Key Takeaways

  1. A strange energy beam in galaxy M87 appears to be moving almost five times faster than the speed of light, as measured by the Hubble Space Telescope.
  2. This phenomenon has been observed in many other galaxies as well, challenging our understanding of the laws of physics.
  3. The energy beam is actually a jet of plasma emanating from the central black hole of M87 and being ejected at velocities close to the speed of light.
  4. The illusion of faster-than-light movement is created by the changing position of the plasma blob over time and the shorter distance its light has to travel.
  5. Studying these jets provides valuable insights into the behavior of massive black holes and their impact on star formation in galaxies.

Please welcome to the stage a master illusionist. An energy beam that emerges from galaxy M87 like a toothpick in a cocktail olive is pulling off the ultimate magic trick: seemingly moving faster than the speed of light. This mind-boggling feat, observed by the Hubble Space Telescope, challenges our understanding of cosmic speed limits. In a backstage glimpse at the trick, we discover that the beam is a jet of plasma propelled by a central black hole, and its apparent superluminal motion is an optical illusion caused by its changing position and shorter light travel distance. This illusion not only captivates our imagination but also provides astronomers with insights into the fate of entire galaxies.

The phenomenon of the jet of plasma in M87 has been known since 1918, but its nature has become clearer with modern astronomical observations. The presence of a central black hole in galaxies, including M87, leads to the periodic inflow of stars and gas clouds. As the gas spirals towards the black hole, it heats up, and magnetic fields channel some of it into hot plasma jets. Although these jets can reach speeds near the speed of light, they do not surpass it.

To understand the illusion, imagine a glowing blob of plasma at the base of the jet emitting light, both moving towards Earth. Over a decade, the blob advances closer to us at a significant fraction of the speed of light. Consequently, the light emitted from the later position gains a head start on its journey towards Earth. When comparing the images captured from Earth, it appears as if the blob has simply shifted across the sky to the right. However, since the second position is also closer to us, its light has traveled a shorter distance, creating the illusion of faster-than-light motion.

The M87 jet is not merely an optical spectacle; it plays a crucial role in understanding the behavior of black holes and their impact on galaxies. Eileen Meyer of the University of Maryland, Baltimore County, explains that energy outflows from massive black holes can influence star formation in galaxies, but the mechanisms and energy content of these outflows remain uncertain. The superluminal appearance of the M87 jet allows astronomers to precisely measure its speed and power over a few years, which is extraordinary for distant objects like galaxies.

By studying M87, which is relatively close compared to other galaxies, researchers have made significant discoveries about the movement and structure of the plasma. Ongoing research over two decades is expected to reveal more surprises and deepen our understanding of these intriguing phenomena occurring millions of light years away.

In a universe where most celestial objects we witness moving across the sky are relatively close to us, the ability to observe the motion of objects like the M87 jet over a human lifetime is a truly astonishing feat. Despite her familiarity with the faster-than-light illusion, Eileen Meyer still finds wonder in the ability to witness distant objects in motion. The M87 jet not only challenges our perception of reality but also allows us to explore the mysteries of the cosmos in unprecedented ways.

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