--%>
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 : Secondary electron image and back

    What is main difference between secondary electron image and the back scattered electron image? State briefly.

    		•
  • Q : Define Tau-theta paradox Tau-theta

    Tau-theta paradox (1950s): Whenever two distinct kinds of kaons, tau and theta (nowadays tau refers to a totally different particle) decay, tau decays into three particles, whereas the theta decays into two. The tau and theta vary onl

    		•
  • Q : Explain Ohms law Ohm's law (G. Ohm;

    Ohm's law (G. Ohm; 1827): The ratio of the potential difference among the ends of a conductor to the current flowing via it is constant; the constant of proportionality is termed as the resistance, and is distinct for different materials.

    		•
  • Q : Difference between the electron and a

    Write down the vital difference between the electron and a beta ray?

    		•
  • Q : How radiation emitted from the body

    Describe the procedure how radiation emitted from the body? Illustrate in brief.

    		•
  • Q : Explain Bohr magneton and Bohr radius

    Bohr magneton (N. Bohr) - This is the quantum of magnetic moment. Bohr radius (N. Bohr) - The distance equivalent to the mean distance of an electron from the nucleus in the ground state of hydroge

    		•
  • Q : Black-hole dynamic laws or laws of

    Explain  laws of black-hole dynamics or First law of black hole dynamics and Second law of black hole dynamics? 

    Q : Define Permittivity of free space or

    Permittivity of free space: electric constant; epsilon_0: The ratio of the electric displacement to the intensity of the electric field generating it in vacuum. It is equivalent to 8.854 x 10-12 F/m.

    		•
  • Q : Define Kirkwood gaps Kirkwood gaps

    Kirkwood gaps (Kirkwood): The gaps in the asteroid belt, caused by the resonance effects from Jupiter. Similar gaps are also exists in Saturn's rings, due to the resonance effects of the shepherd moons.

    		•
  • Q : What do you mean by the term positron

    What do you mean by the term positron? Explain in short.

    		•