Category Archives: universe

Sound of the universe

Cosmic noise characteristics are similar to those of thermal noise. Cosmic noise is experienced at frequencies above about 15 MHz when highly directional antennas are pointed toward the sun or to certain other regions of the sky such as the center of the Milky Way Galaxy. Celestial objects like Quasars, super dense objects that lie far from Earth, emit electromagnetic waves in its full spectrum including radio waves. We can also hear the fall of a meteorite in a radio receiver; the falling object burns from friction with the Earth’s atmosphere, ionizing surrounding gases and producing radio waves. Cosmic Microwave Background Radiation (CMBR) from outer space, discovered by Arno Penzias and Robert Wilson, who later won the Nobel Prize for this discovery, is also a form of cosmic noise. CMBR is thought to be a relic of the Big Bang, and pervades the space almost homogeneously over the entire celestial sphere. The bandwidth of the CMBR is wide, though the peak is in the microwave range.

Sounds from different nebulae.

Sounds from different comets

Sounds of the Sun

Sounds of the Eskimo nebula NGC2392.

Sounds of a quasar

A homogeneous universe

Why is the universe homogeneous?

In the standard Big Bang theory, when we go back in time, the current distance between any two points in space would decrease significantly. The current light signals between these two would also take a much shorter amount of time to approach the other. This case can be explained based on the gravitational force. If it was a sucking force, the universe expanding rate would theoretically decrease. The opposite however had occurred during the inflationary phase, the gravitational force was a pushing force which increased the expanding rate of the universe exponentially. This phase is described mathematically by a particular equation named Hartle-Hawking.

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