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Early Edition Age of the Universe: Cosmic Times Size of the Universe: 10-25 Billion Years 1965 25 Billion Light Years

Murmur of a Bang stronomers have found a mysterious cosmic radio Asignal that is as old as the birth of the universe. This is the first direct evidence that the uni­ verse began with a Big Bang. It also gives us clues about how the universe might end.

The newly discovered radio sig­ nal is very faint. It is in the form of microwaves, which is a part of the electromagnetic spec­ trum. Microwaves are between radio waves and infrared light on the electromagnetic spec­ trum. These microwaves in space come from every direc­ tion of the universe, every hour

of every day. This is the exact Image Credit: Bell Labs wavelength some scientists Robert Wilson (left) and Arno Penzias stand in front of their antenna in Holmdel, predicted they would find if the New Jersey. They discovered a radiation signal that matches a signal astrono- universe started in a Big Bang. mers expected if the universe began with a hot explosion called the “big bang.” The Big Bang, a giant explosion This discovery was made by accident as they tried to track down the source of of hydrogen about seven billion unwanted noise in their receiver. years ago, would have been extremely hot and would have steadily cooled since then (ev­ wave signals that a 20-foot horn- erything warmer than “absolute Two scientists, Arno Penzias antenna in Holmdel, N.J. was zero” gives off some kind of elec­ and Robert Wilson, found what picking up. tromagnetic radiation). If there they call “cosmic background was a Big Bang, then some of radiation” by accident. The two When the Holmdel horn was that radiation, detected as mi­ men work at Bell Laboratories aimed directly overhead (called crowaves, would still be found in and were trying to find out what the zenith), Penzias and Wilson space today. was causing unwanted micro­ found a microwave signal that “Murmur” continued on page 2

2 “Murmur” continued from page 1 hot, very dense fireball of matter matched the temperature of 6.7 and energy that existed during degrees Kelvin. After subtracting the early universe would have Big Hiss microwave radiation that is found been about 10 billion degrees in Earth’s atmosphere, and ra­ Kelvin, he said. The extremely Missed by Others diation from the antenna itself, hot beginning of the universe, he they were still left with an unex­ said, would explain the heat that ne of the biggest sur­ plained microwave radiation that still remains in space today. prises that came from matched 3.7 degrees Kelvin. Othe new discovery of the The antenna was aimed at emp­ While this is an amazing discov­ Big Bang’s background radiation ty space, so they had no expla­ ery, some astronomers were not is how many times other people nation for the radiation. Empty surprised. After all, in the late have missed the radiation. space should be absolutely cold, 1940s, George Gamow, Ralph “absolute zero,” or zero degrees Alpher, and Robert Herman al­ Just last year, Russian scien­ Kelvin. But it wasn’t. ready said there had been a “Big tists Andrei Doroshkevic and Igor Bang” and that the heat from Novikov published a study on the Luckily, just down the road from it should still be detectable in physics of the Big Bang. They Bell Laboratories, at Princeton space. In 1949, Alpher and Her­ guessed that if the bang had hap­ University, other scientists had man recalculated some of Gar­ pened, then there would be left­ the answer. Astronomer Robert now’s earlier calculations and over heat between one and ten Dicke and his team were build­ predicted that this heat, this cos­ degrees Kelvin. They even said ing a telescope that could detect mic background radiation, would sky temperature measurements “cosmic background radiation.” now have a temperature of “a could be used from 1961 mea­ When they heard about the mys­ few degrees Kelvin.” It looks like surements taken from Edward terious microwaves that Penzias they were right. Ohm to find this remaining heat. and Wilson found, they knew it In an ironic twist, Ohm gathered was just what they were looking But Alpher and Herman were his information from the Holmdel for. The two teams discussed also partially wrong. They Horn antenna. This is the same the find, then announced the thought they would not be able to antenna astronomer Robert Dicke discovery in a pair of letters that detect the cosmic radiation back­ and his team, along with Arno Pen­ were published in the July issue ground because of starlight and zias and Robert Wilson recently of “Astrophysical Journal.” radiation from other objects in used to find the 3.5 degrees Kel­ space. But this is not so. It looks vin cosmic radiation background Robert Dicke and his team wrote like the Big Bang has cooled off left behind from the Big Bang. But about the cause of the cosmic in a very specific way that chan­ Doroshkevic and Novikov didn’t background radiation. The very nels the energy into specific know that the radiation readings wavelengths of radiation. Dicke from Ohm’s measurements were and his team suspected this, so from space. Because of Ohm, - they were planning on looking they thought it was from the an­ for microwave radiation. This is tenna itself. also why they knew, right away, that Penzias and Wilson’s unex­ Ohm had identified in his data plained microwave radiation was what seemed to be 3.3 degrees a huge discovery. Kelvin background radiation. He figured it was from the antenna. The discovery of cosmic mi­ Because Penzias and Wilson crowave radiation was exciting had the job of subtracting away for some scientists who study the antenna’s own microwave ra­ the universe, but not for others. diation, they were able to say that Cosmic radiation background the faint radiation really did come supports the Big Bang Theory, from space.

Image Credit: AIP Emilio Segre Visual Archives, Physics Today Col lection but causes big problems for the Robert Dicke “Murmur” continued on page 3 “Big Hiss” continued on page 4 3 QUASARS: Express T r ains to Netherworlds

stronomers have found tone as the train moves away a quasar contains. a quasar racing towards from us quickly. The quasar, like Athe edge of the known a high speed train, was mov­ But the message might be from universe at 450 million miles an ing away from us very quickly. the universe itself. Astronomers hour. That speed is two-thirds However, with quasar 3C 273, are looking for more quasars the speed of light! This and this “red-shift” showed more and measuring their distance other newly discovered quasars than just speed. Its speed was from us. Using the 200-inch aren’t just fast—they are really 16 percent of the speed of light. Mount Palomar telescope, they bright, too. Because they are That is more than 100 million want to see some of these qua­ visible to us Earthlings means miles per hour! sars whose light is from 15 bil­ that they have to be extremely lion years ago, which is how long bright. The speed of quasars The speed record holder is qua­ it would take their light to reach and their brightness makes sar BSO-1. Marteen Schmidt us if they are moving to the edge them very mysterious since no and Allan Sandage used the of the known universe. If the one really even knows what same technique for BSO-1 as light from 15 billion years ago is quasars are. they did for 3C 273. But, no one reaching earth now, it would be can even explain what BSO-1 is from the early universe.♦ Radio astronomers have seen yet. quasars for years. Five years ago astronomers matched one Sandage did say, though, that of these quasars, or quasi-stel­ quasars give astronomers hints lar objects, with an object seen about the size and shape of the with telescopes using visible universe. light instead of radio signals. But it wasn’t until two years ago that They know that quasars are astronomers Jesse Greenstein probably NOT coded messages and Maarten Schmidt were able from a super-civilization. Rus­ to see quasar 3C 273’s colors. sian astronomer Nikolai Karda­ shev suggested that early theo­ The visible spectrum shows ry. US astronomers say that is astronomers what elements probably not true. Any civiliza­

the light-giving object contains. tion that could send something Bachall et al., ApJ 450, 486 (1995) They found amazing things in that bright and that fast would this quasar. The color spectrum have to send the messages with shifted towards the red end of the power of 10,000 billion suns. Image Credit: the spectrum. This was kind of That power—10,000 billion like a train’s whistle dropping in suns—is the amount of energy Quasar 3C 273

“Murmur” continued from page 2 State Theory. will break into its basic building blocks, then explode again in an­ Steady State Theory of the Uni­ The Big Bang Theory implies other big bang. We will have an­ verse. The Steady State Theory, two different fates for the uni­ other new universe. The closed which many astronomers have verse. Dicke and his team say universe idea is similar to the favored over the Big Bang The­ that either the universe will Steady State Theory because ory, says that the universe is ex­ expand and cool forever, an neither one has a beginning or panding because new particles “open universe,” or the universe an end. The Big Bang Theory are spontaneously created in is a “closed universe.” If it is a has no way of figuring out what empty space. But because this closed universe, the gravity of all existed before the last big bang theory has no explanation for of the matter in the universe will and no way of stopping us from cosmic background radiation, pull back together and collapse being crushed into another hot the discovery weakens Steady into another hot ball. All matter ball before the next big bang.♦ 4 Supernovae Leave Behind Cosmic X-Ray Generators

wo years ago, astronomers tion as another past supernova. If doesn’t put out a lot of X-rays, we discovered that the universe you drew a map of all X-ray sourc­ can easily detect those because Tis full of X-rays. Now they es, then compared it to another it’s the closest source in our sky. are starting to find very small map of supernova remnants, the So the first research rocket launch sources even more accurately. two maps would look almost the in 1962 was designed to use its And the machines they are using same. Astronomers don’t know five minutes to look at the Moon. look nothing like the machines in why there is X-ray radiation from Riccardo Giacconi and his team your doctor’s office! these sources that are far, far at the American Science and En­ away from the Sun (where we get gineering Group expected to dis­ One X-ray source astronomers many X-rays from). But if Ophiu­ cover Moon minerals fluorescing, found is the Crab Nebula — it is chus XR-1 really does come from or giving off light, after they were the remains of a star that explod­ a supernova remnant, as astrono­ hit with heavy particles (known as ed almost 900 years ago. The mers predict, then they can com­ “solar wind”) from the Sun. But remains of a star are often called pare the two X-ray sources to try they were wrong. a supernova remnant. Another to answer some questions. X-ray source, Ophiuchus XR-1, Instead, astronomers found seems to be in the same direc- Locating these two X-ray sources something even more unexpect­ was not easy. X-rays cannot get ed and amazing. They found X- through the Earth’s atmosphere. rays coming from every direction. The trick was to get X-ray instru­ They found an especially intense ments enough time in space, on X-ray source coming from the di­ rockets, to allow them to find the rection of the constellation Scor­ distant sources. Because of this, pius. They named this area Sco X-ray astronomy is difficult and ex­ X-1. This source is different from pensive. Each rocket launch only the Crab Nebula, where the X- allows five minutes of time to ob­ ray source seems to come from serve. This difficulty is not all bad, objects. Sco X-1 has not been however; because the Earth’s tracked to any known object. At atmosphere blocks X-rays, life is this point, it is a space mystery. protected from these deadly rays

NASA that sometimes flare from the Sun. Someday astronomers hope they can place one of their instruments Because each rocket flight only in a stable orbit above the earth gives X-ray astronomers five min­ so they can spend even more Image Credit: utes of study, the discoveries of the time looking at the X-ray universe. A rocket launches from Wallops Island X-ray sources at the Crab Nebula Until then, they will be limited to in Virginia. This rocket is similar to and Ophiuchus XR-1 took three observing X-rays in five minute ones used to find X-ray sources such years of research. During that periods while their instruments as Scorpius X-1 and, more recently, the time, astronomers were looking are strapped to a rocket. ♦ Crab Nebula and Ophiuchus XR-1. for other X-ray sources besides our Sun. Even though our Sun

“Big Hiss” continued from page 2 most made the discovery. He omers didn’t connect the theory Two other astronomers just reported measuring background with their discoveries. It just didn’t missed the radiation as well. Ten temperature of 4 degrees Kelvin, make sense to them. Penzias and years ago, at the Nançay Radio plus or minus 3 degrees. Wilson might have had the same Observatory, Emile Le Roux re­ problem if the Princeton Universi­ ported microwave background ra­ Neither Le Roux nor Shmaonov ty team, just down the street from diation of 3 degrees Kelvin, plus connected their observations to them, did not see the background or minus 2 degrees. Then in 1957 the predictions of the Big Bang radiation as the same radiation it was Tigran Shmaonov who al­ Theory. The predictions existed predicted by the Big Bang Theo- as early as 1948, but the astron­ r y.♦ 5 Galaxies Still Misbehaving alaxies are not heavy how fast stars are orbiting in enough. That’s what galaxies by using stopwatches Gastronomers are saying. or telescopes because the When astronomers compare movements are too small for the amount of light coming from that. Instead, they look at small galaxies with how much they areas of starlight in the galaxy,

“weigh,” the numbers don’t work then break the starlight down Sandage & Bedke 1994, Carnegie out right. Even the latest “weigh­ into the color spectrum (much in” does not match. Spiral galaxy like astronomers do when

NGC 3521 has the mass, or studying quasars). This rainbow Image Credit: Atlas of Galaxies “weight,” of 80 billion suns. And of colors that make up starlight Sprial galaxy NGC 3521; inset is spiral galaxy NGC 972 has a contain lines of color that shift galaxy NGC 972. mass of 12 billion suns. But there based on how fast the stars are is more light coming from the moving. The speed can then be they studied was much closer— galaxies than that. They should used to determine the mass of NGC 972 had a 1.2 ratio. Teams “weigh” more. And astronomers the galaxy they are a part of. of researchers led by Margaret don’t know why they don’t. Burbridge at the University of To compare numbers of mass California at San Diego reported To measure the amount of and amount of light in a galaxy, these results in recent issues of starlight coming from the two astronomers come up with a the Astrophysical Journal. galaxies, astronomers carefully “mass-to-light ratio.” This is measured their total brightness, based on the mass and light These two galaxies are not or luminosity. They record these (luminosity) of our own Sun, unique. Other researchers are on photographic plates. They since we know the mass and the also finding mismatched mass­ also look at how the stars in amount of light from our Sun. to-light ratios. No one has a each galaxy spread out from the Our Sun’s mass-to-light ratio good explanation for this. center to the edges. The way is one. The mass is “one solar the stars spread out is different mass” and the luminosity is “one But astronomers today are for every galaxy. solar luminosity.” A one-to-one doing better than astronomers ratio is equal to one. If another in 1933. Fritz Zwicky at CalTech They measure the mass of galaxy or object has a ratio more measured the amount of light the galaxy using the same than one, then that implies it from the entire Coma cluster of technique they used long ago to has more mass than light, which galaxies (instead of small light figure out the mass of the Sun. If means it “weighs” more than it samples like they did with NGC you have a small-massed object should. 3521 and NGC 972). Then he (small compared to the Sun or measured the speeds of the larger object!) orbiting the large- The NGC 3521 galaxy was galaxies as they orbited the massed object, and you know studied with the 82-inch telescope cluster. This gave him the mass. how fast the object is orbiting, at McDonald Observatory at the He came up with a mass-to-light then you can figure out the large University of Texas. When they ratio of about 500. That means object’s mass. You can use the studied the galaxy, they found a 99% of the matter is hidden, same technique for galaxies. mass-to-light ratio of 4 or more. or not giving off light! At the This time you use the stars that This means the galaxy weighs 4 moment, most astronomers just are orbiting the galaxy’s center. times more than it should, based ignore such extreme numbers on how much light it gives off. since they are probably just Astronomers can’t find out The mass of the other galaxy flukes. ♦