Why in News?

• Dark matter is not made up of primordial black holes smaller than a tenth of a millimetre, say scientists who have put the theory put forward by the late Stephen hawking to its most rigorous test to date.

Dark matter:

• Dark matter is the hypothetical matter existing in space whose properties are unclear to scientists. The term ‘dark’ is used to mention the unknown. It only interacts by way of gravity and the weak atomic
• force. It does not interact through either the strong atomic force or electromagnetism, therefore, it cannot be seen and is hard to notice.

Background:

• Black holes are objects so dense that not even light can escape their gravity, and since nothing can travel faster than light, nothing can escape from inside a black hole. On the other hand, a black hole exerts the same force on something far away from it as any other object of the same mass would. For example, if our Sun was magically crushed until it was about 1 mile in size, it would become a black hole, but the Earth would remain in its same orbit.

Formation of black hole:

• After the death of star, it changes into one of these three forms according to its solar mass. White dwarf: stars below 1.4 solar mass lose their outer layer and their core cools down to form white dwarf. Later it changes into yellow dwarf and then to red dwarf. Finally, it becomes invisible by forming black dwarf which neither emits electric fields nor heat energy. Neutron star: the core of the star finishes up as Neutron start if the mass is greater than 1.4 but less than 5 solar mass
• Black hole: if the original mad of the star is greater than 5 solar mass the core does into black hole which is exactly not a hole but a curvature caused due to a high-density object.

Could a Black Hole Destroy Earth?

• Black holes do not go around in space eating stars, moons and planets. Earth will not fall into a black hole because no black hole is close enough to the solar system for Earth to do that.
• Even if a black hole the same mass as the sun were to take the place of the sun, Earth still would not fall in. The black hole would have the same gravity as the sun. Earth and the other planets would orbit the black hole as they orbit the sun now. The sun
• will never turn into a black hole. The sun is not a big enough star to make a black hole.