--%>
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 : Explain avogadro's hypothesis

    Avogadro's hypothesis (Count A. Avogadro; 1811): Equivalent volumes of all gases at similar temperature and pressure contain equivalent numbers of molecules. This is, in fact, true only for the ideal gases.  <

    		•
  • Q : Explain Right-hand rule Right-hand

    Right-hand rule: The trick for right-handed coordinate systems to establish which way the cross product of two three-vectors will be directed. There are some forms of this rule, and it can be exerted in many manners. If u and v are two vectors that ar

    		•
  • 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 : Candela Candela : The basic SI unit of

    Candela: The basic SI unit of luminous intensity stated as the luminous intensity in a given direction of a source which emits monochromatic photons of frequency 540 x 1012 Hz and encompasses a radiant intensity in the direction of 1/683 W/

    		•
  • 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 : Define Zeeman Effect or Zeeman line

    Zeeman Effect: Zeeman line splitting (P. Zeeman; 1896): Zeeman Effect is the splitting of lines in a spectrum whenever the source is exposed to the magnetic field.

    		•
  • Q : Semiconductors and magnetism I need

    I need well-explained answers on the questions in attached documents

    		•
  • Q : What is Cherenkov radiation Cherenkov

    Cherenkov radiation (P.A. Cherenkov): The radiation emitted by a huge particle which is moving faster than light in the medium via which it is travelling. No particle can travel faster than the light in vacuum, however the speed of light in other medi

    		•
  • Q : How elevation and air pressure affects

    Briefly state how does the elevation and air pressure affects the boiling point of water?

    		•
  • Q : Rest mass energy of the electron What

    What do you mean by the rest mass energy of the electron?

    		•