A key feature of dynamos is that they need magnetic fields in order to work.īut out in the universe, there are no obvious wires or big steel structures, so how do the fields arise? Progress on this problem began about a century ago as scientists pondered the source of the Earth’s magnetic field. Through this process of induction, large generators or “dynamos” convert mechanical energy into the electromagnetic energy that powers our homes and offices. This is how the electricity that we use every day is produced. These fields, or voltages, can then drive electrical currents. When conductors, like copper wire, move in magnetic fields, electric fields are created. Scientists started thinking about this problem by considering the way that electric and magnetic fields were produced in the laboratory. Recent work has provided part of the answer, but many aspects of this question are still under debate.Īmplifying magnetic fields - the dynamo effect Since then, more powerful telescopes looking deep into space found that the fields were ubiquitous.Īnd while scientists had long learned how to make and use permanent magnets and electromagnets, which had all sorts of practical applications, the natural origins of magnetic fields in the universe remained a mystery. Magnetism on the sun was discovered at the beginning of the 20th century by its effects on the spectrum of light that the sun emitted. They were first observed on Earth thousands of years ago, through their interaction with magnetized minerals like lodestone, and used for navigation long before people had any understanding of their nature or origin. Naturally occurring magnetic fields are seen everywhere in the universe. New work carried out by MIT graduate student Muni Zhou, her advisor Nuno Loureiro, a professor of nuclear science and engineering at MIT, and colleagues at Princeton University and the University of Colorado at Boulder provides an answer that shows the basic processes that generate a field from a completely unmagnetized state to the point where it is strong enough for the dynamo mechanism to take over and amplify the field to the magnitudes that we observe. ![]() We wouldn’t have a complete and self-consistent answer to the origin of astrophysical magnetic fields until we understood how the seed fields arose. If a turbulent dynamo could only amplify an existing field, where did the “seed” magnetic field come from in the first place? But this remarkable discovery just pushed the mystery one step deeper. In previous research, scientists came to understand how turbulence, the churning motion common to fluids of all types, could amplify preexisting magnetic fields through the so-called dynamo process. Despite decades of intense interest and research, the origin of these cosmic magnetic fields remains one of the most profound mysteries in cosmology. These fields are weak - typically much weaker than those of a refrigerator magnet - but they are dynamically significant in the sense that they have profound effects on the dynamics of the universe. ![]() This is true not only in the neighborhood of stars and planets, but also in the deep space between galaxies and galactic clusters. When we look out into space, all of the astrophysical objects that we see are embedded in magnetic fields.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |