--%>
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 is Hooke law Hooke's law (R.

    Hooke's law (R. Hooke): The stress exerted to any solid is proportional to the strain it generates within the elastic limit for that solid. The constant of that proportionality is the Young modulus of elasticity for that material.

    		•
  • Q : What is Peltier effect Peltier effect

    Peltier effect (J.C.A. Peltier; 1834): The modification in temperature produced at a junction among the two dissimilar metals or semiconductors whenever an electric current passes through the junction.

    		•
  • Q : Define Mediocrity principle Mediocrity

    Mediocrity principle: The principle that there is nothing predominantly interesting about our position in space or time, or regarding ourselves. This principle most likely first made its real manifestation in the scientific community whenever Shapley

    		•
  • Q : Problem on multiplexed channels 4

    4 channels, two with a bit-rate of 200 kbps and two with a bit-rate of 150 Kbps are to be multiplexed employing multiple slots TDM with no sync bits. a. Find out the size of a frame in bits?

    Q : Define Machs principle Mach's principle

    Mach's principle (E. Mach; c. 1870): The inertia of any specific particle or particles of matter is attributable to the interaction among that piece of matter and the rest of the world. Therefore, a body in isolation would contain no inertia.

    		•
  • Q : Define Henry or SI unit of inductance

    Henry: H (after W. Henry, 1775-1836): The derived SI unit of inductance, stated as the inductance of a closed circuit in which the electromotive force of 1 V is generated whenever the electric current differs uniformly at a rate of 1

    		•
  • Q : Problem on beam For the beam

    For the beam illustrated below, we require to determine: (A) the support reactions

    		•
  • Q : What is Gaia hypothesis Gaia hypothesis

    Gaia hypothesis (J. Lovelock, 1969): The thought that the Earth as an entire must be regarded as a living organism and that biological procedures stabilize the atmosphere.

    		•
  • Q : Explain Right-hand rule Right-hand

    Right-hand rule: The trick for right-handed coordinate systems to establish which way the cross product of two three-vectors will be directed. There are some forms of this rule, and it can be exerted in many manners. If u and v are two vectors that ar

    		•
  • Q : Abhi what should be the choice of

    what should be the choice of standard unit.

    		•