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It seems scientists have created "Wooly mice" in a step to attempt to bring back the wooly mammoth, which is an extinct species, read more at Scientists create ‘woolly mice’ in a step to bring back the mammoth | CNN Do you think that next we should attempt to bring back the wooly mammoth from extinction?

1kg mass = 1kg weight? Not in Physics or Engineering! Only in the home, or in most commerce, loads are usually expressed in kilograms by custom. As a marine engineer, when a ship is taking on a load expressed in kilograms, it must be converted into force units( 1 kilogram = 9.8 Newtons ). All ship design work is done in Newtons. Only by using Newtons can the marine engineer know if the load is within the ship’s design parameters. Where's the proof? What exactly would you like to see proved? Remember, in science there are no absolute proofs; we work with tested and verified theory. If in the gravitational field of the Earth a mass weighs 1 kg (weight), then in the gravitational field of that mass the Earth weighs the same 1 kg (weight)! What is the mass of the Earth, and what is the mass that weighs 1 kg of weight? You are mixing up mass and weight. As I already mentioned, this is customary outside of science and engineering. This is a Science Forum so you should use the proper scientific definitions: Mass is the quantity of matter possessed by a body and is proportional to the volume and density of that body. The basic unit of mass is the kilogram. The kilogram can be defined in terms of a fixed value of the Planck constant, h, plus the existing definitions of the meter and the second. Weight of a body is the gravitational force on the mass of that body; usually the force of gravitational attraction exerted on the body by the Earth. The basic unit of weight is the Newton, which is a unit of Force. Calculation of the weight of a one kilogram mass on the surface of the Earth: Weight is a Force. Near the Earth’s surface: Weight [N] = Mass [Kg] X g [9.8 m/s^2] Where g is the Earth’s acceleration = GMe/r^2 G is the gravitational constant = 6.67E-11, Me = Earth's mass 5.98E24 kg, r = Earth’s radius 6.37E6 m A one kilogram mass near the surface of the Earth weighs 9.81 Newtons. Now reverse the calculation and calculate the weight of the Earth on a one kilogram mass: Weight [N] = Mass [Kg] X g [9.8 m/s^2] Me X Gm/r^2 = 9.81 Newtons Me is Earth’s mass, m is the mass of the one kilogram object. Confirming Newton’s Third Law: Forces always exist in pairs in such a way that if body A exerts a force on body B, then body B exerts an equal force on body A, with these forces being in opposite directions. One caveat to keep in mind; the distance between the 1 kg mass and the Earth is always the radius of the Earth, so r is the same in both calculations. The below in brackets is gibberish and I will not respond to such: [The gravitational force is the sum of the forces in those two gravitational fields: The total gravitational force FG between two gravitational fields is 2 kg (weight). FG = 1 kg + 1 kg = 2 kg (weight) = 2 * 9.81 N While our convention for the relationship between weight and mass says: FG = 1 kg mass * 9.81 kg(m^-1)(s^-2) = 9.81 N = 1 kg weight (free fall – g – relative acceleration!)] Physicists today claim: “1 kg of mass = 1 kg of weight,” as if it were some natural law ?! Physicists claim no such thing. More gibberish follows: [The above convention was adopted without prior definition of what is mass and what is weight! The concept of relative and absolute acceleration in the gravitational field is also not defined! When a mass is at rest (on scale), it is acted upon by an absolute acceleration a! Absolute acceleration a is equal to half of the relative acceleration g! FG/2 = 1kg weight * relative acceleration (on scale)] How does the scale weigh 1 kg of weight? Finally, a reasonable question! The scale indicates 1 Kg of “weight” because that is how the dial and spring are calibrated because most people are accustomed to having their “weight” expressed in kilograms. This is technically incorrect but it is far enough outside the field of Physics and Engineering that it has become an acceptable custom. You will never catch a marine engineer designing the hull of a ship based on kilograms of force! (At least I hope not!) Designers use Newtons for force and Kilograms for mass. Warning, more gibberish follows: [The gravitational force of 2 kg weight is divided into the force of 1 kg weight in the center of gravity of the scale and 1 kg weight of the mass we are weighing! Therefore, only the relative acceleration g/2 acts on the mass at rest! Therefore it will be: m * a = 1 kg (weight) a = g/2 m * g/2 = 1 kg (weight) m * g = 2 kg (weight) that is, our convention for the ratio of mass to weight should be: m * g/2 = 1 kg (weight) m/2 * g = 1 kg (weight) = 9.81 N From here Newton’s second law would be (w = weight, m = mass): w/2 * g = m * g , w/2 = m , whence the ratio of the actual mass m to the weight w is equal to: w/m = 2/1 (1 kg of weight = ½ kg of mass),(weight and mass are not equal and are not the same!) therefore Newton’s Law of Force should be corrected to F = w/2 * a , if the mass is entered using the weight w. In calculations where mass is calculated, all weights should be divided by two to get the correct masses!] Where is the mistake? In my opinion, your biggest mistake is questioning Newton’s Laws without first trying to understand them. I do admit that the unfortunate popular custom of expressing weight in kilograms is confusing. However, most people are not scientifically or mathematically literate enough to know that this is wrong and their weight should be expressed in Newtons.