxy Holmberg 15A, astronomers found a black hole that is a whopping 40 billion times the mass of the Sun — setting the record for the biggest black hole found so far. On the other hand, the smallest known black hole isn’t quite so easy to pinpoint. There are several black holes with masses around five times that of our Sun. There’s even one candidate with just two and a half times the Sun’s mass, but scientists aren’t sure whether it’s the smallest known black hole or actually the heaviest known neutron star!\"
\n\"You may need to take a seat for this one. The black hole GRS 1915+105 will make you dizzier than an afternoon at an amusement park, as it spins over 1,000 times per second! Maybe even more bizarre than how fast this black hole is spinning is what it means for a black hole to spin at all! What we’re actually measuring is how strongly the black hole drags the space-time right outside its event horizon — the point where nothing can escape.\"
\n\"If you’re from Earth, the closest black hole that we know of right now, Mon X-1 in the constellation Monoceros, is about 3,000 light-years away. But never fear — that’s still really far away! The farthest known black hole is J0313-1806. The light from its surroundings took a whopping 13 billion years to get to us! And with the universe constantly expanding, that distance continues to grow.\"
\n\"Three scientists received the 2017 Nobel Prize in Physics for using LIGO to observe gravitational waves that were sent out from colliding stellar-mass black holes. Though gravitational waves are hard to detect, they offer a way to find black holes without having to see any light.\"
\nhttps://nasa.tumblr.com/post/648639029765668864/rare-record-breaking-black-holes
", "rawMarkdown": "WHAT IS A GRAVITATIONAL WAVE?\n\n\"A gravitational wave is an invisible (yet incredibly fast) ripple in space. Gravitational waves travel at the speed of light (186,000 miles per second). These waves squeeze and stretch anything in their path as they pass by.\"\n\nWHAT CAUSES GRAVITATIONAL WAVES?\n\n\"The most powerful gravitational waves are created when objects move at very high speeds. Some examples of events that could cause a gravitational wave are:\"\n\n\"When a star explodes asymmetrically (called a supernova).\"\n\n\"When two big stars orbit each other.\"\n\n\"When two black holes orbit each other and merge\"\n\nHOW DO WE KNOW THAT GRAVITATIONAL WAVES EXIST? LIGO\n\n\"In 2015, scientists detected gravitational waves for the very first time. They used a very sensitive instrument called LIGO (Laser Interferometer Gravitational-Wave Observatory). These first gravitational waves happened when two black holes crashed into one another. The collision happened 1.3 billion years ago. But, the ripples didn’t make it to Earth until 2015!\"\n\nhttps://spaceplace.nasa.gov/gravitational-waves/en/\n\nHOW ARE GRAVITATIONAL WAVES DETECTED?\n\n\"When a gravitational wave passes by Earth, it squeezes and stretches space. LIGO can detect this squeezing and stretching. Each LIGO observatory has two “arms” that are each more than 2 miles (4 kilometers) long. A passing gravitational wave causes the length of the arms to change slightly. The observatory uses lasers, mirrors, and extremely sensitive instruments to detect these tiny changes.\"\n\nhttps://spaceplace.nasa.gov/gravitational-waves/en/\n\nGRAVITATIONAL-WAVE DETECTION AND BLACK HOLES\n\"The first direct gravitational-wave detection was made by the Advanced Laser Interferometer Gravitational Wave Observatory on September 14, 2015.\"\n\n\"The GW150914 signal was strong enough to be apparent, without using any waveform model, in the filtered detector strain data. Here those features of the signal visible in these data are used, along with only such concepts from Newtonian and General Relativity as are accessible to anyone with a general physics background.\"\n\n\"The signal was produced by the inspiral and subsequent merger of two black holes. The black holes were each of approximately 35 Msun, still orbited each other as close as 350 km apart and subsequently merged to form a single black hole. Similar reasoning, directly from the data, is used to roughly estimate how far these black holes were from the Earth, and the energy that they radiated in gravitational waves.\"\n\nLSC and Virgo Collaborations, Annalen der Physik, 2016\n\nhttps://indico.cern.ch/event/779256/contributions/3242644/attachments/1780516/2896456/dent_ggww_2.pdf\n\nHOW DO WE KNOW THE SIGNAL WAS FROM A COMPACT BINARY ?\n\n\"The compact binaries that have been observed in our galaxy are in the galactic disc, namely in high ISM density. Merger rate estimates based on these binaries (Kalogera et al. 2004a,b) suggest a comparable rate of events to the beaming corrected rate inferred from short GRBs. This implies that, while there may (or may not) be a merger population at low-density environment, there must be (regardless of the whether there is a connection to short GRBs) a large population of the mergers that take place in Milky Way ISM-like density. \"\n\nhttps://academic.oup.com/mnras/article/430/3/2121/981341\n\nHOW DO WE KNOW BINARY OBJECTS WERE BLACK HOLES? (OR SOMETHING THAT BEHAVES LIKE THEM)\n\n\"Black holes can be detected by their gravitational effect on luminous matter. If a black hole exists in a close binary system, it can be detected indirectly. Gas ripped from the companion star will spiral in toward the black hole. As it does so, it is heated up (by tidal heating, and by friction as it rubs against neighboring gas). The hot gas emits X-rays as it undergoes its death spiral to the event horizon. (Once it's inside the event horizon, we don't see the gas any more, but it's highly visible as long as it's outside.) If you are hunting for black holes, it's good to start by looking for binary star systems which are also strong X-ray sources.\"\nhttp://www.astronomy.ohio-state.edu/~ryden/ast162_6/notes26.html\n\n\"THE ECCENTRICITY ENHANCEMENT EFFECT OF (IMRI) INTERMEDIATE-MASS-RATIO-INSPIRALS: DARK MATTER AND BLACK HOLE MASS\nAuthors: Meirong Tang, Jiancheng Wang - DOI:10.1088/1674-1137/abc680 arXiv:2005.11933 [gr-qc]\n\n\"It was found that the dark matter (DM) in the intermediate-mass-ratio-inspiral (IMRI) system has a significant enhancement effect on the orbital eccentricity of the stellar massive compact object, such as a black hole (BH), which may be tested by space-based gravitational wave (GW) detectors including LISA, Taiji and Tianqin in future observations.\"\n\n\"In that paper, the authors studied the enhancement effect of the eccentricity for an IMRI under different DM (dark matter) density profiles and center BH masses. Their results are as follows: (1) in terms of the general DM spike distribution, the enhancement of the eccentricity is basically consistent with the power-law profile, which indicates that it is reasonable to adopt the power-law profile; (2) in the presence of DM (dark matter) spike, the different masses of the center BH will affect the eccentricity, which provides a new way for us to detect the BH's mass; (3) considering the change of the eccentricity in the presence and absence of DM spike, they founnd that it is possible to distinguish DM models by measuring the eccentricity at the scale of about 105GM/c2.\"\n\nhttps://arxiv.org/abs/2005.11933\n\nARGUMENT FOR A COMPACT BINARY \n\n\"GW signal shows several oscillations of massive body/bodies increasing in frequency & amplitude\"\n\n\"Not a perturbed system returning to equilibrium (damped sinusoid).\"\n\n\"Only physically plausible configuration is rotating (orbiting) binary.\"\n\n\"Binary masses and orbital radius imply compact objects, i.e. radius comparable to Schwarzschild\"\n\nhttps://indico.cern.ch/event/779256/contributions/3242644/attachments/1780516/2896456/dent_ggww_2.pdf\n\nARE BLACK HOLES BLACK?\n\n\"There’s this kind of irony of black holes that are black and invisible. But they’re also some of the brightest objects in the entire known universe. And the reason is, because when you tend to get too close to a black hole, if you’re a planet or a star cloud of gas, you get whipped around into a really fast orbit going nearly the speed of light, heated up to millions of degrees and shining out in bright ultraviolet, X-ray, radio, just really bright, bright sources of light coming from not the black hole itself, but from the effect that it has on anyone who gets too close to it. So that’s why, that’s how we see them. That’s how we study them. For the most part.\"\n\n\"One in 1,000 stars becomes a black hole at the end of its life. And if you think about the fact that we have over 100 billion stars in the Milky Way, you do the math and you end up with over 100 million black holes floating around the Milky Way. And we’ve seen 40 of them. So that leaves 99,999,000 and change that we’ve never even detected, and they’re just going to be sprinkled throughout the, the Milky Way, just like all the stars. And again, do a little bit of math, and the chances are, that there’s a black hole that we’ve never even seen within only, say, 25 light-years of the Earth. I mean, it doesn’t pose any immediate risk. But, when whenever it happened, billion years ago, when it went supernova, it would have been a pretty bright day out.\"\n\nhttps://scitechdaily.com/nasas-gravity-assist-black-hole-mysteries/\n\n\nRARE AND RECORD-BREAKING BLACK HOLES\n\n\"While even the most “normal” black hole seems exotic compared to the tranquil objects in our solar system, there are some record-breaking oddballs. Tag along as we look at the biggest, closest, farthest, and even “spinniest” black holes discovered in the universe … that we know of right now!\"\n\n\"Located 700 million light-years away in the galaxy Holmberg 15A, astronomers found a black hole that is a whopping 40 billion times the mass of the Sun — setting the record for the biggest black hole found so far. On the other hand, the smallest known black hole isn’t quite so easy to pinpoint. There are several black holes with masses around five times that of our Sun. There’s even one candidate with just two and a half times the Sun’s mass, but scientists aren’t sure whether it’s the smallest known black hole or actually the heaviest known neutron star!\"\n\n\"You may need to take a seat for this one. The black hole GRS 1915+105 will make you dizzier than an afternoon at an amusement park, as it spins over 1,000 times per second! Maybe even more bizarre than how fast this black hole is spinning is what it means for a black hole to spin at all! What we’re actually measuring is how strongly the black hole drags the space-time right outside its event horizon — the point where nothing can escape.\"\n\n\"If you’re from Earth, the closest black hole that we know of right now, Mon X-1 in the constellation Monoceros, is about 3,000 light-years away. But never fear — that’s still really far away! The farthest known black hole is J0313-1806. The light from its surroundings took a whopping 13 billion years to get to us! And with the universe constantly expanding, that distance continues to grow.\"\n\n\"Three scientists received the 2017 Nobel Prize in Physics for using LIGO to observe gravitational waves that were sent out from colliding stellar-mass black holes. Though gravitational waves are hard to detect, they offer a way to find black holes without having to see any light.\"\n\nhttps://nasa.tumblr.com/post/648639029765668864/rare-record-breaking-black-holes", "votes": null }, { "id": "1374362", "postDate": "07/03/2021 08:34:20", "content": "@mpwolke, Thank you for the information, it is really very informative and easy to understand!
", "rawMarkdown": "mpwolke, Thank you for the information, it is really very informative and easy to understand!", "votes": null }, { "id": "1375067", "postDate": "07/03/2021 20:18:46", "content": "Thank you Alexei. I don't know how people can analyse data without knowing data. Besides, that subject is very complex to be explained in one topic. That's why I wrote in the title \"a little bit\". Just like pils, small portions that users should go deeper (with the sources) if they want to understand the data they are going to face.
\nHow to make any ML model if you never learned about your data before? I've got no clue.
Hey,
\nThank you all for taking part in our competition. The participation has been overwhelmingly positive. We are currently conducting a survey to gauge the demographic and outreach achieved. Kindly spare 2min and fill in this survey https://forms.gle/QP9L16niPexozyhu5.
\nThank you all,
\nRegards,
\nChris
@mpwolke, Thank you for the information, it is really very informative and easy to understand!
", "votes": null, "replies": [ { "id": 1375067, "author_name": "mpwolke", "author_url": "", "post_date": "07/03/2021 20:18:46", "content": "Thank you Alexei. I don't know how people can analyse data without knowing data. Besides, that subject is very complex to be explained in one topic. That's why I wrote in the title \"a little bit\". Just like pils, small portions that users should go deeper (with the sources) if they want to understand the data they are going to face.
\nHow to make any ML model if you never learned about your data before? I've got no clue.
Hey,
\nThank you all for taking part in our competition. The participation has been overwhelmingly positive. We are currently conducting a survey to gauge the demographic and outreach achieved. Kindly spare 2min and fill in this survey https://forms.gle/QP9L16niPexozyhu5.
\nThank you all,
\nRegards,
\nChris