--%>
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 : Define Joule or SI unit of energy Joule

    Joule: J (after J.P. Joule, 1818-1889): The derived SI unit of energy stated as the quantity of work done by moving an object via a distance of 1 m by exerting a force of 1 N; it therefore has units of N m.

    		•
  • Q : Acceleration during this interval The

    The velocity of a body was observed to be constant throughout five minutes of its motion. Determine its acceleration during this interval?

    		•
  • Q : What are Woodward-Hoffmann rules

    Woodward-Hoffmann rules: The rules leading the formation of products throughout certain kinds of organic reactions.

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

    What do you mean by the term fusion reaction?

    		•
  • Q : What is Curie constant and Curies law

    What is Curie constant and Curies law? Curie constant: C (P. Curie): The characteristic constant, dependent on the material in question that points out the proportionality among its susceptibility

    		•
  • Q : Define Tesla or SI unit of the magnetic

    Tesla: T (after N. Tesla, 1870-1943): The derived SI unit of the magnetic flux density stated as the magnetic flux density of a magnetic flux of 1 Wb via an area of 1 m2; it therefore has units of Wb/m2.

    		•
  • Q : Explain Malus law Malus' law (E.L.

    Malus' law (E.L. Malus): The light intensity I of a ray with primary intensity I0 travelling via a polarizer at an angle theta among the polarization of the light ray and the polarization axis of the polarizer is specified by:

    Q : What is Avogadro constant Avogadro

    Avogadro constant: L; NA (Count A. Avogadro; 1811) The total number of items in a sample of a substance that is equivalent to the number of molecules or atoms in a sample of an ideal gas that is at customary temperature and pressure. It is equivalent

    		•
  • Q : Define Pseudoforce Pseudoforce : The

    Pseudoforce: The "force" that arises as an observer is plainly treating an accelerating frame as an inertial one.

    		•
  • Q : Define Luxon Luxon : The particle that

    Luxon: The particle that travels solely at c (that is the speed of light in vacuum). All luxons have a rest mass of exactly zero. Though they are mass less, luxons do take momentum. The photons are the prime illustration of luxons (that is the name it

    		•