--%>
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 Magnetic monopole Magnetic

    Magnetic monopole: The hypothetical particle that comprises sources and sinks of the magnetic field. The magnetic monopoles have never been found, however would only cause pretty minor modifications to the Maxwell's equations. They also appear to be p

    		•
  • Q : Write a short note on diffuse reflection

    Write a short note on diffuse reflection?

    		•
  • 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 : 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 Tachyon Tachyon: The purely

    Tachyon: The purely speculative particle that is supposed to travel faster than light. According to Sir Einstein's equations of special relativity, a particle with imaginary rest mass and a velocity more than c would contain a real momentum and energy

    		•
  • 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 : Define Tau-theta paradox Tau-theta

    Tau-theta paradox (1950s): Whenever two distinct kinds of kaons, tau and theta (nowadays tau refers to a totally different particle) decay, tau decays into three particles, whereas the theta decays into two. The tau and theta vary onl

    		•
  • Q : Explain Einstein field equation

    Einstein field equation: The cornerstone of Einstein's general theory of relativity, associating the gravitational tensor G to the stress-energy tensor T by the simple equation: G = 8 pi T<

    		•
  • 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 : Possibility to obtain the electron Is

    Is it possible to obtain the electron (or come out) from the nucleus?

    		•