A far-out discovery
A T-shirt pinned to the wall of Arjun Dey's office capsulizes his recent life: "I found the most distant galaxy in the universe, and all I got for it was this lousy T-shirt."
To be truthful, that's not all Dey got for his accomplishment. The Hopkins postdoctoral fellow and his colleagues also get to report to the astronomical world (in Astrophysical Journal Letters) that they had surpassed an astronomical milestone, the 5.0 redshift mark. Redshift is an indication of an object's distance from Earth. In astronomy,their accom-plishment is comparable to breaking track's three-minute mile.
The galaxy they spotted has a red shift of 5.34. The next most distant galaxy ever detected has a redshift of 4.92.
Since the most distant objects are also the oldest, the researchers were, in effect, peering farther back in time than astronomers have ever done before, to a time when the universe was only about 800 million years old, or 6 percent of its current age.
"The exciting thing is that nothing is known about this phase of the universe," says Dey. "It's like saying, `If you see one animal in the forest, what else might you see?'"
The astronomers suspect that their object is a galaxy in its
earliest developmental stage. Embryonic galaxies such as these,
says Dey, "eventually turn into something like the one we live
in, and are undergoing their first episode of star formation.
They are essentially collapsing from a large gas cloud and
forming their first generation of stars." By studying this museum
of ancient cosmological history, astronomers will be able to
trace galaxy evolution.
The astronomers spotted and examined the galaxy using the world's largest telescopes, Keck I and II, which sit atop a dormant volcano in Mauna Kea, Hawaii. In September 1997, the team was using one of the telescope's spectrographs to analyze the light from galaxies that appeared to be candidates for having redshifts greater than 4.0. Right next to one of their candidate galaxies, they saw a spectral signature that looked like it came from another high redshift object. In December, they went back for a closer look.
"We found this galaxy entirely by accident," notes Dey. His collaborators were Hyron Spinrad, Daniel Stern, and James Graham, at the University of California at Berkeley; and Frederic Chaffee, of the W.M. Keck Observatory, in Kamuela, Hawaii.
Light travels at a speed of approximately 186,000 miles per second. That is a constant. But the universe is expanding, and the farther away an object is from Earth, the faster the object is receding. As a galaxy moves away, its light waves get stretched out. The farther a galaxy is, the faster it is moving away, and the more its light waves get stretched, or "shifted," toward the red end of the spectrum. Redshift, then, is proportional to an object's distance from Earth.
The light reaching the Keck Telescope now was emitted by this most distant galaxy 12 billion years ago.
The galaxy is in the constellation Triangulum, in the Northern Hemisphere. It appears to be smaller than the Milky Way, says Dey. The scientists plan to request time on the Hubble Space Telescope for further observations.
Finding the highest redshift galaxy, "is pretty exciting, but I'm sure the record will be broken in a matter of months, maybe weeks," says Dey, who decided he wanted to become an astronomer at age eight, when he joined an amateur astronomer's club in his native Bangalore, India, and began grinding telescope lenses.
A new generation of powerful ground-based telescopes, including the Keck, "have dramatically revolutionized our understanding of high redshift objects," says Dey. A dozen similar strong telescopes will be built in the next 10 years. --MH
Hopkins research professor Michael Karweit is giving freshmen a way to get hands-on engineering experience. Well, sort of.
Karweit has developed a virtual laboratory that allows students to tackle the type of engineering projects they would encounter in the working world.
Take the spaghetti bridge. Through simulation in the virtual lab, a student can design a bridge and test its weight- bearing properties by clicking the computer mouse on various bridge stress points. At the end, a student builds a real model of the bridge out of uncooked spaghetti. Karweit then tests it to see if it can hold weight. Other projects are more high-tech, such as designing a robotic arm--a costly project to conduct in a real world lab. Karweit's students create and test a virtual two-segment arm, programming its rotational movements.
"Students can do something and if it turns out wrong, they can try this, or this, or this, just as they would in a laboratory," says Karweit, a research professor in the Department of Chemical Engineering.
He's found that students who major in engineering often get bogged down in physics and math courses before they get to the engineering projects. They may bail out of the major early, or find out too late that engineering doesn't interest them. The introductory course, he hopes, will give freshmen a chance to test their affinity for the field, quickly and easily.
Titled What Is Engineering? his course uses the new computer programming language, Java. Anyone with a major Web browser such as Netscape's Navigator, and a 32-bit operating system such as Windows 95, can conduct experiments. The simulated science lab is free and open to the public ( www.jhu.edu/~virtlab).
Karweit recently received a $258,000 grant from General Electric to expand his computer course offerings. His program could be used by other colleges and advanced high school classes. --JPC
Sniffing out sex appeal
What makes a woman's heart flutter when she's with a certain special man? His physique? Yes. His sexy smile? Sure. But there is also that inexplicable electric spark. Could this certain je ne sais quoi be... his immune system?
If rodents are any indication, it could be, says Hopkins psychology graduate student Sabra Klein. In her studies with behavioral psychologist Randy Nelson, Klein finds that females of certain rodent species sniff out, literally, males with the most robust immune systems.
Klein began studying the interplay between immunity and mating behavior after reading studies that show males generally have lower immunity than females. The difference appears to hold across species. Men are more susceptible to a variety of infections, such as dysentery, gonorrhea, and malaria; and to certain cancers, says Klein. (Conversely, females are at greater risk of illnesses caused by an overactive immune system, such as systemic lupus erythematosus.)
Studies also suggested that testosterone plays a role in reduced immunity. Researchers found, for instance, that castrated reindeer are less susceptible to infection with warble flies than are uncastrated male reindeer.
Klein has continued in this line of research using meadow voles-- dark gray, hamster-size rodents.
Working with Nelson, Klein infected male voles with a non-contagious parasite. She then allowed female voles to choose between spending time in soiled bedding that had been used by an infected male vole or an uninfected one. The female voles opted for the bedding of the uninfected males.
"The results suggest that information about infection status is carried in the urine," says Klein. The urine may contain pheromones, volatile chemical cues that convey information from one animal to the next. "In rodents, olfactory cues are very important," she notes.
In an interesting twist to this experiment, the scientists injected male meadow voles with an innocuous protein that causes the vole's immune system to make antibodies but does not make the animals ill. Again, they gave females a choice between bedding previously used by either infected or uninfected males. The female voles still opted for the bedding used by uninfected males.
"A female wants a mate that is not prone to infection," Klein hypothesizes. "By choosing an uninfected male, she may choose a mate that has good genes for resistance. She will then pass on those genes to her offspring. She herself is also less likely to contract an illness. Also, by mating with an uninfected male, she gains a mate who may provide more resources for her and her offspring."
Initial research suggests that people, like voles, can also detect "vibes" about a companion's immunity, say Nelson and Klein. A recent Swiss study, for example, suggests that people subconsciously perceive information about the genetics of a person's immune system through that person's body odor. Here too, says Klein, pheromones may be the silent, invisible communicator. --MH
Hopkins senior Vivek Baluja thought that establishing a community computer center would be a worthy cause. How to bring it about? How else? Via a barrage of e-mail messages to the household of Bill Gates, uber-rich founder of Microsoft.
"I didn't think there'd be any other way to reach Gates other than e-mail," says Baluja. "I asked around and got his wife's e-mail address and sent her e-mail for two to three months, about 40 or 50 times a week. Her reaction was: `I'm impressed by your persistence, but you don't need to e-mail me this much,'" Baluja recalls, "so she referred me to the Gates Foundation and said she would talk to Mr. Gates."
Baluja, a computer science major, convinced Gates to donate $40,000, plus $60,000 in Microsoft software, to the Greenmount Recreation Center near Homewood. Area residents can now take classes on 18 new computers. Additional contributions came from the Abell Foundation and other community groups. Says Edward Banks, the center's director, "We've got the best computer lab in Baltimore City." --JPC
Written by Joanne P. Cavanaugh and Melissa Hendricks.
RETURN TO APRIL 1998 TABLE OF CONTENTS.