--%>
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 : What MeV in MeV photon signify What

    What does MeV in MeV photon signify? Briefly describe it.

    		•
  • Q : Define Hertz or SI unit of frequency

    Define Hertz or SI unit of frequency: Hertz: Hz (after H. Hertz, 1857-1894): The derived SI unit of frequency, stated as a frequency of 1 cycle per s; it therefore has units of s-1.

    		•
  • Q : Explain Joules laws and Joule's

    Joule's laws (J.P. Joule) Joule's first law: The heat Q generated whenever a current I flows via a resistance R for a specified time t is specified by: Q = I2

  • Q : Define Brackett series Brackett series

    Brackett series (Brackett) - The series (or sequence) that explains the emission spectrum of hydrogen whenever the electron is jumping to fourth orbital. All of the lines are in the infrared segment of the spectrum.

    		•
  • Q : What is Eotvos law of capillarity

    Eotvos law of capillarity (Baron L. von Eotvos; c. 1870): The surface tension gamma of a liquid is associated to its temperature T, the liquid's critical temperature, T*, and its density rho by: gamma ~=

    		•
  • Q : Define Singularity Singularity : The

    Singularity: The center of a black hole, where the curvature of space-time is maximal. At singularity, the gravitational tides deviate; no solid object can yet theoretically survive beating the singularity. Though singularities usually predict inconsi

    		•
  • Q : Explain Archimedes' principle What is 

    What is Archimedes' principle? A body which is submerged in a fluid is buoyed up by a force equivalent in magnitude to the weight of the fluid which is displaced, and directed upward all along a line via the c

    		•
  • Q : Define Pseudoforce Pseudoforce : The

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

    		•
  • Q : Calculating current in magnetically

    For the magnetically coupled circuit in Figure a, calculate I1 and I2. If the dotted terminals in are changed so that the circuit now becomes that in Figure b, re-calculate I1 and I2.

  • Q : Define Cosmological redshift

    Cosmological redshift: The effect where light emanates from a distant source appears redshifted since of the expansion of the space time itself.

    		•