--%>
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 Hoop conjecture Hoop conjecture

    Hoop conjecture (K.S. Thorne, 1972): The conjecture (as so far unproven, although there is substantial proof to support it) that a non-spherical object, non-spherically compressed, will only form a black hole whenever all parts of the

    		•
  • Q : Explain Casimir effect Casimir effect

    Casimir effect (Casimir): The quantum mechanical effect, where two very big plates positioned close to each other will experience an attractive force, in the nonattendance of other forces. The cause is implicit particle-antiparticle p

    		•
  • Q : Report on Radiobiology for Travel Space

    I have a problem in wirting a report on Radiobiology for Travel Space.  Can someone provide me a complete report on the above topic.

    		•
  • 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 : Define Uniformity principle Uniformity

    Uniformity principle (E.P. Hubble): The principle which the laws of physics here and now are not dissimilar, at least qualitatively, from the laws of physics in preceding or future epochs of time, or somewhere else in the Universe. This principle was

    		•
  • Q : What is Universal age paradox Universal

    Universal age paradox: The two most straightforward techniques of computing the age of the Universe -- via red-shift measurements, and via stellar evolution -- outcome incompatible outcomes. Recent (in mid 1990s) measurements of the distances of far-a

    		•
  • Q : What is Negative feedback principle

    Negative feedback principle: It is the idea that in a system where there are self-propagating situations, those new situations tend to act against formerly existing situations. Such a principle is in actuality a restatement of the conservation law.

    		•
  • 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 : What is Magnetic monopole Magnetic

    Magnetic monopole: The hypothetical particle that comprises sources and sinks of the magnetic field. The magnetic monopoles have never been found, however would only cause pretty minor modifications to the Maxwell's equations. They also appear to be p

    		•
  • Q : Blackbody radiation What is Blackbody

    What is Blackbody radiation - The radiation - that is the radiance at specific frequencies all across the spectrum -- generated by a blackbody -- which is, a perfect radiator and absorber of the heat. Physicists had complexity exp

    		•