Posts Tagged ‘relativity’

BY LI YEN, EPOCH TIMES

France Córdova, National Science Foundation director, said in a statement: “Black holes have sparked imaginations for decades. They have exotic properties and are mysterious to us.”

In fact, the mysterious black holes, dubbed as “monsters” by scientists, are not empty space, according to NASA. They are instead, as presented in Albert Einstein’s theory of general relativity, made up of “a great amount of matter packed into a very small area,” mostly formed from “the remnants of a large star that dies in a supernova explosion.”

Einstein predicted the existence of massive and dense black holes in the universe, where the gravitational fields are so strong that even light can’t escape.

The German-born American physicist, widely regarded as a genius today, made known this theory to the world more than a century ago on Nov. 25, 1915, at the Prussian Academy of Sciences.

“About a hundred years ago, Albert Einstein gave us a new description of the force of gravity, in which gravity exerts its influence through warps and curves in the fabric of space and time,” Brian Greene, a physicist at Columbia University, said in a video for the World Science.

After Einstein’s death, the scientific community discovered that black holes do exist, and there are countless such black holes spreading throughout the universe.

On April 10, the genius’s century-old theory of general relativity was further reaffirmed—the existence of the gravitational and light-sucking cosmic objects was reported to be true.

“Today, general relativity has passed another crucial test, this one spanning from horizons to the stars,” Avery Broderick, Event Horizon Telescope (EHT) team member of the University of Waterloo and the Perimeter Institute for Theoretical Physics in Canada, said during a press conference in Washington, D.C.

“You can see the ring Einstein’s relativity predicts,” Vincent Fish, a research scientist at MIT’s Haystack Observatory in Westford, and also one of the 200 scientists who was involved in the project, told the Boston Herald. “You know exactly how big that ring should be. This was the first opportunity to test that hypothesis.”

Dimitrios Psaltis, Professor of Astronomy and Physics at the University of Arizona, and EHT project scientist, said in a press release: “The Event Horizon Telescope allows us for the very first time to test the predictions of Einstein’s General Theory of Relativity around supermassive black holes in the centers of galaxies. The predicted size and shape of the shadow theory match our observations remarkably well, increasing our confidence in this century-old theory.”

“If immersed in a bright region, like a disc of glowing gas, we expect a black hole to create a dark region similar to a shadow—something predicted by Einstein’s general relativity that we’ve never seen before,” Heino Falcke of Radboud University, the Netherlands, chair of the EHT Science Council, said.

Some Refute Einstein’s Theory

Despite the theory that shot Einstein to fame, some scientists have said the theory doesn’t explain everything, and requires revision.

Speaking about gravity, Austrian physicist Andrea Ghez, who led a 20-year-long black hole experiment, told Express News: “You can hark back to the days of Newton—who had the previous best description of gravity—and at some point we realized we had to move beyond Newton, to get a more complete vision.”

Ghez added: “As we explore these more and more extreme conditions we see that there is something missing.

“the closer you get to the heart of the galaxy, the shorter the time scales become.”

In terms of light, central to Einstein’s Theory of General Relativity is that the speed of light is constant everywhere.

One counter theory by researchers suggests that the speed of light is varied, and that light traveled faster in the wake of the Big Bang—a significant blow to Einstein’s theory.

“The idea that the speed of light could be variable was radical when first proposed, but with a numerical prediction, it becomes something physicists can actually test. If true, it would mean that the laws of nature were not always the same as they are today,” cosmologist and theoretical physicist João Magueijo told news.com.au.

Location of the Historic Finding

The black hole that was discovered resides at the heart of a huge galaxy known as Messier 87 or M87, near the Virgo galaxy cluster, 55 million light years from Earth.

The first snapshot of the black hole was captured by scientists using a global network of eight linked telescopes that were stationed over five continents in April 2017 for a week-long observation of black holes, according to Event Horizon Telescope.

“This is an extraordinary scientific feat accomplished by a team of more than 200 researchers,” said Sheperd Doeleman, director of the EHT Collaboration.

The enormous black hole captured in the image is predicted to have a mass 6.5 billion times bigger than our sun. Researchers believe it may be the biggest black hole that can be viewed from Earth.

“M87’s huge black hole mass makes it really a monster, even by supermassive black hole standards,” Sera Markoff, an astrophysicist at the University of Amsterdam, told The Verge. “You’re basically looking at a supermassive black hole that’s almost the size of our entire Solar System.”

https://www.theepochtimes.com/historic-image-of-black-hole-said-to-prove-einsteins-theory-of-relativity_2876829.html

By Jeffrey Bennett

It has been exactly 100 years since Albert Einstein presented his theory of general relativity to an audience of scientists on November 25, 1915. While virtually everyone has heard of Einstein and his theory, very few people have any idea of what the theory actually is.

This is a shame, not only because there is a great public thirst for understanding of it, but also because relativity is important, for at least four major reasons.

General relativity provides our modern understanding of space, time and gravity — which means it’s crucial to almost everything we do in physics and astronomy. For example, you cannot understand black holes, the expansion of the universe or the Big Bang without first understanding the basic ideas of relativity. Though few people realize it, Einstein’s famous equation E = mc2 is actually part of the theory of relativity, which means that relativity also explains how the sun shines and how nuclear power works.

A second reason everyone should know about relativity lies in the way it changes our perception of reality. Relativity tells us that our ordinary perceptions of time and space are not universally valid. Instead, space and time are intertwined as four-dimensional space-time.

In our ordinary lives, we perceive only three dimensions—length, width and depth—and we assume that this perception reflects reality. However, in space-time, the four directions of possible motion are length, width, depth and time. (Note that time is not “the” fourth dimension; it is simply one of the four.)

Although we cannot picture all four dimensions of space-time at once, we can imagine what things would look like if we could. In addition to the three spatial dimensions of space-time that we ordinarily see, every object would be stretched out through time. Objects that we see as three-dimensional in our ordinary lives would appear as four-dimensional objects in space-time. If we could see in four dimensions, we could look through time just as easily as we look to our left or right. If we looked at a person, we could see every event in that person’s life. If we wondered what really happened during some historical event, we’d simply look to find the answer.

To see why this is so revolutionary, imagine that you met someone today who deeply believed that Earth is the center of the universe. You would probably feel sorry for this person, knowing that his or her entire world view is based on an idea disproven more than 400 years ago.

Now imagine that you met someone who still believed that time and space are independent and absolute — which, of course, describes almost everyone — even though we’ve known that’s not the case for a century now. Shouldn’t we feel equally sorry for all who hold this modern misconception?

It seems especially unfortunate once you realize that the ideas of relativity are not particularly difficult to understand. Indeed, I believe we could begin teaching relativity in elementary school in much the same way that we teach young children about the existence of atoms, even though few will ever study quantum mechanics.

My third reason for believing relativity is important lies in what Einstein’s discovery tells us about human potential. The science of relativity may seem disconnected from most other human endeavors, but I believe Einstein himself proved otherwise. Throughout his life, Einstein argued eloquently for human rights, human dignity and a world of peace and shared prosperity. His belief in underlying human goodness is all the more striking when you consider that he lived through both World Wars, that he was driven out of Germany by the rise of the Nazis, that he witnessed the Holocaust that wiped out more than six million of his fellow Jews, and that he saw his own discoveries put to use in atomic bombs.

No one can say for sure how he maintained his optimism in the face of such tragedies, but I see a connection to his discovery of relativity. Einstein surely recognized that a theory that so challenged our perceptions of reality might have been dismissed out of hand at other times in history, but that we now live in a time when, thanks to the process that we call science, the abundant evidence for relativity allowed for its acceptance.

This willingness to make judgments based on evidence shows that we are growing up as a species. We have not yet reached the point where we always show the same willingness in all our other endeavors, but the fact that we’ve done it for science suggests we have the potential.

Finally, on a philosophical level, relativity is profound. Only about a month before his death in 1955, Einstein wrote: “Death signifies nothing … the distinction between past, present and future is only a stubbornly persistent illusion.” As this suggests, relativity raises interesting questions about what the passage of time really means.

Because these are philosophical questions, they do not have definitive answers, and you will have to decide for yourself what these questions mean to you. But I believe that one thing is clear. Einstein showed that even though space and time can independently differ for different observers, the four-dimensional space-time reality is the same for everyone.

This implies that events in space-time have a permanence to them that cannot be taken away. Once an event occurs, in essence it becomes part of the fabric of our universe. Every human life is a series of events, and this means that when we put them all together, each of us is creating our own, indelible mark on the universe. Perhaps if everyone understood that, we might all be a little more careful to make sure that the mark we leave is one that we are proud of.

So there you have it. Relativity is necessary to comprehend the universe as we know it, it helps us understand the potential we all share when we put our brains to work for the common good, and if we all understood it we might treat each other a little more kindly.

http://www.cnn.com/2015/11/25/opinions/bennett-einstein-theory-of-relativity/index.html