--%>
Assignment Help - homework help

Explain Drake equation

Drake equation (F. Drake; 1961): The method of estimating the number of intelligent, scientific species (that is, able to communicate with other species) in subsistence in our space.

N = R fp ne fl fi ft L.

Here,

N is the number of species explained above at any specified moment in our Galaxy. The parameters it is evaluated from are as follows:

R = the rate of star formation in our solar system (in stars per year);
fp = the fraction of stars that contain planets;
ne = the total number of habitable planets per system with planets;
fl = the fraction of habitable planets on which the life arises;
fi = the fraction of such planets on which the life develops intelligence;
ft = the fraction of such planets where the intelligence grows into a technological civilization which is capable of communication; and
L = the mean life-time of such a scientific civilization.

Out of these quantities, only the first -- R -- is recognized with anything like any reliability; this is on the order of 10 stars per year. The others, most particularly the fractions, are approximately totally pure speculation at this point. Computations made by respectable astronomers vary by something like ten orders of magnitude in the last estimation of the number of species out there.

   Related Questions in Physics

  • Q : Biot-Savart law Biot-Savart law (J.B.

    Biot-Savart law (J.B. Biot, F. Savart) - The law which explains the contributions to the magnetic field by an electric current. This is analogous to the Coulomb's law. Mathematically: dB = (mu0 I)/(4 pi r2) dl cross e

    		•
  • Q : What is Kirchhoffs law of radiation

    Kirchhoff's law of radiation (G.R. Kirchhoff): The emissivity of a body is equivalent to its absorbptance at similar temperature.

    		•
  • Q : Describe Wiedemann-Franz law

    Wiedemann-Franz law: It is the ratio of the thermal conductivity of any pure metal (substance) to its electrical conductivity is just about constant for any specified temperature. This law holds pretty well apart from at low temperatures.

    		•
  • Q : Why the length of a standard meter

    Describe the reason in short why the length of a standard meter re-defined in the year of 1983?

    		•
  • Q : Explain Kirchhoffs laws or Kirchhoffs

    Kirchhoff's laws (G.R. Kirchhoff) Kirchhoff's first laws: An incandescent solid or gas in high pressure will generate a continuous spectrum.

    Q : Define Ehrenfest paradox Ehrenfest

    Ehrenfest paradox (Ehernfest, 1909): The special relativistic "paradox" including a fast rotating disc. As any radial segment of the disc is perpendicular to the direction of motion, there must be no length contraction of the radius;

    		•
  • Q : Why heat causes matter to expand What

    What is the reason that heat causes matter to expand? Briefly explain it.

    		•
  • Q : Explain Event horizon Event horizon:

    Event horizon: The radius which a spherical mass should be compressed to in order to convert it into a black hole, or the radius at which the time and space switch responsibilities. Once within the event horizon, it is basically impossible to escape t

    		•
  • Q : What is Hubble constant Hubble constant

    Hubble constant: H0 (E.P. Hubble; 1925): The constant that determines the relationship among the distance to a galaxy and its velocity of recession due to the growth of the Universe. As the Universe is self-gravitating, it is not trut

    		•
  • Q : What is Permeability of free space or

    Permeability of free space: magnetic constant: mu_0: The ratio of the magnetic flux density in the substance to the external field strength for vacuum. It is equivalent to 4 pi x 10-7 H/m.

    		•