Was the calculation of the mass of the Universe really based on the value of Hubbell 's constant?
913651
Actually, the Hubble's Constant determines the rate of expansion of the universe, as well as the critical density for closure of the universe. This is based on Friedman's solutions to Einstein's Field Equations. He calculated that for a flat universe,\n\nρ(critical) = 3H^2/8πG, where H is the Hubble Constant\n\nTo determine the total amount of matter in the Universe (including baryons and dark matter), we have to measure it, and that measurement comes from the CMB (Cosmic Microwave Background). And it's been found that normal and dark matter only accounts for only about 26% of the critical density. This implies the existence of an additional form of energy to account for the remaining 74%. This is how "Dark Energy" was discovered.
681184
Paul Davies carried out observations of light of quasars at 10 to 12 billion light years away and as this light originated near the birth of the universe and has traveled to us it has passed through clouds with metal gases. This puts a fingerprint on the light we received. \n\nOn analyzing the fingerprint they came across a variation with two reasons. With the aid of Stephen Hawking's formula for black holes Davies Davies Analyzed one part and tweaked Hawking's formula for the other. The final answer they arrived at through elimination was the speed of light was slowing down. Davies suggests that the vacuum of space is changing to affect the speed of light.\n\nWill this affect Einstein's Special Theory of Relativity and it's significant formula E=mc^2. The short answer, in theoretical calculations at or near the speed of light or intense gravities there will be tiny variations but on the whole the formula will hold true.
750315
Newton just claimed that was true.  We have made millions of measurements which support the theory.  But I know no way of proving it.  A separate question is whether inertial mass equals gravitational mass.  Again, all the measurements we've ever taken support the idea, but we know no way to prove it.
800535
jinde, hi!\n\nwhat an amazing question!  i remember reading about this somewhere, so it took me so long to research it...\n\nsee, when we talk about weight, it varies from spot to spot in the universe.  you may weigh 60kgs on Earth.  but on the moon, you'd be 10kgs.  on Jupiter, you'd be 600000kgs!!!\n\nwhat we need to discuss is the mass of the object, because that would be the only thing that makes sense on the Galactic scale.  are you ready for the answer?  it's gonna be mind-boggling!\n\nThe Earth's mass is approximately 6,000,000,000,000,000,000,000,000 (6E+24) kilograms!!\n\ni know what you're next question will be?\n\n"How did they measure that?"  i have the answer for you!\n\nthe measurement of the planet's weight is derived from the gravitational attraction that the Earth has for objects near it.\n\nit turns out that any two masses have a gravitational attraction for one another. if you put two iron weights near each other, they will attract one another gravitationally. the attraction is extremely slight, but if your instruments are sensitive enough you can measure the gravitational attraction that they have on one another. from that measurement, you could determine the mass of the two objects. the same is true for two marbles too! but the attraction is even slighter because the amount of gravitational force depends on mass of the objects...\n\nNewton showed that, for spherical objects, you can make the simplifying assumption that all of the object's mass is concentrated at the center of the sphere... and the following equation expresses the gravitational attraction that two spherical objects have on one another :\nF = G * M1 * M2 / R2\n\n    * R is the distance separating the two objects.\n    * G is a constant that is 6.67259x10-11m3/s2 kg.\n    * M1 and M2 are the two masses that are attracting each other.\n    * F is the force of attraction between them. \n\nassume that Earth is one of the masses (M1) and a 1-kg sphere is the other (M2).  the force between them is 9.8 kg*m/s2 -- we can calculate this force by dropping the 1-kg sphere and measuring the acceleration that the Earth's gravitational field applies to it (9.8 m/s2)...\n\nthe radius of the Earth is 6,400,000 meters (6,999,125 yards)... if you plug all of these values in and solve for M1, you find that the mass of the Earth is 6,000,000,000,000,000,000,000,000 kilograms (6E+24 kilograms / 1.3E+25 pounds)...\n\nhope this made sense... and if it did, i hope it was useful to you...\n\ndo write me if you need more clarification...\n\nenjoy!
1172315
I don't think we understand either well enough at this point to answer the question. They are both singular in that they both are regions where General Relativity predicts its own breakdown, and as such requires us to come up with new physics to understand them. \n\nThe prediction of these singularities in both cases was shown by the beautiful mathematics discovered by Roger Penrose and Steven Hawking. \n\nNote the following Quote by physicist Lee Smolin.\n\n"It may be conjectured that each black hole of our universe leads to such a creation of a new universe and that, correspondingly, the big bang in our past is the result of the formation of a black hole in another universe." Lee Smolin\n\nOne of the reasons Lee Smolin comes up with this idea is that the constants that our universe is based on seems to be tuned to the production of Black Holes.  That is if you take the fundamental physical constants which we measure and tweak them, you get a reduction in the formation of Black Holes. This he argues is an indication that the birth of baby universes such as our own is directly connected with the existence of Black Holes.\n\nBut to know if there is a direct connection between black holes and baby universes, as Smolin has speculated, is well beyond our current understanding of physics. And the anthropic type arguments that Smolin makes could have other reasons for being true. Our universe is likely fine tuned for our existence for example, and the Black Holes just come along for the ride as it were.
695350
Yes.\n\nIn fact there is a very nice relationship that when you are below the surface of the Earth (assuming the Earth is a perfect sphere), your weight is proportional to your radius from the center. E.g. if you were 1/3 of the way to the center (2/3 from the center), you'd weigh 2/3 as much as you do on the surface.\n\nThe proof uses a variant of Gauss's law from electromagnetics (because Newton's equation for gravity and Coulomb's equation for charge have the same form). Without delving into advanced calculus, the gravity that affects you depends only on the earth in the sphere below you - everything at your altitude and above cancels out. Since the volume of a sphere is proportional to r^3, but the gravitational force is proportional to 1/r^2, the remaining term is simply r - so your weight is proportional to the radius, if you're inside a sphere.\n\nOf course this assumes that the Earth's weight is distributed evenly. However, it's close enough to even for most purposes.
328729
Well, if you want to break it down even more, the universe only consists of minscule, vibrating strings.  At least, that's the most widely accepted theory in fundamental physics right now.\n\nThe beauty of it all is how much complexity can arise from such simple fundamentals.
400480
Olliehunt has the right idea, but the expansion of the Universe during the first second (although probably less than that), was so incredibly fast, millions and millions of times faster than the speed of light, that the final figure he came up with is much smaller than what could be the actual size of the Universe.\n\nThe simple answer is, we don't know.  It's vast!
258042
Fact.  Sort of.\n\nWhat is a fact is that every single repeatable measurement of large scale mass shows a very large discrepancy between how much dynamical mass is there (that is to say how much gravity says is there), and how much we can account for using every trick we know (and some we don't).\n\nGalaxy rotation, galaxy cluster temperature, WMAP data, you name it, everything we do to measure dynamical mass of very large objects comes back with us missing large amounds of accountable mass.\n\nEither there is some form of "dark matter" or we are encountering some new aspect of Gravity.  Right now Dark Matter is winning out because no one has been able to come up with a new twist on gravity that gets things right.
890942
The gravitational constant is perhaps the most difficult physical constant to measure. In SI units, the 2002 CODATA recommended value of the gravitational constant is\n\n    G = &#92;left(6.6742 &#92;plusmn 0.0010 &#92;right) &#92;times 10^{-11} &#92; &#92;mbox{N} &#92; &#92;mbox{m}^2 &#92; &#92;mbox{kg}^{-2} &#92;,\n\n        = &#92;left(6.6742 &#92;plusmn 0.0010 &#92;right) &#92;times 10^{-11} &#92; &#92;mbox{m}^3 &#92; &#92;mbox{s}^{-2} &#92; &#92;mbox{kg}^{-1} &#92;,\n\nAnother authoritative estimate is given by the International Astronomical Union (see Standish, 1995)\nSo far so good, it works. Therefore it is proven 'Universal'.
965826
L = 8pi G rho/c^4 is the definition of the cosmo constant L (1/m^2); where c = light speed and rho is the energy density of the known universe in a vacuum.\n\nF = GmM/r^2 is the equation for the attraction force F between two masses m and M, r distance apart.\n\nL was created by Einstein to make his equations come out right.  By that, he meant the universe should be spherical (not flat or saddle shaped).  His original results showed a flat universe, and he just "knew" that was wrong; so on came L to fix the shape problem.\n\nF was the result of experiments by Newton.  Through observation, he found that the attractive force between two bodies was proportional to the inverse square of the distance between them and to the product of the magnitudes of the two masses.  That is, F varies as (~) (mV/r^2).  \n\nWhenever there is a proportionality, as in F ~ mM/r^2, there has to be a constant of proportionality.  In this case Newton called it G; so that F ~ mM/r^2 becomes F = GmM/r^2 when the constant is inserted.\n\nThe G in both equations is the same constant.  But Sir Newton came upon it long before Einstein found it could be used in his equations and the calculation of L.  So there is no way that Newton (1642-1727) could know about Einstein's (1879-1955) use of it much later.
821744
What is the mass of the Universe? Also how can you prove that this is the true mass of the Universe?\n\nAs nobody knows the size of the universe, one cannot really talk about the mass of the universe, though one can talk about the mass of the observable universe. What is normally sought after is the density of matter in the universe (which is the mass per unit volume). This is what is important in determining the fate of the universe: whether it will collapse one day or whether it will continue expanding forever.\n\nThe density of matter in the universe can be measured by various means, which are too technical to go into at this point: people measure the density by studying the fluctuations in the Cosmic Microwave Background, superclusters, Big Bang nucleosynthesis, etc.\n\nAccording to these studies, the density of matter in the universe is about 3 x 10-30 g/cm3, which means that it is 300 billion billion billion times less dense than water. Note that this includes the contribution of dark matter and so the density of luminous matter (that we see as stars and galaxies) is only about one-tenth of the figure given above.\n\nNow, the size of the observable universe is about 14 billion light years, and using the above value of density gives you a mass (dark and luminous matter) of about 3 x 10^55 g, which is roughly 25 billion galaxies the size of the Milky Way.
1011745
The mass of the earth has been calculated as 6 x 10^24 kilograms. (Mass is a little different than weight, but let's not get into that.) Here's a link on how this calculation was done.
103563
Curiouscat is way kewl.....good answer on her part.\n\nE = mc^2 has been proven valid over and over again. Altho, in science, everything is theory, because someone may come along and find a flaw or correction.\n\nHowever up the present, this equation is rock solid.
1005839
We don't know. The physics were different at that point in the universe's development.  That doesn't mean that the big bang is wrong.  All we can say to answer your specific question is, we don't know.\n\nThe same way that we don't know why electrons only move in discrete  jumps in their orbitals or why the gravitational constant is what it is.  That doesn't make the atomic theory wrong or our theories of gravity wrong.  Just incomplete.
588727
The equation E=MC2 is the derivation from Einstein's relativity theory. this is not a case of the classic mechanics. this equation explains the value of energy of an atom. \n\nE-> Energy\nM-> mass of the atom\nC-> speed of the light.\n\nin this only speed of the light is constant. the mass differs by frame to frame in accordance to theory of relativity. so the energy of the atoms also differs with frame to frame. but this equation is not fully correct and Lorentz had made corrections to it. \n\nAnybody who can prove this equation as a total wrong thing with strong evidences will be announced as the greatest of the universe..
406596
no idea...but I think you use the formula (Gravitational constant x mass 1 x mass 2) / distance squared