--%>
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 Lumen or SI unit of luminous flux

    Lumen: lm: The derived SI unit of luminous flux, stated as the luminous flux produced by a uniform point source of 1 cd releasing its luminous energy over a solid angle of 1 sr; it therefore has units of cd sr.

    		•
  • Q : Information in physics What do you mean

    What do you mean by the term information in physics?

    		•
  • Q : Define Photovoltaics Photovoltaics (PV)

    Photovoltaics (PV): It transform light directly into electricity. The typical current residential installation of 12m2 could produce around 1,300 kWh pa with a peak of around 1.9kW, though larger and more efficient installations are possibl

    		•
  • Q : What is Kirchhoffs law of radiation

    Kirchhoff's law of radiation (G.R. Kirchhoff): The emissivity of a body is equivalent to its absorbptance at similar temperature.

    		•
  • Q : Define Newton or SI unit of force

    Newton: N (after Sir I. Newton, 1642-1727): The derived SI unit of force, stated as the force needed to give a mass of 1 kg of an acceleration of 1 m/s2; it therefore has units of kg m/s2.

    		•
  • Q : Define Pauli Exclusion Principle Pauli

    Pauli Exclusion Principle (W. Pauli; 1925): No two similar fermions in a system, like electrons in an atom, can contain an identical set of the quantum numbers.

    		•
  • Q : Law of Lamberts Cosine State the law of

    State the law of Lamberts Cosine? Describe briefly?

    		•
  • Q : What is Gray Gray : Gy (after L.H.

    Gray: Gy (after L.H. Gray, 1905-1965): The derived SI unit of engrossed dose, stated as the absorbed dose in which the energy per unit mass communicated to the matter by the ionizing radiation is 1 J/kg; it therefore has units of J/kg

    		•
  • Q : Explain Joules laws and Joule's

    Joule's laws (J.P. Joule) Joule's first law: The heat Q generated whenever a current I flows via a resistance R for a specified time t is specified by: Q = I2

  • Q : Current through resistors How do I find

    How do I find out a maximum current flowing through a resistor with just the resistance of the resistor and it's power rating?

    		•