--%>
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 : Newtons laws of motion Briefly

    Briefly illustrate all the Newton s laws of motion?

    		•
  • Q : Explain Null experiment Null

    Null experiment: The experiment which, after being performed, yields no outcome. The null experiments are just as significant as non-null experiments; when current theory predicts an observable result (or predicts there must be no observable result),

    		•
  • Q : Explain Stefan-Boltzmann law

    Stefan-Boltzmann law (Stefan, L. Boltzmann): The radiated power P (that is the rate of emission of electromagnetic energy) of a hot body is proportional to the radiating surface area, A, and the 4th power of the thermodynamic temperature, T. The const

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

    What do you mean by the term nucleus? Describe in brief.

    		•
  • Q : Explain Archimedes' principle What is 

    What is Archimedes' principle? A body which is submerged in a fluid is buoyed up by a force equivalent in magnitude to the weight of the fluid which is displaced, and directed upward all along a line via the c

    		•
  • Q : How asteroids are formed Explain how

    Explain how asteroids are formed? Describe.

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

    What do you mean by the term density? Briefly explain it.

    		•
  • Q : What is Negative feedback principle

    Negative feedback principle: It is the idea that in a system where there are self-propagating situations, those new situations tend to act against formerly existing situations. Such a principle is in actuality a restatement of the conservation law.

    		•
  • 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 : Calculating current in magnetically

    For the magnetically coupled circuit in Figure a, calculate I1 and I2. If the dotted terminals in are changed so that the circuit now becomes that in Figure b, re-calculate I1 and I2.