--%>
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 Olbers paradox Olbers' paradox

    Olbers' paradox (H. Olbers; 1826): If the Universe is infinite, consistent, and unchanging then the whole sky at night would be bright -- concerning as bright as the Sun. The further you stared out into space, the more stars there would be, and theref

    		•
  • Q : Explain Stern-Gerlach experiment

    Stern-Gerlach experiment (O. Stern, W. Gerlach; 1922): The experiment which explains the features of spin (that is intrinsic angular momentum) as a different entity apart from the orbital angular momentum.

    		•
  • Q : Define Metre or SI unit of length Metre

    Metre: meter; m: The basic SI unit of length, stated as the length of the path traveled by light in vacuum throughout a period of 1/299 792 458 s.

    		•
  • Q : Explain Drake equation 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

    		•
  • Q : Explain Hawking radiation Hawking

    Hawking radiation (S.W. Hawking; 1973): The theory which black holes emit radiation similar to any other hot body. The virtual particle-antiparticle pairs are continuously being made in supposedly empty space. Infrequently, a pair wil

    		•
  • Q : Polar Materials The molecules of many

    The molecules of many dielectrics possess an electric dipole moment without having an external electric field. In such molecules centres of their positive and negative charges are displaced with respect to each other and therefore form a dipole. Such materials are kno

    		•
  • Q : Problem on Orbit cycle Calculate the

    Calculate the hot and cold temperature after 25 orbits. Assume a 100kg spherical spacecraft made of aluminum. Assume that the spacecraft is in an equatorial orbit. How is calculation 1 different for a spacecraft in a 90 degree (polar) orbit?

    		•
  • 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 : Plasma globe AD advantages and

    advantages and disadvantages of a plasma globe

    		•
  • Q : Difference between the electron and a

    Write down the vital difference between the electron and a beta ray?

    		•