--%>
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 Planck radiation law Planck

    Planck radiation law: The law which explained blackbody radiation better than its precursor, therefore resolving the ultraviolet catastrophe. This is based on the supposition that electromagnetic radiation is quantized.

    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 : Define Stefan-Boltzmann constant

    Stefan-Boltzmann constant: sigma (Stefan, L. Boltzmann): The constant of proportionality exist in the Stefan-Boltzmann law. It is equivalent to 5.6697 x 10-8 W/m2/K4.

    		•
  • Q : Define Machs principle Mach's principle

    Mach's principle (E. Mach; c. 1870): The inertia of any specific particle or particles of matter is attributable to the interaction among that piece of matter and the rest of the world. Therefore, a body in isolation would contain no inertia.

    		•
  • Q : What is Causality principle Causality

    Causality principle: The principle which cause must always precede effect. More properly, when an event A ("the cause") somehow persuades an event B ("the effect") that take

    		•
  • Q : Define Ohm or SI unit of electric

    Ohm: Omega: O (after G. Ohm, 1787-1854) The derived SI unit of electric resistance, stated as the resistance among two points on a conductor whenever a constant potential difference of 1 V generates a current of 1 A in the conductor;

    		•
  • Q : Define Tipler machine Tipler machine:

    Tipler machine: The solution to Einstein's equations of general relativity which permits time travel. A tremendously dense (that is, on the order of the density of neutron star matter), infinitely-long cylinder that rotates very quickly can form close

    		•
  • Q : Define Kelvin or basic SI unit of

    Define Kelvin or basic SI unit of thermodynamic temperature: Kelvin: K (after Lord Kelvin, 1824-1907): The basic SI unit of thermodynamic temperature stated as 1/273.16 of the thermodynamic temperature of triple point of the water.

    		•
  • Q : How elevation and air pressure affects

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

    		•
  • 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.

    		•