--%>
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 Michelson-Morley experiment

    Michelson-Morley experiment (A.A. Michelson, E.W. Morley; 1887): Probably the most famous null-experiment of all time, designed to confirm the existence of the proposed "lumeniferous aether" via which light waves were considered to pr

    		•
  • 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 : Define Lenzs law Lenz's law (H.F. Lenz;

    Lenz's law (H.F. Lenz; 1835): The induced electric current always flows in such a direction that it resists the change generating it.

    		•
  • Q : Define Pascal or SI unit of pressure

    Pascal: Pa The derived SI unit of pressure stated as 1 N acting over a region of 1 m2; it therefore has units of N/m2

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

    What do you mean by the term crest? Briefly illustrate it.

    		•
  • Q : What is Dulong-Petit law Dulong-Petit

    Dulong-Petit law (P. Dulong, A.T. Petit; 1819): The molar heat capacity is around equivalent to the three times the ideal gas constant: C = 3 R

    		•
  • Q : Explain Curie-Weiss law Curie-Weiss law

    Curie-Weiss law (P. Curie, P.-E. Weiss): A more broad form of Curie's law that states that the susceptibility, khi, of a paramagnetic substance is associated to its thermodynamic temperature T by the equation:

    Q : Negative mass defect State is it

    State is it possible that the nucleus consists of negative mass defect?

    		•
  • Q : Define Olbers paradox Olbers' paradox

    Olbers' paradox (H. Olbers; 1826): If the Universe is infinite, consistent, and unchanging then the whole sky at night would be bright -- concerning as bright as the Sun. The further you stared out into space, the more stars there would be, and theref

    		•
  • Q : Define neuro-modulators What do you

    What do you mean by the term neuro-modulators? Briefly define it.

    		•