In the early 1960s the strange optical emission lines from starlike objects that also were producing trementdous radio signals confused scientists. finally, in 1963 maarten schmidt of the mount palomar observatory discovered that the optical spectra were just those of hydrogen, but redshifted because of the tremendous velocity of the object with respect to earth. the object was moving away from earth at a speed of 50,000 km/s! compare the wavelengths of the normal and redshifted spectral lines for the kα and kβ lines of the hydrogen atom.

Explanation:

k -alpha line corresponds to n = 2 to n = 1 transition

energy difference

= 13.6 - 13.6 / 4

= 10.2 eV

= 12375 / 10.2 A

= 1213 A

k -beta  line corresponds to n = 3 to n = 1 transition

energy difference

= 13.6 - 13.6 / 9

= 12.08  eV

= 12375 / 12.08 A

= 1024  A

For red shift the formula is

v / c = Δλ / λ

40000 x 10³ / 3 x 10⁸ =Δλ / λ

1 / 6 = Δλ / 1213

Δλ  = 1213/6

= 202.167 A

Wavelength of spectral line

= 1213 + 202.16

= 1415.16 A after red shift .

For k - beta line

1 / 6 = Δλ / 1024

Δλ = 1024 / 6

= 170.67 A

Wavelength of red shifted line

= 1024 + 170.67

= 1194.67 A

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me