- 3175 - RELATIVITY - can this theory be replaced? The discovery of gravitational waves in 2015 was a decisive victory, but, like its predecessors, it too might be about to fall. That's because it is fundamentally incompatible with Quantum Theory and that does not reconcile with the Theory of Relativity.
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- Earliest humans thought Earth was at the center of the solar system and that idea stood for over 1,000 years. Then Copernicus came along and said that the whole system would be a lot simpler if we are just another planet orbiting the sun. Despite much initial opposition, the old geocentric picture eventually buckled under the weight of evidence from the newly invented telescope.
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- Then Newton came along to explain that gravity is why the planets orbit the sun. He said all objects with mass have a gravitational attraction towards each other. According to his ideas we orbit the sun because it is pulling on us, the moon orbits Earth because we are pulling on it.
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- Newton ruled for two-and-a-half centuries before Albert Einstein turned up in 1915 to offer his explanation, the “General Theory of Relativity“. This new picture neatly explained inconsistencies in Mercury's orbit, and was famously confirmed by observations of a solar eclipse off the coast of Africa in 1919.
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- Instead of a pull, Einstein saw gravity as the result of curved space. He said that all objects in the universe sit in a smooth, four-dimensional fabric called space-time.
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- Massive objects such as the sun warp the space-time around them, and so Earth's orbit is simply the result of our planet following this curvature. To us that looks like a Newtonian gravitational pull but it is simply cured space.
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- In the quantum world single particles can be in two places at once. Only by making an observation do we force it to 'choose'. Before an observation we can only assign “probabilities” to the likely outcomes.
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- Such a picture cannot be reconciled with a smooth, continuous fabric of space-time. A gravitational field cannot be in two places at once. According to Einstein, space-time is warped by matter and energy, but quantum physics says matter and energy exist in multiple states simultaneously, They can be both here and over there.
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- Try and use general relativity and quantum theory together, and it doesn't work. Above a certain energy, you get probabilities that are larger than one, larger that 100%. One is the highest probability possible, it means an outcome is certain. You can't be more certain than certain.
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- Equally, calculations sometimes give you the answer infinity, which has no real physical meaning. The two theories are therefore mathematically inconsistent.
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- Physicists are searching for a new theory of “quantum gravity“. The most famous is “string theory“. It's the idea that sub-atomic particles such as electrons and quarks are made from tiny vibrating strings. Just as you can play strings on a musical instrument to create different notes, string theorists argue that different combinations of strings create different particles.
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- The attraction of the theory is that it can reconcile general relativity and quantum physics. However, the strings have to vibrate across eleven dimensions, seven more than the four in Einstein's space-time fabric.
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- As yet there is no experimental evidence that these extra dimensions really exist. It might be interesting mathematics, but whether it describes the space-time in which we live.
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- Partly inspired by string theory's perceived failings, other physicists have turned to an alternative called “Loop Quantum Gravity” (LQG).
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- Physicists can get the two theories to play nicely if they do away with one of the central tenets of general relativity, that space-time is a smooth, continuous fabric. Instead space-time is made up of a series of interwoven loops and that it has structure at the smallest size scales.
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- This is a bit like a length of cloth. At first glance it looks like one smooth fabric. Look closely, however, and you'll see it is really made of a network of stitches. Alternatively, think of it like a photograph on a computer screen: Zoom in, and you'll see it is really made of individual pixels.
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- The trouble is that when LQG physicists say small, they mean really small. These defects in space-time would only be apparent on the level of the “Planck scale“, around a trillionth of a trillionth of a trillionth of a meter.
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- That's so tiny that there would be more loops in a cubic centimeter of space than cubic centimeters in the entire observable universe.
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- Light arriving here from the furthest reaches of the universe has traveled through billions of light years of space-time along the way. While the effect of each space-time defect would be tiny, over those distances interactions with multiple defects might well add up to a potentially observable effect.
- Astronomers have been using light from far-off Gamma Ray Bursts to look for evidence in support of LQG. These cosmic flashes are the result of massive stars collapsing at the ends of their lives.
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- There is something about these distant detonations we currently cannot explain. Their spectrum has a systematic distortion to it, but no one knows if that is something that happens on the way here or if it's something to do with the source of the bursts themselves.
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- Space-time doesn't exist independently of the objects in it. Space-time is defined by the way objects interact. That would make space-time an artifact of the quantum world itself, not something to be combined with it.
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- This theory, called “modular space-time” might help solve another long-standing problem in theoretical physics regarding something called “locality“, and a notorious phenomenon in quantum physics called “entanglement“.
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- Physicists can set up a situation whereby they bring two particles together and link their quantum properties. They then separate them by a large distance and find they are still linked. Change the properties of one and the other will change instantly, as if information has traveled from one to the other faster than the speed of light in direct violation of relativity.
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- Einstein was so perturbed by this phenomenon that he called it 'spooky action at a distance'.
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- Modular space-time theory can accommodate such behavior by redefining what it means to be separated. If space-time emerges from the quantum world, then being closer in a quantum sense is more fundamental than being close in a physical sense.
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- Albert Einstein dispensed with the Newtonian picture of gravity as a force, replacing it with space-time.
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- We sit in space, we travel through time, and if something changes in our understanding of space-time this will impact not only on our understanding of gravity, but of quantum theory in general.
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- All our present devices only work because of quantum theory. If we understand the quantum structure of space-time better that will have an impact on future technologies.
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- 2902 - RELATIVITY - measurements made in 2020? At the heart of every white dwarf star, which is the dense stellar object that remains after a star has burned away its fuel reserve of gases as it nears the end of its life cycle, lies a “quantum conundrum‘.
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----------------------------- Other reviews available:
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- 2838 - RELATIVITY - as scientists explain it? The Universe is hard to explain. Here are our best minds trying with their favorite theories. God provides a simpler explanation. It is just the way he made things. Yet, we keep trying to understand how he did it. Here are the scientists that have they best ideas to date, 2020. We keep trying to understand how we got here? It ain’t easy?
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- 2701 - RELATIVITY - as best I can explain it? - Relativity tells us that an object in motion changes “Time and Space“. Mass also changes time and space with its gravity. And, motion increases Mass at the same time is slows Time and shortens Space. In this review you will learn how Relativity works and how to derive Einstein’s calculations of its effect using the Pythagorean Theorem and simple algebra. Why didn’t I think of that?
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- 2417 - RELATIVITY - best I can explain it. - Relativity starts with a very simple concept. It starts with all motion being relative. Space and Time require a reference frame in order to be measured. There is no dimension in space or interval in time without it being in reference to something else. All observers see things from different space-time perspectives.
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- 2302 - Before Einstein’s time mass, or matter, and energy were totally different things. In 1905 Einstein changed this world of physics and astronomy using one very, very simple idea, the laws of nature are the same for all observers regardless of their position or their relative motion. Here is how he came up with this idea.
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- 2302 - Before Einstein’s time mass, or matter, and energy were totally different things. In 1905 Einstein changed this world of physics and astronomy using one very, very simple idea, the laws of nature are the same for all observers regardless of their position or their relative motion. Here is how he came up with this idea.
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- 2269 - Relativity - Light has no time. Time has stopped for light. In fact, time does not move for all the electromagnetic forces and gravity when they’re traveling at light speed. If light or gravity had mass, or inertia, it would be infinitely large at light speeds. Therefore, it would take infinite energy to move it. Light has no mass.
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- 2103 - Not what time you think? A moving person will experience shorter time durations that a stationary person?
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- 2054 - Relativity explained. It starts with all motion is relative. Time and space are a reference frame.
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- 1812 - Blackholes and relativity.
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- 1803 - Blackholes test Relativity.
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- 1791 - The consequences of Relativity?
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- May 27, 2021 RELATIVITY - can this theory be replaced? 3175
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