--%>
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 Ehrenfest paradox Ehrenfest

    Ehrenfest paradox (Ehernfest, 1909): The special relativistic "paradox" including a fast rotating disc. As any radial segment of the disc is perpendicular to the direction of motion, there must be no length contraction of the radius;

    		•
  • Q : Calculate the concentration A

    A dual-wavelength spectrometer uses 780 nm and 830 nm. The molar extinction coefficients for oxy-hemoglobin (HbO2) and deoxy-hemoglobin (Hb) at these two wavelengths are: e_HbO2_780nm = 710 cm-1M-1, e_Hb_780nm = 1075 cm

    		•
  • Q : Explain Faradays law Faraday's law (M.

    Faraday's law (M. Faraday): The line integral of the electric field about a closed curve is proportional to the instant time rate of change of the magnetic flux via a surface bounded by that closed curve; in the differential form,

    		•
  • Q : Definition of Pascals principle Briefly

    Briefly state the definition of Pascal’s principle?

    		•
  • Q : What is Geometrized units Geometrized

    Geometrized units: The system of units whereby certain basic constants (G, c, k, and h) are set to unison. This makes computations in certain theories, like general relativity, much simpler to deal with, as such constants appear often.

    Q : Why heat causes matter to expand What

    What is the reason that heat causes matter to expand? Briefly explain it.

    		•
  • Q : Meaning of Network Define the meaning

    Define the meaning of Network in brief.

    		•
  • Q : Dielectric Materials Dielectric is a

    Dielectric is a material in which energy can be accumulated. Ideally, it  is  a non-conductor  of  electric  charge  like  insulators, but  an  efficient   supporter  of  electrostatic  fields. The

    		•
  • Q : Define Van der Waals force Van der

    Van der Waals force (J.D. van der Waals): The forces responsible for non-ideal behavior of gases, and for lattice energy of molecular crystals. There are three main causes: dipole-dipole interaction; dipole-induced dipole moments; and dispersion a for

    		•
  • Q : Explain Cosmological constant

    Cosmological constant (Lambda): The constant mentioned to the Einstein field equation, proposed to admit the static cosmological solutions. At the time the present philosophical view was steady-state model of the space, where the Universe has been aro

    		•