Earth gone slow than earlier its main reason with proof is??
Answers
Earth's rotation is slowing slightly with time; thus, a day was shorter in the past. This is due to the tidal effects the Moon has on Earth's rotation. Atomic clocks show that a modern day is longer by about 1.7 milliseconds than a century ago, slowly increasing the rate at which UTC is adjusted by leap seconds.
By Chris Baraniuk
2 May 2016
It was September 2011 and physicist Antonio Ereditato had just shocked the world.
The announcement he had made promised to overturn our understanding of the Universe. If the data gathered by 160 scientists working on the OPERA project were correct, the unthinkable had been observed.
Particles – in this case, neutrinos – had travelled faster than light.
This time the scientists got it wrong
According to Einstein's theories of relativity, this should not have been possible. And the implications for showing it had happened were vast. Many bits of physics might have to be reconsidered.
Although Ereditato said that he and his team had "high confidence" in their result, they did not claim that they knew it was completely accurate. In fact, they were asking for other scientists to help them understand what had happened.
In the end, it turned out the OPERA result was wrong. A timing problem had been caused by a poorly connected cable that should have been transmitting accurate signals from GPS satellites.
There was an unexpected delay in the signal. As a consequence, the measurements of how long the neutrinos took to travel the given distance were off by about 73 nanoseconds, making it look as though they had whizzed along more quickly than light could have done.
Despite months of careful checks prior to the experiment, and plentiful double-checking of the data afterwards, this time the scientists got it wrong. Ereditato resigned, though many pointed out that mistakes like these happen all the time in the hugely complex machinery of particle accelerators.
Why was it such a big deal to suggest – even as a possibility – that something had travelled faster than light? And are we really sure that nothing can?
We cannot go as fast as light (Credit: SCPhotos/Alamy Stock Photo)
We cannot go as fast as light (Credit: SCPhotos/Alamy Stock Photo)
Let's take the second of those questions first. The speed of light in a vacuum is 299,792.458 km per second – just shy of a nice round 300,000km/s figure. That is pretty nippy. The Sun is 150 million km away from Earth and light takes just eight minutes and 20 seconds to travel that far.
He needed to use ever-larger amounts of additional energy to make ever-smaller differences to the speed
Can any of our own creations compete in a race with light? One of the fastest human-made objects ever built, the New Horizons space probe, passed by Pluto and Charon in July 2015. It has reached a speed relative to the Earth of just over 16km/s, well below 300,000km/s.
However, we have made tiny particles travel much faster than that. In the early 1960s, William Bertozzi at the Massachusetts Institute of Technology experimented with accelerating electrons at greater and greater velocities.
Because electrons have a charge that is negative, it is possible to propel – or rather, repel – them by applying the same negative charge to a material. The more energy applied, the faster the electrons will be accelerated.
Still, light sometimes appears to travel more slowly than we might expect. Although internet technicians like to talk about communications travelling at "the speed of light" through optical fibres, light actually travels around 40% slower through the glass of those fibres than it would through a vacuum.
In reality, the photons are still travelling at 300,000km/s, but they are encountering a kind of interference caused by other photons being released from the glass atoms as the main light wave travels past. It is a tricky concept to get your head around, but it is worth noting.
Similarly, special experiments with individual photons have managed to slow them down by altering their shape.
Optical fibers carry information (Credit: Cultura Creative (RF)/Alamy Stock Photo)
Optical fibers carry information (Credit: Cultura Creative (RF)/Alamy Stock Photo)
Still, for the most part it is fair to say that light travels at 300,000km/s. We really have not observed or created anything that can go quite that quickly, or indeed more quickly. There are a few special cases, mentioned below, but before those, let's tackle that other question. Why is it so important that this speed of light rule be so strict?
Even though the distance has increased, Einstein's theories insist that the light is still travelling at the same speed
The answer lies, as so often in physics, with a man named Albert Einstein. His theory of special relativity explores many of the consequences of these universal speed limits.
One of the important elements in the theory is the idea that the speed of light is a constant. No matter where you are or how fast you are travelling, light always travels at the same speed.
But that creates some conceptual problems.