At particle colliders just like the Giant Hadron Collider, researchers faucet into Einstein’s equations within the seek for dark matter particles. Credit score: Daniel Turbasa/Dreamstime.com
Does E = mc2 maintain true for dark matter and darkish power?
Gary George
Cincinnati, Ohio
Sure — briefly, that is true for all types of matter and power, together with dark matter and darkish power. However there are some essential particulars to think about.
E = mc2 is a particular case of the total equation E2 = (mc2)2 + (computer)2. The time period computer represents the kinetic power of an object, which implies the acquainted E = mc2 is barely precisely true for objects at relaxation or in the identical relaxation body, the place the momentum p is zero. That’s why the mass (m) within the equation can be known as relaxation mass.
Normally, the a part of the equation containing the remaining mass is way bigger than the kinetic power. Then E = mc2 is an effective approximation for every little thing that doesn’t transfer at a big fraction of the pace of sunshine. And talking of sunshine, photons (the particles of sunshine and electromagnetism) are the opposite excessive of the total equation. They don’t have any relaxation mass (in order that time period turns into zero) however they nonetheless have momentum and thus power.
The truth that kinetic power can be a part of the total power of particles is exploited by scientists at particle accelerators, just like the Giant Hadron Collider at CERN. By accelerating particles to just about light-speed, new particles may be created in head-on collisions which have much more relaxation mass than the unique ones. Researchers use this technique to seek for dark matter particles by attempting to create dark matter from the mass and power of different particles.
The equation even holds true for darkish power. The only method to perceive darkish power is because the power held by the vacuum of space itself. So, even in probably the most excellent vacuum with out a single particle of matter, there’s some tiny quantity of power. For instance, the darkish power content material for a sphere enclosed by the Moon’s orbit would solely equate to a mass of about 3 kilos (1.4 kilograms), which is definitely overshadowed by just about every little thing else inside that quantity. Nonetheless, because the universe is generally plenty of empty space, this tiny quantity of power held by the vacuum of space quantities to the vast majority of the total power content material within the universe. Because of the odd properties of darkish power, the gravitational pull generated by its mass equal is definitely overcome by its detrimental strain, which is the drive driving the accelerated growth of the universe.
Christoph Saulder
Cosmologist, Korea Astronomy and House Science Institute, Daejeon, South Korea
