October 24, 2015 at 08:07The final question is what are we? where are we going and all that
Questions such as: “Who are we?” And “Where are we going?” Have interested philosophers of all time, but in such formulations, and with the help of philosophy, it is hardly possible to get an answer to them better than “42”. But astronomy has already managed to answer the questions “what are we?” And “where are we going?” Literally.
The history of the substance of which we are composed
During the big bang, only the lightest elements were formed: 75% - hydrogen, about 25% helium, about 0.01% deuterium and helium-3, 10 -10 lithium, and insignificant fractions of other substances.
Where could everything else come from that surrounds us?
Earth's chemical composition (incomplete)
Answer by astrophysicist Neil DeGrasse Tyson:
There were several pathways for the formation of substances, but most are associated with the bowels of ancient stars:
So everything that surrounds us - from ourselves, to leaves on trees, from the air we breathe to minerals in the bowels of the Earth - was once part of the ancient stars that died in supernova explosions have given us life. Our Sun belongs to the third generation of stars.
Our movement in space.
Many are aware that even when sitting still, we move with the Earth, many will be able to name 2 or 3 of these components of the movement, but in fact there are 6 of them:
1) The rotation of the Earth around its axis. Period - 1 stellar day (23 h 56 min 4.1 sec).
This speed depends on the latitude of the area where you are located, and varies from 1674 km / h for the equator to zero for geographical poles (magnetic poles are slightly different from them). However, even while at the pole, you will rotate:
Long exposure photography, La Silla Observatory
Such a “slow” by our standards rotation speed for such a planet as the Earth is quite noticeable - the deviation from sphericity is 21.3 km. Together with the rotation itself, this creates an interesting effect - the acceleration of gravity g at the poles is 9.832 m / s², and at the equator - 9.78 m / s² (with the standard value used for calculations 9.800665 m / s²), so at the equator you will weigh 0.5% less than at the pole. These seemingly insignificant differences are of great importance for missiles - the Soyuz launch vehicle from the Kourou spaceport (5 ° north latitude) can output 25-30% more payload than from the Baikonur cosmodrome (45 ° north), but there are Cosmodromes, which are located further north.
The length of the day gradually increases at a speed of 1 second in 50 thousand years. Therefore, they refused to be bound to the Earth days in the measurement of time back in 1967 - now the second is defined as the time interval for which the cesium-133 atom passes between two ultrathin levels of the ground state 9,192,631,770 times. By the way, the meter has also not been tied to the standards since 1983 - now it is defined as 1/299 792 458 of the distance that light travels in one second. Perhaps by the 2018 meeting of the International Committee of Weights and Measures we will be able to abandon the last anachronism - the weight standard (they want to express it from Planck's constant equal to 6.62606x, where the x value will be determined by the CODATA committee).
2) The next component is the rotation of the Earth around the Sun. Period - 1 sidereal year (365.2564 days)
The earth moves at a speed of 29.78 km / s, this speed increases slightly from July 3 to January 3, and then decreases to its previous level. The orbit of the Earth is very close to circular, due to which the Earth has very small (by cosmic standards) temperature differences.
To determine where we are currently moving, it is necessary to postpone 90 ° to the right from the current position of the Sun (for residents of the southern hemisphere, it will have to be postponed to the left).
The movement of the sun in the constellations:
3) The movement of the solar system relative to stellar neighbors. The period is 66 million years.
This component is 19.4 km / s, and is directed (at the moment) in the direction of the Hercules constellation, on the border with the constellation Lyra, the direction is α = 270 °, β = + 30 ° (hereinafter, the direction is set relative to the galaxy). This component is interesting in that it is directed perpendicular to the plane of the Milky Way, and the Sun either rises above the galactic disk, then falls below it, crossing it every 33 million years.
4) The movement of the Sun around the center of the galaxy. The period is 225-250 million years.
The sun rotates around the center of the Milky Way at an enormous speed of about 220 km / s, but due to its even gigantic radius of 27,200 light years, this is a very slow process. For comparison, primates appeared only 80 million years ago, and during this time only a third of the “galactic year” passed. Our entire history, from the first cave paintings 40 thousand years ago, to the release of a man into space, passed in 0.06 degrees (3.5 arc minutes) of this revolution.
5) The movement of a local group of galaxies.
We are moving relative to the local group at a speed of ≈ 115 km / s, in the direction α ≈ 87 °, β ≈ 69 °. The period of revolution here is already difficult to determine - for this it is necessary to calculate the center of mass of our galaxies, which is incredibly difficult. And then calculate the movements of all galaxies relative to each other - which also does not differ in simplicity ...
6) The last and most fundamental movement remains - the movement of our galaxy relative to space itself, how can we measure it? The theory of relativity postulated that we will not be able to determine the speed of our movement, being in an inertial reference frame.
And there was no way to solve this problem until 1969, when the dipole component was not detected in the relict radiation: The
relict radiation should have been anisotropic in all directions, but in the direction of the Hydra constellation this radiation was “warmer”, and in the opposite direction "Colder." This was the answer to this question, we were able to measure the last component of our movement!
During this time, a long way was taken in the study of CMB, for its study, NASA sequentially sent two space telescopes:
And after that, its telescope Planck sent ESA:
Data from these telescopes allowed us to estimate the speed and direction of movement of the local cluster as 627 ± 22 km / s in the direction l = 276 ± 3 ° longitude, and b = 30 ± 3 ° longitude. It also made it possible to measure the components of dark energy, dark matter and ordinary matter with an accuracy of tenths of a%. It allowed to find out the time of the birth of the Universe - 13.799 billion years with an accuracy of ± 210 million years. Relict pattern of the Planck space observatory of the European Space Agency (clickable)
Astrophysicists based on the data on the motion of the 800 nearest galaxies to us have already estimated the direction and speed of our Milky Way relative to the large-scale structure of the Universe. These data allow us to judge the motion of most galaxies, including ours, towards the Great Attractor - a gravitational anomaly, the composition of which is still poorly understood.
Links:
www.astronet.ru/db/msg/1189375 Sun Movement (astronet.ru)
nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html Sun Information (NASA)
Dipole Anisotropy in the COBE DMR First-Year Sky Maps. The astrophysical journal
About number 42, for those who do not know
About the number 42, for those who do not know
- Forty-two! Squealed Lunkkuool. “And that's all you can say after seven and a half million years of work?”
“I checked everything very carefully,” the computer said, “and with all certainty I declare that this is the answer.” It seems to me, if you are absolutely honest with you, then the whole point is that you yourself did not know what the question was.
“But this is a great question!” The final question of life, the universe and all that! - almost howled Lunkkuool.
“Yes,” the computer said in the voice of a sufferer, enlightening a round fool. “And what is this question?”
From Douglas Adams' Hitchhiker's Guide to the Galaxy
- Forty-two! Squealed Lunkkuool. “And that's all you can say after seven and a half million years of work?”
“I checked everything very carefully,” the computer said, “and with all certainty I declare that this is the answer.” It seems to me, if you are absolutely honest with you, then the whole point is that you yourself did not know what the question was.
“But this is a great question!” The final question of life, the universe and all that! - almost howled Lunkkuool.
“Yes,” the computer said in the voice of a sufferer, enlightening a round fool. “And what is this question?”
From Douglas Adams' Hitchhiker's Guide to the Galaxy
The history of the substance of which we are composed
During the big bang, only the lightest elements were formed: 75% - hydrogen, about 25% helium, about 0.01% deuterium and helium-3, 10 -10 lithium, and insignificant fractions of other substances.
Where could everything else come from that surrounds us?
Earth's chemical composition (incomplete)
Answer by astrophysicist Neil DeGrasse Tyson:
English video
In details:
In details:
There were several pathways for the formation of substances, but most are associated with the bowels of ancient stars:
So everything that surrounds us - from ourselves, to leaves on trees, from the air we breathe to minerals in the bowels of the Earth - was once part of the ancient stars that died in supernova explosions have given us life. Our Sun belongs to the third generation of stars.
Our movement in space.
Many are aware that even when sitting still, we move with the Earth, many will be able to name 2 or 3 of these components of the movement, but in fact there are 6 of them:
1) The rotation of the Earth around its axis. Period - 1 stellar day (23 h 56 min 4.1 sec).
This speed depends on the latitude of the area where you are located, and varies from 1674 km / h for the equator to zero for geographical poles (magnetic poles are slightly different from them). However, even while at the pole, you will rotate:
Long exposure photography, La Silla Observatory
Such a “slow” by our standards rotation speed for such a planet as the Earth is quite noticeable - the deviation from sphericity is 21.3 km. Together with the rotation itself, this creates an interesting effect - the acceleration of gravity g at the poles is 9.832 m / s², and at the equator - 9.78 m / s² (with the standard value used for calculations 9.800665 m / s²), so at the equator you will weigh 0.5% less than at the pole. These seemingly insignificant differences are of great importance for missiles - the Soyuz launch vehicle from the Kourou spaceport (5 ° north latitude) can output 25-30% more payload than from the Baikonur cosmodrome (45 ° north), but there are Cosmodromes, which are located further north.
The length of the day gradually increases at a speed of 1 second in 50 thousand years. Therefore, they refused to be bound to the Earth days in the measurement of time back in 1967 - now the second is defined as the time interval for which the cesium-133 atom passes between two ultrathin levels of the ground state 9,192,631,770 times. By the way, the meter has also not been tied to the standards since 1983 - now it is defined as 1/299 792 458 of the distance that light travels in one second. Perhaps by the 2018 meeting of the International Committee of Weights and Measures we will be able to abandon the last anachronism - the weight standard (they want to express it from Planck's constant equal to 6.62606x, where the x value will be determined by the CODATA committee).
2) The next component is the rotation of the Earth around the Sun. Period - 1 sidereal year (365.2564 days)
The earth moves at a speed of 29.78 km / s, this speed increases slightly from July 3 to January 3, and then decreases to its previous level. The orbit of the Earth is very close to circular, due to which the Earth has very small (by cosmic standards) temperature differences.
To determine where we are currently moving, it is necessary to postpone 90 ° to the right from the current position of the Sun (for residents of the southern hemisphere, it will have to be postponed to the left).
The movement of the sun in the constellations:
3) The movement of the solar system relative to stellar neighbors. The period is 66 million years.
This component is 19.4 km / s, and is directed (at the moment) in the direction of the Hercules constellation, on the border with the constellation Lyra, the direction is α = 270 °, β = + 30 ° (hereinafter, the direction is set relative to the galaxy). This component is interesting in that it is directed perpendicular to the plane of the Milky Way, and the Sun either rises above the galactic disk, then falls below it, crossing it every 33 million years.
4) The movement of the Sun around the center of the galaxy. The period is 225-250 million years.
The sun rotates around the center of the Milky Way at an enormous speed of about 220 km / s, but due to its even gigantic radius of 27,200 light years, this is a very slow process. For comparison, primates appeared only 80 million years ago, and during this time only a third of the “galactic year” passed. Our entire history, from the first cave paintings 40 thousand years ago, to the release of a man into space, passed in 0.06 degrees (3.5 arc minutes) of this revolution.
5) The movement of a local group of galaxies.
We are moving relative to the local group at a speed of ≈ 115 km / s, in the direction α ≈ 87 °, β ≈ 69 °. The period of revolution here is already difficult to determine - for this it is necessary to calculate the center of mass of our galaxies, which is incredibly difficult. And then calculate the movements of all galaxies relative to each other - which also does not differ in simplicity ...
6) The last and most fundamental movement remains - the movement of our galaxy relative to space itself, how can we measure it? The theory of relativity postulated that we will not be able to determine the speed of our movement, being in an inertial reference frame.
And there was no way to solve this problem until 1969, when the dipole component was not detected in the relict radiation: The
relict radiation should have been anisotropic in all directions, but in the direction of the Hydra constellation this radiation was “warmer”, and in the opposite direction "Colder." This was the answer to this question, we were able to measure the last component of our movement!
During this time, a long way was taken in the study of CMB, for its study, NASA sequentially sent two space telescopes:
And after that, its telescope Planck sent ESA:
Data from these telescopes allowed us to estimate the speed and direction of movement of the local cluster as 627 ± 22 km / s in the direction l = 276 ± 3 ° longitude, and b = 30 ± 3 ° longitude. It also made it possible to measure the components of dark energy, dark matter and ordinary matter with an accuracy of tenths of a%. It allowed to find out the time of the birth of the Universe - 13.799 billion years with an accuracy of ± 210 million years. Relict pattern of the Planck space observatory of the European Space Agency (clickable)
Astrophysicists based on the data on the motion of the 800 nearest galaxies to us have already estimated the direction and speed of our Milky Way relative to the large-scale structure of the Universe. These data allow us to judge the motion of most galaxies, including ours, towards the Great Attractor - a gravitational anomaly, the composition of which is still poorly understood.
Links:
www.astronet.ru/db/msg/1189375 Sun Movement (astronet.ru)
nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html Sun Information (NASA)
Dipole Anisotropy in the COBE DMR First-Year Sky Maps. The astrophysical journal