Does the gravitational constant (G)?




Can the gravity, the force that keeps us on the Earth’s surface and binds the star among themselves, just take to change? Last measurement G, the so-called constant, which is the gravitational attraction between two objects, has issued an official result is higher than the current value.

Measurements of G are unreliable, so the constant changes periodically and the official value is an average. However, the recent rejection is particularly surprising, since very different from the official measure and it is very similar to the measurement made in 2001, of which you are unlikely to expect when you bet on the random error in the experiment.

It is possible that both experiments suffered from a hidden and constant errors, but the result makes us think about the possibility of an even more bizarre: that G itself may change. This is a fairly radical option, but if it is true, then we are one step closer to solving the mystery of a very large – dark energy , which accelerates the expansion of the universe remains elusive to scientists from the planet Earth.

“If G changed to a tiny value, it can be expected that G depends on the new field,” – says cosmologist Tony Padilla of the University of Nottingham in the UK. – “You can not even imagine that this field is important for dark energy.”

Twist the wire

According to Newton, the gravitational attraction between two objects is proportional to their masses and inversely proportional to the square of the distance between them. G sets the absolute value of the attraction. Constant measured for the first time in 1798 in his laboratory British scientist Henry Cavendish. He watched a device that twists the two wires with a known mass under the action of gravity.

Since different methods produce different values. It is assumed that this is due to a variety of experimental errors, and the official value of G is constantly updated with their account, because it is assumed that once all the values ​​converge.

Now a team led by Terry Quinn from the International Bureau of Weights and Measures (BIPM) in Paris, France, and Clive Speake of the University of Birmingham in the UK, G measured using two methods: the modern version of the Cavendish experiment, and the other, based on electrostatics. The obtained value of G was 240 parts a million more than the official, established in 2010.

Spring violets

All this is not the strangest thing – the last measurement, a result of 290 ppm below today’s official value. Strangeness that the last measurement of 21 ppm below the command Quinn obtained in 2001. Obviously, since the team was concerned to eliminate any source of error that could creep into the result in 2001. Therefore, no one expected such a coincidence.

Quinn convened a special conference on the gravitational constant of the Royal Society of London in the coming February, to discuss the problem.

“This promises to be very interesting,” – says James Hugh, an experimental physicist at the University of Glasgow in the UK. He has already proposed a three specific experiment. – “I believe that the experiment BIPM need to copy and produce in three laboratories on different continents, with the assistance of various experimenters and see if it will work the same result at all.”

But James Faller of the University of Colorado at Boulder, checked the G in 2010, relies on the error: “Error – like spring violets, they can occur in any of the experimental groups.”

Fifth force

The latter result could also be evidence that the force of gravity changes.

“It is logical to assume that either some of the experiments are wrong, or G is not a constant,” – says Mark Kasevich from Stanford University.

The oscillating G can be evidence of a different theory related to dark energy, the fifth fundamental, but so far hypothetical force, in addition to the four already known to us: gravity, electromagnetism, and the two nuclear powers. This force may cause the force of gravity to fluctuate, said Padilla. This result will certainly appeal to a good half of humanity.

In addition, it is likely that G remains constant, but the team Quinn withdrew its true value. This means that the actual value of G is higher than officially acknowledged, and it is also interesting in itself. So says Claire Berreydzh, cosmologist at the University of Nottingham.

“If the G bit more, we need to go back and redo all the calculations,” – she said. – “Stars burn up faster than we previously thought, because they require more energy to resist the gravitational forces.”

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Tags: universe , gravity , dark energy , Physics .


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