More than ten years ago, three Hubble deep space photos really shocked everyone, facing the rather sparse sky area of the stars, Hubble continued to observe for more than ten days, and the faint photons emitted from the celestial body at the other end of the distant universe were left on the ccd, making human beings observe the extremely distant universe from an unprecedented angle!
Hubble has photographed the super deep space field three times, the first time for ten consecutive days from December 18 to 28, 1995, targeting the constellation Ursa Major, covering only 2.6 arc minutes wide and one-size-per-millionth of the area of the whole day;
Only a few prospective objects in this deep space photo are stars in the Milky Way, and NASA scientists have found many redshifts up to 6 objects, which indicates that these objects are located 12 billion light-years away, unlike the distant universe that scientists imagine to be "cold and clear".
The second deep space illumination in the Southern Celestial Region between September and October 1998, about 3,000 galaxies are located 12 billion light-years away, Rhododendron, equatorial longitude 22h32m56.22s, declination -60° 33'02.69 ", it is similar to the conditions observed in the Northern Constellation Ursa Major, but the sky region without the Milky Way and the moon and the Earth itself can be exposed for a long time.
The truly farthest ultra-deep space photograph was taken between September 24, 2003 and January 16, 2004, covering a 3-square-angle minute, with an area of only one-twelfth of the whole sky, located in a small area of the solar hearth of 3h 32m 40.0s equatorial longitude and -27°47' 29" (j2000) of the celestial furnace seat.
That's the equivalent of 113 days of exposure, and the photo shows more than 1,000 galaxies, all located 13 billion light-years away!
The last was the Hubble Extreme Deep Space Photograph, which was released on September 25, 2012, but instead of retaking it, Hubble reprocessed the images taken over the past 10 years, adding about 5,500 galaxies to the ultra-deep space photographs taken between 2003 and 2004, and the farthest observed information was as far as 13.2 billion light-years.
It is chilling to find that the distant universe is still so bustling and seemingly endless, where is the end of the universe? Can we see the end?
Wanting to see further, is hubble still going?
Of course, with a longer exposure, this can collect more distant photons, such as exposure for 1000 days, but obviously impossible, due to the redshift of many galaxies emitted by the light has been out of the visible light, into the infrared band.
Hubble Deep Space and Hubble Ultra Deep Space take depth diagrams
So NASA's new generation of telescopes, the James Webb telescope, is in the sky, its reflective mirror surface is made of beryllium, the coating is an extremely thin layer of gold, the observation band has been biased towards the red and infrared bands, and the official data is: 0.6 microns (orange) to 28.5 microns (mid-infrared). Because of the expansion of the universe, the celestial bodies that formed early in the birth of the universe have become extremely redshifted, and only James Webb can see it.
Farther away can only be observed in the electromagnetic band, because the redshift has entered the electromagnetic band, and these celestial bodies can only be observed by radio telescopes, and many radio bursts can only be observed by radio telescopes.
But even if it's an electromagnetic wave observation, At most, you can only see the microwave background radiation formed about 375,000 years after the Big Bang, because the newly born universe is dense, high temperature, full of white-hot hydrogen cloud plasma plasma, plasma and radiation fill the entire universe, only after the expansion of the universe gradually cooled, photon decoupling can be shuttled in the universe, the limit of modern observation equipment is here, whether it is optical or radio band, they all have an extreme earliest time of photon occurrence, that is, the moment of photon decoupling.
From the birth of the universe to 375,000 years, is there no other means of observation? Of course, neutrinos can, although its penetration is extremely strong, can penetrate almost all objects, but scientists can still effectively observe.
With neutrino observations, it can approximately 1 second after the Big Bang, which is the moment after the neutrino decoupling, the neutrino no longer interacts with baryonic matter, and the temperature of the universe at this time is about 10 billion Kelvin.
If we can detect neutrinos from this moment, then we will get the universe 1 second after the Big Bang, which is believed to be the cosmic moment that scientists want to know.
However, scientists have simulated the moment of about 10^-12s of the birth of the universe in the laboratory, using the Relativistic Heavy Ion Collider at Brookhaven National Laboratory in New York, which reached a temperature of 4 trillion Kelvin when the gold ions collided in 2010, which is about 10^-12s after the birth of the universe.
The only means of observing the moment of the universe's birth: the gravitational waves discovered by Einstein
From the birth of the Big Bang universe to the modern universe, the theoretical limit of optical observation is microwave background radiation, the limit of neutrino observation is one second after the birth of the universe, and then the medium carrying information can only be gravitational waves!
This gravitational wave is a phenomenon predicted by Einstein shortly after the birth of general relativity, and it was not really observed until 1916, not because our method is wrong, but because the accuracy is too high, and the Weber rod of that year can also detect gravitational waves theoretically, but the theoretical change limit is too small, we simply do not monitor it.
Only later laser interferometer gravitational wave observatories (ligo) mature technology has been able to detect gravitational waves! Gravitational waves are a kind of material wave produced by the violent movement and change of matter and energy, the propagation speed is also the speed of light, the gravitational wave wavelength of 150hz is 2000 kilometers, in order to meet the detection requirements, Ligo's 4 kilometer detection arm needs to be amplified by 100 times, which is not difficult, and the technology used to reflect multiple times is magnified by hundreds of times.
Of course, this can only detect the gravitational waves of black hole mergers, and later improved and also found the gravitational waves of neutron star mergers, but even the improved ligo can only detect gravitational waves at 10hz, if you want to detect gravitational waves of lower frequencies, then you must achieve a longer interference arm gravitational wave observatory.
You can calculate the wavelength according to the gravitational wave frequency, and then calculate the wavelength of the laser interferometry arm according to the target detection wavelength of ligo, you will find that this interference arm is simply too scary, such as the space laser interferometer that is now in full swing (China's Lyra and Taiji plan, Europe and the United States Lisa) can only detect short-period double stars, extreme mass proportional rotation, supermassive black hole double stars and other gravitational waves, and some can reach the state of the Big Bang gravitational wave monitoring.
The real Big Bang gravitational wave detection level is 10^-18 ~10^-15hz, this wavelength is too terrifying, the need for microwave background radiation observation to find traces of gravitational waves and then analyze gravitational waves, this requirement is too perverted
What state can gravitational waves observe the Big Bang?
10^-43 seconds after the Big Bang (Planck time): The cosmic temperature is about 10^32 degrees, and the universe was born from the background of quantum fluctuations, a stage called Planck time.
At this moment, the universe has cooled to the point where gravity can separate and exist independently, and the other forces in the universe (strong, weak and electromagnetic interactions) are still a paste, so theoretically, gravitational wave detection can understand the situation after the Planck time when the universe was born, and touching this moment must be the moment that countless scientists have exhausted their lives to understand.
Summary: Where exactly can we see?
The observable radius of the universe is about 46.5 billion light-years, which is the theoretical diameter calculated from the Big Bang theory and many other data such as inflation and the Hubble constant, and from this point of view, the objects we can see are probably the following data:
The farthest galaxy visible to the naked eye is said to be the Triangulum Galaxy, which is about 3 million light-years away
The local group of galaxies in which the Milky Way is located is about 10 million light-years in size;
The Virgo Supercluster in which the local group is located ranges about 100 million light-years;
Further up, the Raniakea Supercluster, about 500 million light-years in diameter;
Larger is the Pisces-Cetus supercluster complex, which is about 10 billion light-years in diameter;
Astronomers can now observe the farthest objects at a distance of about 30 billion light-years;
Cosmic microwave background radiation is about 46.1 billion light-years away;
If it is a gravitational wave, it will probably reach the core of the Big Bang, 46.5 billion light years;
So if we want to see farther, we have to use means that are detached from visible light, and for now, neutrinos and gravitational waves are the only two means.
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