synonymCosmic microwave background radiation(Cosmic microwave background radiation) generally refers to background radiation
Background radiation (in English: CMB, thermal microwave background, also known as 3K background radiation) iscosmologyLeft over from the "big bang"electromagnetic waveRadiation is a kind ofBlackbody radiation(thermal radiation).In the early literature, "cosmic microwave background" is called "cosmic microwave background radiation" (CMBR) or "leftover radiation", which is a kind of radiation that fills the whole universeelectromagnetic radiation, and similarPrimary gravitational waveIs the legacy of the "Big Bang"Gravitational waveRadiation.
The cosmic background radiation is fromCosmic spaceContextualIsotropyOfmicrowave radiation, also known as microwave background radiation.At the beginning of the 1960s, American scientists Pennzias and RW. Wilson to improveSatellite communication, established high sensitivity horn type receptionantenna system。In 1964, they used it to measureSilver haloGas radio intensity.To reduceClutterThey even cleared theBird droppings, but there is still something that cannot be eliminatedCentimeter wavebackground noise 。They believe that the microwave noise with a wavelength of 1.875 from the universe is equivalent to 3.5K.In 1965, they revised it to 3K, and made this discovery known to the world. For this reason, they were awarded the title ofThe nobel prize in physics。
Features andAbsolute temperature scale2.725KBlackbody radiationSame.Frequency belongs to microwaveMillimeter waveRange.The cosmic microwave background is one of the cosmic background radiationObservational cosmologyBecause it is the oldest light in the universe, it can be traced back to the recombination period.Utilize traditionalOptical telescope, stars andGalaxyThe space between (the background) is dark.However, the weak background glow can be found with a sensitive radiation telescope, which is almost identical in all directions, and has nothing to do with any star, galaxy or other object.This kind of lightElectromagnetic spectrumIn microwaveCentimeter waveThe region is the strongest.1964 American RadioastronomerArno Penzias andRobert WilsonAccidental discovery of cosmic microwave background[1-2], started research in 1940s, and obtainedNobel Prize。
"The cosmic microwave background is the oldest light in our universe. When the universe was just 380000 years old, it was in the sky. It showed tiny temperature fluctuations, corresponding to the subtle differences in local density, representing all future structures, and is the seed of today's stars and galaxies".[3]
The cosmic microwave background well explains the radiation left by the early development of the universe, and its discovery is considered as a detectionBig Bang Cosmic ModelMilestones for.When the universe was young, before stars and planets formed, it contained dense, high-temperature, and white hot hydrogen cloudsPlasma。Plasma and radiation fill the whole universe, and gradually cool with the expansion of the universe.When the universe cools to a certain temperature, protons and electrons combine to formNeutral atom。These atoms no longer absorb heat radiation, so the universe gradually becomes clear, no longerOpaqueThe clouds and mist of.CosmologistIt is proposed that the neutral atom is formed in the period of "recombination", and immediately after the "photon decoupling", that is, the photon begins to travel freely through the whole space, rather than in the period ofPlasmaMedium tight collision.Photons begin to propagate after decoupling, but due to space expansion, the wavelength increases with time (according toPlanck's law, the wavelength is inversely proportional to the energy), the light becomes weaker and weaker, and the energy is also lower.This is the source of the other name "legacy radiation".The "final scattering surface" refers to theRadioactive SourceThe collection of the source points of the received photons in space.
Because any establishedCosmic modelMust be explained, so the cosmic microwave background is an accurate measurementcosmologyThe key to.The temperature of the cosmic microwave background in the blackbody radiation spectrum is 2.72548 ± 0.00057K.[4]Spectral radiation dEν/dνThe peak value of is 160.2GHzMillimeter waveWithin the frequency range.(If the spectral radiation is defined as dEλ/dλ，bePeak wavelengthIs 1.063 mm.)
This brilliance is almost identical in all directions, but slight residual changes showanisotropyAs expected, the fairly evenly distributed hot gas has expanded to the size of the universe.In particular, spectral radiation at different angles in the sky contains the same anisotropy, orIrregularity, which varies with the area size.They have been measured in detail. If there is a small temperature change caused by the quantum perturbation of matter in a very small space and it expands to the observable size of the universe, it should be consistent with it.This is a very active research field, and scientists are looking for better data (for example, Planck satellite) and betterCosmic expansioninitial condition 。Although many different processes can produce the general form of blackbody radiationBig Bang ModelIt can better explain fluctuations.Therefore, most cosmologists believe that,Big BangThe model can best explain the cosmic microwave background.
There is a high degree of consistency in the entire visible universe, and the dim but measured anisotropy widely supports the Big Bang model, especially the Λ CDM model.In addition,Wilkinson Microwave Anisotropy DetectorandPolarization Background Imaging of Cosmic Pan GalaxiesThe experimental observation distance is greater than the recombination periodCosmic horizonAngular scale fluctuatingrelevance。This correlation may be a non causal fine-tuning, or due to cosmic inflation.[5-6]
features
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Background radiation
The most important feature of microwave background radiation isBlackbody radiationSpectra, in the 0.3 cm - 75 cm band, can be measured directly on the ground;At the height of more than 100 cmRadio band，GalaxyOf itselfUHF radiationIt covers the radiation from the extragalactic space, so it cannot be directly measured;In the wave band less than 0.3 cm, due to the EarthAtmospheric radiationInterference, depending on balloons, rockets or satellitesSpace explorationMeans can measure.The measurement in the wave band from 0.54 cm to tens of cm shows that the background radiation is near 2.7KBlackbody radiation, customarily referred to as 3K background radiation.Blackbody spectrumThe phenomenon shows that the microwave background radiation is an event in a large space-time range.Because only through radiation and materialInteraction, can formBlackbody spectrum。Due to the extremely low density of matter in today's cosmic space and the minimal interaction between radiation and matterBlackbody spectrumIt must have originated a long time ago.The microwave background radiation should be more than that of distant galaxies andRadio sourceCan provide more ancient information.Another characteristic of microwave background radiation is that it has extremely highIsotropy。This has two implications: firstsmall scaleOnIsotropy。In the range of dozens of arc minutes,radiation intensityThe fluctuation of is less than 0.2-0.3%;The second islarge scaleOnIsotropy。alongcelestial sphereThe fluctuation of radiation intensity in different directions is less than 0.3%.IsotropyIt shows that in different directions, there should have been mutual relations between the very distant sky regions.
The universe is full of temperature just over 2.7 degrees Kelvin, which can use the groundradio telescopeandArtificial satelliteThe instrument on the detected the sea of radiation.This is interpreted as the big bang fireball from which the universe was borndirect evidence。Therefore, the discovery of background radiation is fromEdwin Hubble Since the discovery of cosmic expansioncosmologyThe most important observation achievements in;However, this discovery was hard won.
From the background radiation, useDoppler effectSubtract onedipoleThe latter is due to the fact that the earth is stationary relative to the co moving universeFrame of referenceThere is relative motion, and the planet moves towards Leo at a speed of 371 km/s.After the dipole is subtracted, the cosmic microwave background is uniform radiation, and the heat energy of black body radiation comes from the whole sky.Radiation is isotropic, the difference is about 1/100000: the root mean square variation is only 18μK[7]The cosmic microwave background dipole and the difference in higher order multipolar moments have been measured, and the results are consistent with the impact of the motion of the Milky Way.[8]
The universe formed under the Big Bang model,Inflationary universeIt is predicted that the newborn universe will grow exponentially in about 10 seconds, smoothing almost allNonuniformity。The rest of the inhomogeneity is caused by quantum perturbation in the inflationary field, which leads to cosmic inflationary events.After 10 seconds,Early universeIt is composed of high temperature, electrons, protonsbaryonIt is composed of plasma interacting with photons.When the universe expands,Adiabatic coolingPlasmogenicenergy density Lower until the environment becomes conducive to the combination of electrons and protons to formhydrogen atom。When recombination occurred, the temperature was about 3000 K, and the universe at that time was about 379000 years old.At this point, photons are no longerElectroneutralityAtoms interact with each other and begin to travel freely in space, causing matter and radiation to retreatcoupling。[9]
The color temperature of uncoupled photons has gradually decreased to 2.7260 ± 0.0013 K. With the expansion of the universe, its temperature will continue to decline.According to the Big Bang model, the measured sky radiation comes from a sphere called the "final scattering surface".This is the occurrence of decoupling events predicted in space and just transferred toObserverOf photons ofpoint of timeThe collection of points for.All in the universeradiant energyIt is cosmic microwave background radiation, which makes up about
The total density of the universe.[10]
Big Bang TheoryThe two greatest achievements ofEnergy spectrumAnd its detailed prediction of the cosmic microwave background radiationanisotropy。The cosmic microwave background spectrum has become the most accurately measured blackbody radiation spectrum.
anisotropy
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The anisotropy of the cosmic microwave background can be divided into two types: the initial anisotropy, which is derived from the final scattering surface andOccurred beforeImpact of;And second-order anisotropy, which is due to the radiation interaction with the background hot gas orGravitational potential energyInfluence, which occurs between the final scattering surface andObserverbetween.
The anisotropic structure of the cosmic microwave background radiation is mainly due to two influences: diffusion damping (also known asCollision damping）。Because photons-baryonstayEarly universeOfPlasmaCaused by collision.Photon pressure tends to eliminate anisotropy, while gravity attracts baryons - movingSpeed ratioPhotons are much slower -- they tend to collapse to form densea quasar。These two effects compete to create a peak structure that gives microwave background radiation characteristics.These peaks roughly correspond to and resonate with a mode in which the photon is decoupled at the time of peak amplitude.
These peaks contain interesting physical characteristics.The angular scale of the first peak determinesCosmic curvature(but not cosmic topology).The next peak, the ratio of odd peak to even peak, determines the limiting baryon density.The third peak can be used to obtaindark substanceDensity information.[11]
The position of the peak also gives the initialDensity perturbationImportant information about weight.There are two basic types of density disturbances, called "adiabatic" and "etccurvature”。The general density disturbance is a mixture of the two. Different theories hope to explain the energy spectrum of the first order density disturbance and predict different mixing modes.
Adiabatic density perturbation
The proportion of extra density for each type of particle (baryons, photons...) is the same.In other words, if more than 1% of the baryon energy in a place is greater than the average, then there is also more than 1% of the baryon energy in that placePhoton energy(and more than 1%neutrinoEnergy) above average.The first order perturbation predicted by cosmic inflation is adiabatic.
Constant curvature density perturbation
Extra at each place (all different types of particles)Density ratioThe sum is zero.That is, if the baryon energy perturbation at a certain point is more than 1% of the average, then the photon energy is more than 1% of the average, and 2% of the neutrino energy is less than the average, which is a pure equicurvature perturbation.Cosmic stringMost first-order disturbances with equal curvature will be generated.
The cosmic microwave background spectrum can distinguish these two types, because these two types of disturbances will produce different peak positions.The equicurvature density disturbance will produce a series of peaks, and the ratio of its angular scale ("l", the number of peaks) is about 1:3:5:..., while the position of the peaks produced by the adiabatic density disturbance is 1:2:3:... The observation results are completely consistent with the adiabatic in the first order density perturbation, providing key support for the explosion, and excluding many theories of structure formation, such as cosmic strings.
Collision damping comes from two aspects. When the initial plasma fluid starts to be broken:
As the plasma becomes thinner and thinner in the expanding universe, the average free path of photons will increase.
Finally, the depth of the scattering surface (LSS) is limited, which results in that even Compton scattering still occurs during decoupling, and the average free path suddenly increases.
These effects help to suppress the small scale anisotropy and lift the characteristic exponential attenuation tail of the small angular scale anisotropy.
The depth of LSS is that the decoupling of photons and baryons will not meet instantaneously, but need a considerable proportion of the age of the universe at that time.One way to quantify this process is to use the "Photon Visibility Function (PVF)".This function is defined as P (t) for PVF, and the probability of the last scattering of cosmic microwave background photons between time t and t+dt is P (t) dt.
PVFMaximum(Given the most likely scattering time of cosmic microwave background photons) is known to be quite accurate.The maximum P (t) of WMAP's one-year results is 372000.This is usually regarded as the "time" of the formation of the cosmic microwave background.However, in order to understand how long it takes for photons to decouple from baryons, we must measure the width of the PVF.The WMAP team found that PVF was greater than half of its maximum value ("half height and full width", or FWHM) for more than 115000 years.According to this measurement, decoupling occurred for more than 115000 years, and when it was completely decoupled, the universe was about 487000 years old.
Since the cosmic microwave background began to exist, it was obvious thatphysical process Influence is collectively referred to as post anisotropy, or secondary anisotropy.When the cosmic microwave background photons travel freely, ordinary matter in the universe is mainly in the form ofNeutral hydrogenandHelium atom。However, current observations of galaxies seem to indicate that mostInterstellar mediumThe volume of (IGM) is determined byhydrogen atomAbsorption line）Composition.That means there's aReionizationDuring this period, some cosmic matter was broken up intoHydrogen ion。
Cosmic microwave background photons arefree electronScattering, so that electrons are not bound to atoms.In the electrolytic universe, thesecharged particleExcuse dissociation（ultraviolet rays）Radiation fromNeutral atomChina has been liberated.these ones hereFree chargeThere are enough low densities in all volumes of the universe to no longer affect the cosmic microwave background in measurable quantities.However, if IGM is very early, the universe is still inhigh-densityWhen it is ionized, it will have two main effects on the cosmic microwave background:
one
Small scale anisotropy is eliminated.(It's like seeing things through fog. The details of the object are blurred.)
two
The physical mechanism of how photons and free electrons scatter (Thomson scattering) leads to large angular scale polarization anisotropy.This wide-angle polarization is related to wide-angle temperature disturbances.
These effects have been observed by WMAP satellite, and the evidence provided shows that the universe was free when the redshift exceeded 17 in the very early stage.This earlyionizing radiationThe detailed provenance of is still a controversial scientific debate.It may have included starlight from the first stars（The third star family）, theseFirst generation starsAt the end of their livesSupernova explosion, or byMassive black holeAccretion diskIonizing radiation generated.
The time from the launch of the cosmic microwave background to the observation of the first star is called the dark age of the universe (see21cm line）。
The two other effects that occur between the re ionization and the cosmic microwave background we observed, and their effects on anisotropy areSunyaev Zeldovich effect, of which high energyElectronic cloudScatter the radiation and transfer the energy of some cosmic microwave background photons;And the Sax Waffle effect, which results in the cosmic microwave background radiation of photons due tofield of gravityChangeGravitational redshift Or blue shift.
polarization
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The cosmic microwave background is located in several microAbsolute temperatureThe layer of is polarization.There are two types of polarization, E-mode and B-mode.This situation is analogous toElectrostatics。In electrostatics, thecurlIs zero, the magnetic field ("B" field)divergenceIs zero.In heterogeneous plasma, EMemeThomson scatteringNaturally occurring.B-mode not yetMeasured, is consideredamplitudeMaximum should be 0.1μK. Not byPlasma physicsGenerate.B module is not from standardscalarPerturbation comes from two mechanisms.The first is from beingGravitational lensE mode, which was adopted in 2013Antarctic ObservatoryMeasured.[12]The second is from the expansion of the universeGravitational wave。It is extremely difficult to detect "B" mode, especially when the foreground pollution is unknown and weakGravity lensThe signal mixes the strong E-mode signal with the B-mode signal.[13]
forecast
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In 1934, Tolman found that the temperature would change with time in the evolution of radiation temperature in the universe;The frequency of photons evolves with time (i.e. cosmologyred shift）It will also be different.But when both are considered together, that is, when discussing the spectrum (a function of frequency and temperature), the changes of both will be offset, that is, the form of blackbody radiation will remain.
In 1948, American physicists Gamov, Alfie and Herman estimated that if the initial temperature of the universe was about 1 billion degrees, there would be about 5-10k black body radiation left.However, this work has not attracted much attention.In 1964, Zerdovich of the Soviet Union, Hoyle of Britain, Taylor, Peebles of the United States and others predicted that the universe should remainWith temperatureIs the background radiation of several K, andCentimeter waveThe above section should be observable, which has aroused the attention of the academic community to the background radiation again.AmericanDick(Dicke), Roll, Wilkinson and others also started to build a low-noise antenna to detect this radiation. However, American radio astronomers Penzias and Robert Wilson accidentally discovered the background radiation before them.
The first person who tried to quantitatively describe the physical conditions of the Big Bang was George Gamov.He used it in the 1940sQuantum physicsHe studied the type of nuclear interaction that should have occurred when the universe was born. He found that the original hydrogen should have been partially transformed into helium (seeαβγtheory）。
According to calculations, the amount of helium produced in this way depends on the temperature of the Big Bang when these interactions occur.It should beX-rayandγradialShort wave of formBlackbody radiationFireball filling.Gamov group realized that the thermal radiation corresponding to this fireball should have been diluted and cooled with the expansion of the universe, but it is still highred shiftOfRadio waveMorphological existence.
Since there is no place outside the universe for this radiation to escape, it will always fill the universe, just like the gas inside the balloon will always fill the balloon.If the balloon is pulled to make it larger, but no more gas is allowed to enter, the density of the gas inside the balloon will become smaller.Similarly, whenCosmic expansionThe density of the radiation that fills it will also become smaller.This corresponds to the decrease of temperature and the increase of radiation wavelength——red shift。However, although the radiation has cooled, it should still fill the universe as evenly as the gas filled with balloons.It should illuminate the earth from all directions in space, and the amount of radiation wavelength being pulled apart due to the expansion of the universe determines its temperature today.
Ralph, Gamov's two students·AlfieAnd Robert·Hermann——It was calculated in a paper published in 1948 that the amount of helium "cooked" in the Big Bang should matchspectroscopyRevealedOld starThe amount of helium in, and the radiation left by the Big Bang fireball should now have a temperature of only 5K.Gamov himself published a slightly larger number in his book "Creation of the Universe" in 1952.
The exact number depends on the detailed assumptions made about the physical conditions of the Big Bang, and also depends on theCosmic ageEstimate of.A manual calculation method is that the background radiationKelvin temperatureIt is equal to (1 followed by 10 zeros) divided by the square root of the age of the universe in seconds.Therefore, the temperature is 10 billion degrees one second after the time starts, 1 billion degrees one hundred seconds later, and only 170 million degrees one hour later.In contrast, the temperature of our solar center is about 15 million degrees.
But neither Gamov nor his colleagues realized that the technology of taking the temperature of the universe had existed since the 1950s.They neither urged radio astronomers to make observations that could have revealed the existence of background radiation, nor did any radio astronomer seem to have noticed the article predicting the existence of such radiation.Strangely, however, it shows thatCosmic temperatureThe observation very close to 3K has been used in the 1930sSpectral methodIt's done.
It was a spectral observation of a compound called cyanogen (CN), which revealed thatInterstellar matterThe temperature of the cloud.In 1940,CanadaDominionAstrophysicsAndrew McKellar of the station explained these observations and concluded thatInterstellar cloudThe temperature of is about 2.3K.By 1950, this result had been written into standard textbooks.But even Gamov didn't compare it with the background of the prophecyRadiation temperatureConnect.One of the reasons is that Gamov's own estimated temperature is higher than the temperature andAlfieandHermannThe estimated temperature is much higher.
1981 Fred·HoyleOn《New scientist》In an article published, he described in detail how he mentioned Mike when talking with Gamov in 1956KellerScenario for calculating results.HoyleyesSteady stateA passionate supporter of the hypothesis, he did not believe that there had been a big explosion, so he believed that there was no background radiation.Gamov believes that there should be a background radiation whose temperature is much higher than 5K.HoyleRemember he pointed out to Gamov that MikeKellerAn upper limit of 3K has been set for any such background radiation, so Gamov is wrong.The imagination of both of them failed to take a big step after the accident, so they did not realize that background radiation was indeed everywhere, but its temperature was lower than that of GamovEstimated value。
What's more strange is that just as the Gamov research group developed their ideas in the 1940s, a group of radioastronomerWe are actually searching for low-temperature radiation from space.Robert·Dick And his colleagues used an instrument evolved from wartime radar technology toCentimeter waveThe frequency band studies the sky and finds that the temperature is lower than 20K, which is the limit specified by the instrument - evidence of radiation.Their results were published in the journal Physical Review (70 volumes, 340 pages) in 1946, and the first paper of Gamov Research Group on nuclear synthesis (70 volumes, 572 pages) was also published in the same volume - but it will take almost 20 years for anyone to connect them.
Joint team
By the early 1960s, several research groups, including the United States, Britain andSoviet UnionThe scientists of, have begun to consider how to detect the residual radiation of the Big Bang - the pioneering work of Gamov Group has been basically forgotten, and each group has seen the possibility again.stayPrinceton University , a young scientistJames Peebles(P.J.E. Peebles) repeated unknowinglyAlfieandHermannAfter doing the calculation, I realized that the universe should be full of a sea of background radiation with a temperature of several degrees Kelvin.Dick, his tutor in this work, also forgot his own pioneering achievements in the 1940s, but appointed two other researchers, P.C. Roll andWilkinson(D.T. Wilkinson) - Build a smallradio telescopeTo search for this radiation.
Of course, that is background radiation.Theory and observation have finally come together.Two two person teams immediately jointly tackle key problems.
The Princeton team quickly confirmed these observations.The papers of the two groups are published in《Journal of Astrophysics》On.In the next 20 years or so, more and more observations, using various instruments, have proved the existence of background radiation in many wavebands, fixed the temperature at 2.7K, and proved that it isBlackbody radiation。PenziasAnd Wilson were promised in 1978 due to this accidental discoveryBellAward.It is the discovery and interpretation of background radiation that makes most astronomers admit that there was a big explosion, and it also madecosmologyIt has become a thriving discipline, and it also promotes the celestial bodiesphysical scientistStudy other phenomena related to the Big Bang, such asPrimary gravitational wave。
puzzled
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Before the 1980s, there was still a puzzling problem related to background radiation.Radiation from all directions in space has exactly the same temperature, which is too smooth.
The Big Bang theory, which has been reliably proved, believes that this radiation should not have changed since the moment about 300000 years after the birth of the universe（red shiftAnd cooling).And 300000 years after the birth of the universe, the entire universe cooled to about 6000K, which is roughly the temperature of the sun's surface.At that temperature, individual electrons and nucleons can combine to form stable atoms without anyNet charge。Because atoms are electrically neutral, they cannot interact withelectromagnetic waveStrong interaction, so the background radiation has not been disturbed since then.
If the universe is completely smooth 300000 years after its birth, as suggested by the smoothness of background radiation, where do galaxies, stars and humans come from?If we want to exist, the universe must have some irregularities before it reaches 300000 years old -Gas cloudUnder their own gravity, they should soon gather and collapse to form galaxies and stars.
theory
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The theory claims that the result of these irregularities is that there should be ripples in the background radiation, that is, when the instrument points to different parts of the sky, the temperature should be slightly different.The difference of prediction is very small, only from the higherEarth's atmosphereDisturbance in space for measurement.In April 1992, NASA announced COBE（Cosmic backgroundExplorer) satellite found the ripple, which is just the size of the standardBig Bang ModelExact coincidence of predictions.The discovery was hailed asBig Bang TheoryIt confirmed that the universe really originated at a certain time in a fireball of thermal radiation.Therefore, one result of the way the universe was born is that it is full ofCentimeter waveThe microwave background radiation ofMicrowave OvenBut its cooking temperature is quite low, a little lower than - 270 ℃.
Data analysis
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Satellite's original cosmic microwave background data (such asWMAP）Including foreground effect, it will completely cover up the fine scale structure of the cosmic microwave background.The fine scale structure is superimposed in the original cosmic microwave background data, which is too small to be reflected by theraw dataAppears in.The most prominent foreground effect is caused by the movement of the sun relative to the cosmic microwave backgrounddipoleanisotropy。Due to the dipole anisotropy and the fact that the earth is relative to the sunGalaxyPlanarMicrowave sourceAnd elsewhereAnniversary campaignAnd others must be subtracted to reveal ultra subtle changes and describe the fine scale structure characteristics of the cosmic microwave background.
The limits on many cosmological parameters can be set by themEnergy spectrumThe results are often obtained byMarkov Monte CarloSampling technology calculation.
According to theCosmic background finder(COBE, Cosmic Background Explorer), the background radiation spectrum is very accurately consistent with the black body radiation spectrum at 2.726 ± 0.010K, which confirms that the Milky Way has a relativeMovement speedAnd also verify that the speedmeasurement result The cosmic background radiation is highly isotropic, and the amplitude of temperature fluctuation is only about 5 parts per million.The accepted theory is that this temperature fluctuation originated from the extremely small scalequantum fluctuation It is magnified to the cosmological scale with the expansion of the universe, and it is precisely because of the fluctuation of temperature that the distribution of matter in the matter universeNonuniformityAnd finally form a kind of galaxy clusterLarge-scale structure。
In 2006, American scientist in charge of COBE projectJohn MatherandGeorge SmootHe won the Nobel Prize in Physics for his "blackbody form and anisotropy of cosmic microwave background radiation".
Wilkinson Microwave Anisotropy Detector (WMAP)
In 2003, the Wilkinson Microwave Anisotropy Detector launched by the United States measured the fluctuations of the cosmic microwave background in different directions, indicating that the age of the universe is 137 ± 100 million years. Among the components of the universe, 4% are ordinary matter, 23% are dark matter, and 73% are dark matterDark energy。The expansion rate of the universe is 71 kilometers per secondMillisecond gapThe universe is almost flat. It has experienced inflation and will continue to expand.
Planck's Sky Patrol isEuropean Space AgencyThe third medium-sized science program in Vision 2000.hersdesign goal With an unprecedented high sensitivity angleAnalytic forceObtain the anisotropy map of the cosmic microwave background radiation in the whole sky.Planck Sky Patrol will provide severalCosmology and AstrophysicsFor example, testing the theory of the early universe andCosmic structureOrigin of.Enterprises before the plan is approvedDrawing caseThe name is CosmicBackgroundRadiationAnisotropySatellite and Satellite for Measurement of Background Anisotropies. (abbreviated as COBRAS/SAMBA). After the mission was approved, it was changed to the current name in memory of being obtained in 1918Nobel Prize in PhysicsGerman scientistsMax Planck （1858-1947）。Planck Sky Patrol was launched on May 14, 2009 by Arian V rocket and HerschelSpace ObservatoryLaunch together.This is the case with the United StatesAerospaceThe bureau's cooperation plan will complete the WMAP detector measurementlarge scaleRippledeficiencies。[14]
