--%>
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 Determinism principle

    Determinism principle: The principle that when one knows the state to an unlimited accuracy of a system at one point in time, one would be capable to predict the state of that system with unlimited accuracy at any other time, past or the future. For i

    		•
  • Q : What is Roche limit Roche limit : The

    Roche limit: The position about a massive body where the tidal forces due to the gravity of the primary equivalent or exceed the surface gravity of a specified satellite. Within the Roche limit, such a satellite will be interrupted by tides.

    		•
  • 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 : 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 : Explain the cause of Brownian motion

    Briefly define or explain the cause of Brownian motion?

    		•
  • Q : Explain Planck radiation law Planck

    Planck radiation law: The law which explained blackbody radiation better than its precursor, therefore resolving the ultraviolet catastrophe. This is based on the supposition that electromagnetic radiation is quantized.

    Q : Define Eddington limit Eddington limit

    Eddington limit (Sir A. Eddington): The hypothetical limit at which the photon pressure would surpass the gravitational attraction of a light-emitting body. That is, a body emanating radiation at bigger than the Eddington limit would

    		•
  • Q : Define Systeme Internationale d'Unites

    Systeme Internationale d'Unites (SI): The rationalized and coherent system of units derived from the m.k.s. system (that itself is derived from metric system) in common utilization in physics nowadays.

    		•
  • Q : What is neutral buoyancy What do you

    What do you mean by the term neutral buoyancy? Briefly illustrate it.

    		•
  • Q : Explain quantum physics why quantum

    why quantum physics is studied? give me some of topics

    		•