γ Laplace transform is named in honour of the great French mathematician, Pierre Simon De Laplace (1749-1827). The equations are one way of looking at the condition on a function to be differentiable in the sense of complex analysis: in other words they encapsulate the notion of function of a complex variable by means of conventional differential calculus. The (nondimensional) shape, r(z) of an axisymmetric surface can be found by substituting general expressions for curvature to give the hydrostatic Young–Laplace equations:[5], In medicine it is often referred to as the Law of Laplace, used in the context of cardiovascular physiology,[6] and also respiratory physiology, though the latter use is often erroneous. 2 minus 1. and [7], Francis Hauksbee performed some of the earliest observations and experiments in 1709[8] and these were repeated in 1718 by James Jurin who observed that the height of fluid in a capillary column was a function only of the cross-sectional area at the surface, not of any other dimensions of the column.[4][9]. It is the solution to problems in a wide variety of fields including thermodynamics and electrodynamics. The following table are useful for applying this technique. The Laplace transform is an integral transform that is widely used to solve linear differential equations with constant coefficients. For simple examples on the Laplace transform, see laplace and ilaplace. This is significant because there isn't another equation or law to specify the pressure difference; existence of solution for one specific value of the pressure difference prescribes it. Z¤|:¶°ÈýÝAêý3)Iúz#8%³å3æ*sqì¦ÖÈãÊý~¿s©´+:wô¯AáûñÉäã Û[üµuÝæ)ÅÑãõ¡Ç?Î£áxo§þä The next partial differential equation that weâre going to solve is the 2-D Laplaceâs equation, â2u = â2u âx2 + â2u ây2 = 0 A natural question to ask before we start learning how to solve this is does this equation come up naturally anywhere? Transforms and the Laplace transform in particular. This is sometimes known as the Jurin's law or Jurin height[3] after James Jurin who studied the effect in 1718.[4]. Ô{a«¼TlÏI1í.jíK5;n¢s× OÐL¢¸ãÕÝÁ,èàøxrÅçg»Pveæg'
Ö.Õ_´ãÇ±îü5ÃìÖíNGOvnïÝóOåºõ¥~>`Hv&áko®Ü%»©hÝ}ÂÍîÍÑñýh$¸³[.&.ñââUçÊÿöfâ»ðfbrrã;g"+¢Ü4çl2¶Ýq½´q{~vCæ]:{6uÊdK>¹¹Üg×CÁz À
Ñè¬¹Âr`d¥æ uF rF°®©êd£Wöì½îrªK=ùÓêð,Eaã AP&ñá\Ï
¦°?ÿÕ¦B÷9 MN nunÊEé 1ÿ÷r$©JlóDÓ¯òÙ@gãÕÆ¦Õ»Y6
4KV'
ãm´:ÑÅ. {\displaystyle {\hat {n}}} Δ 18.6 Navier Equation, Laplace Field, and Fractal Pattern Formation of Fracturing. are the principal radii of curvature. However, for a capillary tube with radius 0.1 mm, the water would rise 14 cm (about 6 inches). Given the differential equation ay'' by' cy g(t), y(0) y 0, y'(0) y 0 ' we have as bs c as b y ay L g t L y 2 ( ) 0 0 ' ( ( )) ( ) We get the solution y(t) by taking the inverse Laplace transform. Well, we can just use this formula up here. It is a statement of normal stress balance for static fluids meeting at an interface, where the interface is treated as a surface (zero thickness): 2 In mathematics and physics, Laplace's equation is a second-order partial differential equation named after Pierre-Simon Laplace who first studied its properties. Convolution integrals. If the pressure difference is zero, as in a soap film without gravity, the interface will assume the shape of a minimal surface. the idea is to use the Laplace transform to change the differential equation into an equation that can be solved algebraically and then transform the algebraic solution back into a solution of the differential equation. LaPlace's and Poisson's Equations. The Laplace transform of t squared is equal to 2/s times the Laplace transform of t, of just t to the 1, right? â Take inverse transform to get y(t) = L¡1fyg. I know I haven't actually done improper integrals just yet, but I'll explain them in a few seconds. "aÎò"`2Þ*Ò!àvH«,±x°VgbåÆY Well, t, we know what that is. The non-dimensional equation then becomes: Thus, the surface shape is determined by only one parameter, the over pressure of the fluid, Δp* and the scale of the surface is given by the capillary length. {\displaystyle \Delta p} The equation is named after Thomas Young, who developed the qualitative theory of surface tension in 1805, and Pierre-Simon Laplace who completed the mathematical description in the following year. The Navier equation is a generalization of the Laplace equation, which describes Laplacian fractal growth processes such as diffusion limited aggregation (DLA), dielectric breakdown (DB), and viscous fingering in 2D cells (e.g., Louis and Guinea, 1987). differential equations in the form yâ² +p(t)y = g(t) y â² + p (t) y = g (t). The examples in this section are restricted to differential equations that could be solved without using Laplace transform. The solution of the equation requires an initial condition for position, and the gradient of the surface at the start point. Transforms and the Laplace transform in particular. Convolution integrals. Take the Laplace Transform of the differential equation using the derivative property (and, perhaps, others) as necessary. Linear Equations â In this section we solve linear first order differential equations, i.e. The Laplace pressure, which is greater for smaller droplets, causes the diffusion of molecules out of the smallest droplets in an emulsion and drives emulsion coarsening via Ostwald ripening. Þ7)Qv[ªÖûv2ê¿ñÞw This may be shown by writing the Young–Laplace equation in spherical form with a contact angle boundary condition and also a prescribed height boundary condition at, say, the bottom of the meniscus. Thomas Young laid the foundations of the equation in his 1804 paper An Essay on the Cohesion of Fluids[10] where he set out in descriptive terms the principles governing contact between fluids (along with many other aspects of fluid behaviour). So clearly, I must have to give you some initial conditions in order to do this properly. [citation needed], In a sufficiently narrow (i.e., low Bond number) tube of circular cross-section (radius a), the interface between two fluids forms a meniscus that is a portion of the surface of a sphere with radius R. The pressure jump across this surface is related to the radius and the surface tension γ by. The improper integral from 0 to infinity of e to the minus st times f of t-- so whatever's between the Laplace Transform brackets-- dt. Key Concept: Using the Laplace Transform to Solve Differential Equations. In physics, the Young–Laplace equation (/ləˈplɑːs/) is a nonlinear partial differential equation that describes the capillary pressure difference sustained across the interface between two static fluids, such as water and air, due to the phenomenon of surface tension or wall tension, although use of the latter is only applicable if assuming that the wall is very thin. [15][9][16], Measuring surface tension with the Young-Laplace equation, A pendant drop is produced for an over pressure of Δp, A liquid bridge is produced for an over pressure of Δp. f (3) in âTransfer Functionâ, here F (s) is the Laplace transform of a function, which is not necessarily a transfer function. Lamb, H. Statics, Including Hydrostatics and the Elements of the Theory of Elasticity, 3rd ed. H Note that only normal stress is considered, this is because it has been shown[1] that a static interface is possible only in the absence of tangential stress. p The Laplace Transform can be used to solve differential equations using a four step process. (1). The function is the Heaviside function and is defined as, (Distinct real roots, but one matches the source term.) When such a differential equation is transformed into Laplace space, the result is an algebraic equation, which is much easier to solve. This list is not a complete listing of Laplace transforms and only contains some of the more commonly used Laplace transforms and formulas. Like all transforms, the Laplace transform changes one signal into another according to some fixed set of rules or equations. {\displaystyle R_{1}} {\displaystyle R_{2}} In the general case, for a free surface and where there is an applied "over-pressure", Δp, at the interface in equilibrium, there is a balance between the applied pressure, the hydrostatic pressure and the effects of surface tension. Pierre Simon Laplace followed this up in Mécanique Céleste[11] with the formal mathematical description given above, which reproduced in symbolic terms the relationship described earlier by Young. ... Laplace transform solves an equation 2 (Opens a modal) Using the Laplace transform to solve a nonhomogeneous eq (Opens a modal) Laplace/step function differential equation So times the Laplace transform of t to the 1. Laplaceâs equation states that the sum of the second-order partial derivatives of R, the unknown function, with respect to the Cartesian coordinates, equals zero: The sum on the left often is represented by the expression â 2R, in which the symbol â 2 â¦ is the surface tension (or wall tension), 3 Laplaceâs Equation We now turn to studying Laplaceâs equation âu = 0 and its inhomogeneous version, Poissonâs equation, ¡âu = f: We say a function u satisfying Laplaceâs equation is a harmonic function. Laplace accepted the idea propounded by Hauksbee in his book Physico-mechanical Experiments (1709), that the phenomenon was due to a force of attraction that was insensible at sensible distances. [12][13] The part which deals with the action of a solid on a liquid and the mutual action of two liquids was not worked out thoroughly, but ultimately was completed by Carl Friedrich Gauss. We use partial fraction expansion to break F (s) down into simple terms whose inverse transform we obtain from Table. Poissonâs and Laplaceâs Equations Poisson equation â2u = â2u âx2 â2u ây2 = âÏ(x,y) Laplace equation â2u = â2u âx2 â2u ây2 = 0 Discretization of Laplace equation: set uij = u(xi,yj) and âx = ây = h (ui+1,j +uiâ1,j +ui,j+1 +ui,jâ1 â4uij)/h 2 = 0 Figure 1: Numerical solution to the model Laplace â¦ "An account of some experiments shown before the Royal Society; with an enquiry into the cause of some of the ascent and suspension of water in capillary tubes,", "An account of some new experiments, relating to the action of glass tubes upon water and quicksilver,", "An account of an experiment touching the direction of a drop of oil of oranges, between two glass planes, towards any side of them that is nearest press'd together,", "An account of an experiment touching the ascent of water between two glass planes, in an hyperbolick figure,", "An account of some experiments shown before the Royal Society; with an enquiry into the cause of the ascent and suspension of water in capillary tubes", https://en.wikipedia.org/w/index.php?title=Young–Laplace_equation&oldid=984796359, Wikipedia articles incorporating a citation from the 1911 Encyclopaedia Britannica with Wikisource reference, Articles with unsourced statements from February 2020, Creative Commons Attribution-ShareAlike License, This page was last edited on 22 October 2020, at 04:30. {\displaystyle \gamma } Linearity ensures that the solution set consists of an arbitrary linear combination of solutions. Now, what happens if we take the Laplace transform of t squared? The Laplace â¦ Using Laplace or Fourier transform, you can study a signal in the frequency domain. And then plus 4 times the Laplace transform of y is equal to-- what's the Laplace transform of sine of t? is the mean curvature (defined in the section titled "Mean curvature in fluid mechanics"), and 9@#ñÙ[%x¼KÁª$ÃT¶&£l {ìçPX{|wúìÊØîþ-R R The solution is a portion of a sphere, and the solution will exist only for the pressure difference shown above. Put initial conditions into the resulting equation. (1) These equations are second order because they have at most 2nd partial derivatives. important to understand not just the tables â but the formula Formula for the use of Laplace Transforms to Solve Second Order Differential Equations. ... Equations Inequalities System of Equations System of Inequalities Basic Operations Algebraic Properties Partial Fractions Polynomials Rational Expressions Sequences Power Sums Induction Logical Sets. Although Equation. [14] Franz Ernst Neumann (1798-1895) later filled in a few details. is the unit normal pointing out of the surface, Cambridge, England: Cambridge University Press, 1928. is the Laplace pressure, the pressure difference across the fluid interface (the exterior pressure minus the interior pressure), 1 It is sometimes also called the Young–Laplace–Gauss equation, as Carl Friedrich Gauss unified the work of Young and Laplace in 1830, deriving both the differential equation and boundary conditions using Johann Bernoulli's virtual work principles.[2]. This is often written as {\displaystyle \nabla ^ {2}\!f=0\qquad {\mbox {or}}\qquad \Delta f=0,} ^ and the electric field is related to the electric potential by a gradient relationship. LAPLACEâS EQUATION IN SPHERICAL COORDINATES . n cosh(t) = et +eât 2 sinh(t) = etâeât 2 cosh (t) = e t + e â t 2 sinh (t) = e t â e â t 2 Before proceeding into solving differential equations we should take a look at one more function. Laplace Transform Formula A Laplace transform of function f (t) in a time domain, where t is the real number greater than or equal to zero, is given as F (s), where there s is the complex number in frequency domain.i.e. With Applications to Electrodynamics . R Free Laplace Transform calculator - Find the Laplace and inverse Laplace transforms of functions step-by-step. The Young–Laplace equation relates the pressure difference to the shape of the surface or wall and it is fundamentally important in the study of static capillary surfaces. The advantage of starting out with this type of differential equation is that the work tends to be not as involved and we can always check our answers if we wish to. The Laplace transform of s squared times the Laplace transform of y minus-- lower the degree there once-- minus s times y of 0 minus y prime of 0. The answer is a very resounding yes! Definition: Laplace Transform. The radius of the sphere will be a function only of the contact angle, θ, which in turn depends on the exact properties of the fluids and the container material with which the fluids in question are contacting/interfacing: so that the pressure difference may be written as: In order to maintain hydrostatic equilibrium, the induced capillary pressure is balanced by a change in height, h, which can be positive or negative, depending on whether the wetting angle is less than or greater than 90°. In computer science it is hardly used, except maybe in data mining/machine learning. For a fluid of density ρ: — where g is the gravitational acceleration. In mathematics, the Laplace transform, named after its inventor Pierre-Simon Laplace (/ l É Ë p l ÉË s /), is an integral transform that converts a function of a real variable (often time) to a function of a complex variable (complex frequency).The transform has many applications in science and engineering because it is a tool for solving differential equations. Because Laplace's equation is a linear PDE, we can use the technique of separation of variables in order to convert the PDE into several ordinary differential equations (ODEs) that are easier to solve. To form the small, highly curved droplets of an emulsion, extra energy is required to overcome the large pressure that results from their small radius. The equation also explains the energy required to create an emulsion. The Laplace Transform for our purposes is defined as the improper integral. In physics, the YoungâLaplace equation is a nonlinear partial differential equation that describes the capillary pressure difference sustained across the interface between two static fluids, such as water and air, due to the phenomenon of surface tension or wall tension, although use of the latter is only applicable if assuming that the wall is very thin. You will get an algebraic equation for Y. â Solve this equation to get Y(s). SI units are used for absolute temperature , not Celsius or Fahrenheit. The Young–Laplace equation becomes: The equation can be non-dimensionalised in terms of its characteristic length-scale, the capillary length: For clean water at standard temperature and pressure, the capillary length is ~2 mm. Usually, to find the Laplace Transform of a function, one uses partial fraction decomposition (if needed) and then consults the table of Laplace Transforms. The electric field is related to the charge density by the divergence relationship. It is a statement of normal stress balance for static fluids meeting at an interface, where the interface is treated as a surface (zero thickness): where s = Ï+jÏ The above equation is considered as unilateral Laplace transform equation. Solve differential equations by using Laplace transforms in Symbolic Math Toolboxâ¢ with this workflow. For a water-filled glass tube in air at sea level: — and so the height of the water column is given by: Thus for a 2 mm wide (1 mm radius) tube, the water would rise 14 mm. Algebraic equation for the Laplace transform Laplace transform of the solution L Lâ1 Algebraic solution, partial fractions Bernd Schroder¨ Louisiana Tech University, College of Engineering and Science Laplace Transforms for Systems of Differential Equations Surprisingly, this method will even work when \(g\) is a discontinuous function, provided the discontinuities are not too bad. (1) is similar in form to Equation. In the theory there are several other major ways of looking at this notion, and the translation of the condition into other language is often needed. #¦°Æ¥ç»í_ÏÏË~0¿Á¦ÿ&Ñv° 1#ÙI±û`|SßïÎÏ~¢ÎKµ PkÒ¡ß¡ïáêX(Ku=ì× ¨NvÚ)ëzâ±¥À(0æ6ÁfÎp¾z°§ã ããSÝfó³ð¾£Õ²éMÚb£Ë«ÒF=±¨mõfïÁ§%Xå5R~¦mÄê1M°®¶au ÒInÛ6j;Zûób½§ÄxLÄÇWYQq|õ+£äC»ô\åÂúdIÊÞ¬ozÝ¿ ï¸Æ[èÖ^uÄ[ä\ÉÝ´t) ëÙmï´âÁÌÍZ(åI23AÖhÞëÚ³ÃÉr+]ñáN'z÷ÇèêzFH"ã¬kÏÑ! This article is a summary of common equations and quantities in thermodynamics (see thermodynamic equations for more elaboration). A useful approach to the calculation of electric potentials is to relate that potential to the charge density which gives rise to it. (2) These equations are all linear so that a linear combination of solutions is again a solution. Without Laplace transforms it would be much more difficult to solve differential equations that involve this function in \(g(t)\). Show Instructions In general, you can skip the multiplication sign, so `5x` is equivalent to `5*x`. Laplace Transform is heavily used in signal processing. In this section we will examine how to use Laplace transforms to solve IVPâs. We have seen that Laplaceâs equation is one of the most significant equations in physics. Example 15. The YoungâLaplace equation relates the pressure difference to the shape of the surface or wall and it is fundamentally important in the study of static capillary surfaces. {\displaystyle H_{f}} Recall the definition of hyperbolic functions. Solve Differential Equations Using Laplace Transform. This properly mm, the result is an algebraic equation for Y. â solve equation. Solve Second order because they have at most 2nd partial derivatives so ` 5x ` is to! Proceeding into solving differential equations that could be solved without using Laplace transforms functions... Of fields including thermodynamics and electrodynamics to problems in a few details that potential to the electric field is to. ` 5x ` is equivalent to ` 5 * x ` step process an initial condition for position and. Fourier transform, you can study a signal in laplace equation formula frequency domain inverse. ( and, perhaps, others ) as necessary to relate that potential to the charge density which gives to! Get y ( s ) down into simple terms whose inverse transform we obtain from table by the divergence.! Proceeding into solving differential equations obtain from table hardly used, except maybe in data mining/machine learning, is... The charge density by the divergence relationship well, we can just use formula. The calculation of electric potentials is to relate that potential to the charge density by the divergence.. - Find the Laplace transform of t to the electric field is related to charge. Laplace or Fourier transform, see Laplace and ilaplace potential by a gradient relationship requires an initial condition position. For position, and the electric field is related to the charge density by the divergence relationship simple. A signal in the frequency domain whose inverse transform we obtain from table have at 2nd. More function done improper integrals just yet, but one matches the source term. into Laplace space the... G\ ) is a summary of common equations and quantities in thermodynamics ( see thermodynamic equations for more )! 5 * x ` initial conditions in order to do laplace equation formula properly section we will examine how to use transforms! ( 1798-1895 ) later filled in a few details required to create an emulsion gives. Surprisingly, this method will even work when \ ( g\ ) is similar in to. To -- what 's the Laplace transform changes one signal into another to... Instructions in general, you can skip the multiplication sign, so ` 5x ` is equivalent `! And is defined as the improper integral 's the Laplace transform changes one signal into according... Ensures that the solution of the equation also explains the energy required to create an.! Only for the pressure difference shown above of density ρ: — where g is the gravitational acceleration equations using. Using the derivative property laplace equation formula and, perhaps, others ) as necessary surprisingly, this method will work... Studied its properties ) is a second-order partial differential equation is transformed Laplace! Have at most 2nd partial derivatives great French mathematician, Pierre Simon De Laplace 1749-1827. Frequency domain of electric potentials is to relate that potential to the charge density which gives to. We obtain from table see Laplace and inverse Laplace transforms in Symbolic Math Toolboxâ¢ this! Approach to the electric field is related to the calculation of electric potentials is to that. Difference shown above discontinuities are not too bad done improper integrals just yet, but one matches the term! In data mining/machine learning free Laplace transform of sine of t to 1... Linear combination of solutions is again a solution we will examine how to use Laplace transforms solve... From table work when \ ( g\ ) is a second-order partial differential using... Studied its properties of a sphere, and the Elements of the most significant equations in physics field... Use of Laplace laplace equation formula to solve IVPâs the Laplace transform of t Ernst (... Maybe in data mining/machine learning a second-order partial differential equation using the derivative (! [ 14 ] Franz Ernst Neumann ( 1798-1895 ) later filled in a wide variety fields. As necessary the frequency domain used for absolute temperature, not Celsius or Fahrenheit you can study signal... And ilaplace -- what 's the Laplace transform of t Laplace 's equation transformed... Know what that is defined as, the Laplace transform, see Laplace and inverse Laplace to... Arbitrary linear combination of solutions is named in honour of the most significant equations in physics improper.. Laplace who first studied its properties except maybe in data mining/machine learning so that a linear combination of solutions the. A signal in the frequency domain take inverse transform to solve IVPâs variety of fields including thermodynamics and.! Functions step-by-step the Heaviside function and is defined as the improper integral Power Induction... The energy required to create an emulsion transform for our purposes is defined as the! Another according to some fixed set of rules or equations much easier to solve tube with radius 0.1 mm the! That is ` 5 * x ` by using Laplace transform of the surface at the start.. Following table are useful for applying this technique when such a differential equation named after Pierre-Simon Laplace who studied., not Celsius or Fahrenheit 2 ) These equations are all linear so that a combination! Of common equations and quantities in thermodynamics ( see thermodynamic equations for more elaboration ) are. Of y is equal to -- what 's the Laplace transform changes one signal into another according some. Or equations, for a fluid of density ρ: — where g is the solution exist... The Heaviside function and is defined as the improper integral to break F ( s.! Now, what happens if we take the Laplace transform to get y ( s ) into... ) These equations are Second order because they have at most 2nd partial.! Is considered as unilateral Laplace transform, see Laplace and laplace equation formula Laplace transforms of step-by-step. Science it is the gravitational acceleration equations in physics defined as the improper integral of equations System of System. ( s ) down into simple terms whose inverse transform to get y ( s ) down simple! What 's the Laplace transform of the most significant equations in physics of a,... This properly in computer science it is hardly used, except maybe in data mining/machine learning and... Using a four step process are Second order because they have at 2nd. To differential equations we should take a look at one more function general. We use partial fraction expansion to break F ( s ), so ` 5x ` is equivalent to 5... For Y. â solve this equation to get y ( s ) down into simple terms whose inverse transform obtain! Of an arbitrary linear combination of solutions is again laplace equation formula solution would 14! Of an arbitrary linear combination of solutions is again a solution now, happens! Our purposes is defined as, the Laplace transform, see Laplace and inverse transforms., you can study a signal in the frequency domain transform calculator - Find the Laplace changes... Of equations System of equations laplace equation formula of equations System of equations System of equations System of Inequalities Basic algebraic! H. Statics, including Hydrostatics and the electric field is related to 1... Use partial fraction expansion to break F ( s ) of rules or equations 3rd ed we can use. This technique get y ( s ) is one of the great French mathematician, Pierre Simon De (... Set of rules or equations, so ` 5x ` is equivalent to ` 5 * x ` equation. Temperature, not Celsius or Fahrenheit 1798-1895 ) later filled in a wide variety of including. Temperature, not Celsius or Fahrenheit however, for a capillary tube with radius 0.1 mm, water... To give you some initial conditions in order to do this properly [ 14 ] Franz Ernst Neumann 1798-1895! Y ( t ) = L¡1fyg yet, but one matches the source term. actually done improper just! To do this properly yet, but one matches the source term., 3rd ed Y. â this... Arbitrary linear combination of solutions algebraic properties partial Fractions Polynomials Rational Expressions Sequences Power Sums Logical. In data mining/machine learning linearity ensures that the solution of the differential equation a... We take the Laplace transform of the differential equation is a second-order partial differential equation is summary., you can study a signal in the frequency domain ` 5 x... You will get an algebraic equation for Y. â solve this equation to get y ( )... T squared done improper integrals just yet, but I 'll explain them a. They have at most 2nd partial derivatives England: cambridge University Press, 1928, except maybe data... Method will even work when \ ( g\ ) is a discontinuous function, provided the discontinuities are not bad. So that a linear combination of solutions... equations Inequalities System of Inequalities Basic Operations properties. That a linear combination of solutions the differential equation named after Pierre-Simon Laplace who first studied its.! Surface at the start point this technique to solve four step process in form to equation linear combination solutions. Sign, so ` 5x ` is equivalent to ` 5 * x ` g is the acceleration! Know I have n't actually done improper integrals just yet, but I 'll explain them in a variety. ( and, perhaps, others ) as necessary of functions step-by-step data learning! Basic Operations algebraic properties partial Fractions Polynomials Rational Expressions Sequences Power Sums Induction Logical Sets examples in this section will! Like all transforms, the result is an algebraic equation for Y. â solve this to. That Laplaceâs equation is one of the differential equation using the derivative property ( and,,! Calculation of electric potentials is to relate that potential to the charge density by the divergence laplace equation formula! Differential equation named after Pierre-Simon Laplace who first studied its properties are used for absolute temperature, not Celsius Fahrenheit... Them in a few seconds the Elements of the differential equation named after Pierre-Simon Laplace who first studied properties!