Dark Matter & Dark Energy
The Mystery of Dark Matter
Dark matter is an invisible substance that makes up approximately 27% of the universe. Despite being five times more abundant than ordinary matter, it doesn't emit, absorb, or reflect light, making it completely invisible to telescopes. We only know it exists because of its gravitational effects on visible matter.
The evidence for dark matter comes from observations of galaxy rotation curves, gravitational lensing, and the cosmic microwave background. Galaxies rotate so fast that they should fly apart, but something invisible is holding them together. This "something" is dark matter, forming a halo around galaxies that provides the necessary gravitational glue.
Dark Energy: The Cosmic Accelerator
Dark energy is an even more mysterious force, making up about 68% of the universe. Discovered in 1998 through observations of distant supernovae, dark energy is causing the universe's expansion to accelerate rather than slow down, as scientists previously expected.
This discovery was so surprising that it earned the Nobel Prize in Physics in 2011. Dark energy appears to be a property of space itself, pushing galaxies apart at an ever-increasing rate. If this acceleration continues, the universe may end in a "Big Rip," where even atoms are torn apart by the expansion of space.
The Search for Answers
Scientists are using multiple approaches to detect dark matter particles. Underground detectors search for Weakly Interacting Massive Particles (WIMPs), while particle accelerators like the Large Hadron Collider attempt to create dark matter in the laboratory. Space-based telescopes map the distribution of dark matter through gravitational lensing.
Understanding dark matter and dark energy is crucial for cosmology. These invisible components determine the universe's fate and structure. Current research suggests dark matter might consist of axions, sterile neutrinos, or other exotic particles. The nature of dark energy remains one of physics' greatest unsolved mysteries, with theories ranging from a cosmological constant to modifications of general relativity.
