--%>
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 Complementarity principle

    Complementarity principle (N. Bohr): The principle that a specified system can’t exhibit both wave-like behavior and particle-like behavior at similar time. That is, some experiments will reveal the wave-like nature of a system,

    		•
  • Q : What is Causality principle Causality

    Causality principle: The principle which cause must always precede effect. More properly, when an event A ("the cause") somehow persuades an event B ("the effect") that take

    		•
  • Q : Define Parsec Parsec : The unit of

    Parsec: The unit of distance stated as the distance pointed by an Earth-orbit parallax of 1 arcsec. It equals around 206 264 au, or about 3.086 x 1016 m

    		•
  • Q : What are Woodward-Hoffmann rules

    Woodward-Hoffmann rules: The rules leading the formation of products throughout certain kinds of organic reactions.

    		•
  • Q : Collision & Transition State Theory

    Assuming ideal gas: a)  Calculate the average velocity of a nitrogen molecule at 298K and compare to the velocity of a helium molecule at the same conditions. b)      Calculate the temperature wh

    		•
  • Q : Explain Thomson experiment or Kelvin

    Thomson experiment: Kelvin effect (Sir W. Thomson [later Lord Kelvin]): Whenever an electric current flows via a conductor whose ends are maintained at various temperatures, heat is discharged at a rate just about proportional to the

    		•
  • 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 : What is Arago spot What is  Arago

    What is Arago spot? The bright spot which appears in the shadow of a consistent disc being backlit by monochromatic light originating from a point source. &n

    		•
  • Q : Explain Boyle's law Boyle's law (R.

    Boyle's law (R. Boyle; 1662); Mariotte's law (E. Mariotte; 1676) - The product result of the volume and pressure of an ideal gas at constant (steady) temperature is constant.

    		•
  • Q : What is Magnus effect Magnus effect :

    Magnus effect: The rotating cylinder in a moving fluid drags a few of the fluid about with it, in its direction of rotation. This raises the speed in that area, and therefore the pressure is lower. Therefore, there is a total force on the cylinder in

    		•