--%>
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 Siemens or SI unit of an

    Siemens: S (after E.W. von Siemens, 1816-1892): The derived SI unit of an electrical conductance equivalent to the conductance of an element which has a resistance of 1 O [ohm]; this has units of O-1.

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

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

    		•
  • Q : Define Ergosphere Ergosphere: The area

    Ergosphere: The area around a rotating black hole, among the event horizon and the static limit, where the rotational energy can be removed from the black hole.

    		•
  • Q : What is Beauty criterion Beauty

    Beauty criterion (Dirac) - The idea that more aesthetically pleasing a theory is the superior it is. In nature this criterion does not stand up to the actual test -- whether or not forecasts of a given theory agree with observational tests -- however

    		•
  • Q : What is neutral buoyancy What do you

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

    		•
  • Q : Define Noether theorem Noether theorem

    Noether theorem (Noether): A theorem that explains that symmetries are what gives rise to conserved quantities. For example, the translational symmetry (that is the fact that the laws of physics work the same in all positions) gives r

    		•
  • Q : Define Watt or SI unit of power Watt: W

    Watt: W (after J. Watt, 1736-1819): The derived SI unit of power, stated as a power of 1 J acting over the period of 1 s; it therefore has the units of J/s.

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

    What do you mean by the term geocentric? Briefly describe it.

    		•
  • 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 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.

    		•