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Why physicists are determined to prove Galileo and Einstein wrong | Live Science

In the 17th century, famed astronomer and physicist Galileo Galilei is said to have climbed to the top of the Tower of Pisa and dropped two different-sized cannonballs. He was trying to demonstrate his theory — which Albert Einstein later updated and added to his theory of relativity — that objects fall at the same rate regardless of their size.

Now, after spending two years dropping two objects of different mass into a free fall in a satellite, a group of scientists has concluded that Galileo and Einstein were right: The objects fell at a rate that was within two-trillionths of a percent of each other, according to a new study.

This effect has been confirmed time and time again, as has Einstein’s theory of relativity — yet scientists still aren’t convinced that there isn’t some kind of exception somewhere. “Scientists have always had a difficult time actually accepting that nature should behave that way,” said senior author Peter Wolf, research director at the French National Center for Scientific Research’s Paris Observatory.

That’s because there are still inconsistencies in scientists’ understanding of the universe.

“Quantum mechanics and general relativity, which are the two basic theories all of physics is built on today …are still not unified,” Wolf told Live Science. What’s more, although scientific theory says the universe is made up mostly of dark matter and dark energy, experiments have failed to detect these mysterious substances.

“So, if we live in a world where there’s dark matter around that we can’t see, that might have an influence on the motion of [objects],” Wolf said. That influence would be “a very tiny one,” but it would be there nonetheless.

So, if scientists see test objects fall at different rates, that “might be an indication that we’re actually looking at the effect of dark matter,” he added.

Wolf and an international group of researchers — including scientists from France’s National Center for Space Studies and the European Space Agency — set out to test Einstein and Galileo’s foundational idea that no matter where you do an experiment, no matter how you orient it and what velocity you’re moving at through space, the objects will fall at the same rate.

The researchers put two cylindrical objects — one made of titanium and the other platinum — inside each other and loaded them onto a satellite. The orbiting satellite was naturally “falling” because there were no forces acting on it, Wolf said.

They suspended the cylinders within an electromagnetic field and dropped the objects for 100 to 200 hours at a time.

From the forces the researchers needed to apply to keep the cylinders in place inside the satellite, the team deduced how the cylinders fell and the rate at which they fell, Wolf said.

And, sure enough, the team found that the two objects fell at almost exactly the same rate, within two-trillionths of a percent of each other. That suggested Galileo was correct. What’s more, they dropped the objects at different times during the two-year experiment and got the same result, suggesting Einstein’s theory of relativity was also correct.

Their test was an order of magnitude more sensitive than previous tests. Even so, the researchers have published only 10% of the data from the experiment, and they hope to do further analysis of the rest.

Not satisfied with this mind-boggling level of precision, scientists have put together several new proposals to do similar experiments with two orders of magnitude greater sensitivity, Wolf said.

Also, some physicists want to conduct similar experiments at the tiniest scale, with individual atoms of different types, such as rubidium and potassium, he added.

The findings were published Dec. 2 in the journal Physical Review Letters.

Source: Why physicists are determined to prove Galileo and Einstein wrong | Live Science






 

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ASTROPHYSICS

‘God Plays Dice with the Universe,’ Einstein Writes in Letter About His Qualms with Quantum Theory

‘God Plays Dice with the Universe,’ Einstein Writes in Letter About His Qualms with Quantum Theory

By Mindy Weisberger, Senior Writer | June 12, 2019

In a letter that Albert Einstein wrote in 1945, the famous physicist sketched two diagrams demonstrating a novel approach to the thought experiment called the Einstein-Podolsky-Rosen (EPR) paradox.

Three letters written by Albert Einstein in 1945 are up for auction and offer an intriguing glimpse into the renowned physicist’s criticisms of how scientists were interpreting physics at the quantum level.

The letters, which were addressed to Caltech theoretical physicist Paul Epstein, describe Einstein’s qualms about quantum theory, which he called “incomplete” in one letter.

Another letter details the thought experiment that led to a quantum concept known as “spooky action at a distance” — when separated particles behave as if they were linked. The letters — eight pages of German writing and hand-drawn diagrams — will hit the auction block at Christie’s in New York today (June 12) at 2 p.m. ET, as part of the “Fine Printed Books and Manuscripts Including Americana” auction.

Einstein’s words in the letters demonstrate his fraught relationship with quantum physics, or the theories that describe the world of the very small (atoms and the subatomic particles inside them). For decades, he famously clashed with physicist Niels Bohr, whose views on the workings of the quantum world stated that particles behave differently when they are observed.

This introduced a fundamental element of uncertainty into the behavior of quantum particles; Einstein soundly rejected this perspective. Instead, Einstein argued that the rules for even tiny particles must be consistent whether the particles were observed or not.

“God tirelessly plays dice”

Einstein described his “private opinion” of quantum physics in one of the 1945 letters by referencing a phrase that he had already made famous: “God does not play dice with the universe.” In the letter, he wrote: “God tirelessly plays dice under laws which he has himself prescribed.” This variation clarified his argument that quantum particles must adhere to certain rules that don’t change randomly, and that the quantum world required better explanations for particle behavior, according to the item description.

While Einstein admitted in the letter that quantum theory in its present form was “a highly successful experiment,” he added that it had been undertaken “with inadequate means.”

In another letter written on Nov. 8, 1945, Einstein maps the origins of his thought experiment behind quantum entanglement, using text and diagrams to explain how he first imagined it. Einstein presented this idea in a paper published in 1935; the concept — co-authored with Boris Podolsky and Nathan Rosen — became known as the Einstein-Podolsky-Rosen (EPR) paradox, or spooky action at a distance, according to the American Physical Society.

Einstein and his colleagues meant for this paradox to demonstrate inherent flaws in perceptions of the quantum world. When Epstein responded to Einstein’s Nov. 8 letter with skepticism, Einstein reworked the EPR paradox, sending another version of the thought experiment in a letter dated Nov. 28, 1945.

He concluded the letter by reiterating his long-held criticism of the idea that the quantum realm couldn’t be described definitively, saying “it is this view against which my instinct revolts.”

However, recent experiments have suggested that despite Einstein’s protestations, the behavior of particles at the quantum level is likely influenced by randomness after all.

Together, the letters are expected to fetch more than $200,000 at the auction, according to the Christie’s website.

Source: ‘God Plays Dice with the Universe,’ Einstein Writes in Letter About His Qualms with Quantum Theory






 

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