Tag: gravity

Is This Geometric Structure The Theory Of Everything?

For 100 years, scientists have been searching for the “Theory of Everything”, the elusive link between the physics of Quantum Mechanics and General Relativity. A team of researchers believe they may have the key, and it all lies in a geometrical design.

Garrett Lisi’s work in particle physics led him to find patterns in the geometry that led him to discover an 8-dimensional crystalline structure called the E8 Lie Group. He used this to predict the existence of particles that he believes account for the force of gravity.

Klee Irwin and the Quantum Gravity Research team have taken this and constructed a theory about the nature of reality itself all the way down to the plank length, where reality breaks down into pixellated tetrahedrons that through emergence theory has created a universal consciousness.

NASA Is Planning To Make Water And Oxygen On The Moon And Mars By 2020

NASA astronaut Kate Rubins works with a Nitrogen/Oxygen Recharge System tank aboard the International Space Station.

NASA is forging ahead with plans to make water, oxygen, and hydrogen on the surface of the Moon and Mars.

If we ever want to colonize other planets, it is vital that we find a way of extracting these vital gases and liquids from moons and planets, rather than transporting them from Earth.

The current plan is to land a rover on the Moon in 2018 that will try to extract hydrogen, water, and oxygen — and then hopefully, Curiosity’s successor will try to convert the carbon dioxide in the atmosphere into oxygen in 2020 when it lands on Mars.

In 2018, NASA hopes to put a rover on the Moon that will carry the RESOLVE (Regolith and Environment Science and Oxygen & Lunar Volatile Extraction) science payload.

RESOLVE will contain the various tools necessary to carry out in-situ resource utilization (ISRU).




Basically, RESOLVE will sift through the Moon’s regolith (loose surface soil) and heat them up, looking for traces of hydrogen and oxygen, which can then be combined to make water.

There is also some evidence that there’s water ice on the surface of the Moon — RESOLVE will find out for certain by heating the soil and seeing of water vapor emerges.

A similar payload would be attached to Curiosity’s successor, which is currently being specced out by NASA and will hopefully launch in 2020.

This second IRSU experiment will probably suck in carbon dioxide from the Martian atmosphere, filter out the dust, and then process the CO2 into oxygen.

If either tech demonstration works as planned, future missions might include large-scale ISRU devices that are capable of producing significant amounts of hydrogen, oxygen, and water on the Moon or Mars.

This would probably be the most important advance since we first landed on the Moon in the ’60s. Basically, as it stands, space travel needs lots of hydrogen and oxygen and water.

Water has the unfortunate characteristic of being both heavy and incompressible, meaning it’s very difficult and expensive to lift large amounts of it into space (gravity can be really annoying sometimes).

Likewise, unless we come up with some other way of powering our spacecraft, it’s infeasible to carry the rocket fuel that we’d need for exploration from Earth.

In short, if we want to colonize space, we really, really need some kind of base outside of the Earth’s atmosphere, preferably on the Moon — but Mars would be good, too.

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Pass it on: Popular Science

Astrophysicists Spotted A ‘Galaxy Without Dark Matter’

An unusual galaxy far, far away is stumping astronomers not because of what’s there, but because of what’s missing.

About 65 million light-years away, the galaxy called NGC1052-DF2 is dim and diffuse, coming in at about one two-hundredths the mass of our Milky Way.

Normally, not all of a galaxy’s mass is visible. In addition to a mix of ordinary matter—like stars and planets and manatees—galaxies are expected to contain dark matter, an invisible substance that makes up most of the mass in the universe.

Although we can’t directly observe it, we know dark matter is there because we can see how its gravity affects ordinary matter.

Based on the ratio in other galaxies, an isolated galaxy like NGC1052-DF2 should have about a hundred times more dark matter than ordinary matter. But this one appears to have … almost none, scientists report today in Nature.




How did scientists figure that out?

Using a cluster of lenses called the Dragonfly Telephoto Array, a team led by Yale University’s Pieter van Dokkum took a really close look at NGC1052-DF2.

By tracking the motion of 10 embedded star clusters, the team could determine how much mass is tucked into the galaxy. And surprisingly, it’s about the same amount of mass they’d expect to see from the galaxy’s stars alone.

We really thought dark matter was not just an optional component of galaxies,” van Dokkum says, noting that the team has found several other similarly perplexing galaxies to scrutinize.

Why is this observation important?

One strange observation doesn’t necessarily break a theory. But finding a galaxy that’s more or less devoid of dark matter certainly suggests a few tantalizing things. First, it really challenges ideas about how galaxies form.

In modern galaxy formation theory, our understanding is that galaxies form in a dark matter halo,” says Stanford University’s Risa Wechsler.

There’s a pretty tight relationship between the amount of stars that formed and the dark matter there, at least when the galaxy formed.

In other words, no dark matter, no galaxy.

In theories proposing alternatives to dark matter, such as modifications to our understanding of gravity, whatever is mimicking the dark matter signature is not something that can be turned on or off—it should always be there.

So, van Dokkum says, “by not detecting the dark matter, we actually prove it’s real.”

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Pass it on: New Scientist

The Universe May Be Expanding Faster Than We Thought. Does It Mean Something?

At the beginning of time, all the matter in the universe was compressed into an infinitesimally small point. That tiny speck of everything then exploded and formed the universe.

In some sense, it’s still exploding, expanding at an accelerating rate.

In the past, scientists have looked to the radiation left behind from the Big Bang — its smoking gun — to calculate what the rate of the expanding universe ought to be today.

But new evidence, soon to be published in The Astrophysical Journal, suggests these estimates may be wrong, or at least incomplete.

New observations from the Hubble Space Telescope have indicated that the universe may be expanding 5 to 9 percent faster than predicted by the Big Bang.




But how?

Using the Hubble, scientists from across the US were able to painstakingly measure the distance to stars and supernovae in many galaxies.

They then used this data to refine what’s known as the “Hubble constant,” the rate by which the universe expands, as measured by direct observations.

But when this new “Hubble constant” was compared with the estimates from the Big Bang inferences, the numbers just didn’t match.

You start at two ends, and you expect to meet in the middle if all of your drawings are right and your measurements are right,” Adam Riess, the Nobel laureate at the Space Telescope Science Institute and Johns Hopkins University, who led the project, explained Thursday in a statement.

“But now the ends are not quite meeting in the middle and we want to know why.”

Add this to the long list of questions physicists still have about the universe

The prediction based on the Big Bang “should match our measurement,” Lucas Macri, a Texas A&M physicist and one of the study’s co-authors, tells me.

“If they don’t … there must be a physical reason why these two things are not agreeing.”

So what accounts for the discrepancy?

Either there’s something about the Big Bang that previous estimates have not accounted for or there are factors that come into play after the Big Bang that scientist don’t yet understand.

Macri highlights four possible explanations.

The first is related to the Big Bang.

)We’re seeing evidence of a previously unknown subatomic particle that was abundant right after the Big Bang (a.k.a. ‘dark radiation’),” he says.

If you change the assumptions about what was in the primordial soup, things will have shifted a bit.

The other possibilities are related to “dark energy” and “dark matter,” the substances that make up most of the universe yet can’t be directly observed.

2) Dark energy — the mysterious force that opposes gravity and is causing the universe to accelerate — “is growing in strength and ‘pushing’ galaxies apart faster than it did before,” he says.

3) Dark matter — matter that we can’t see but that is theorized to exist and make up most of the matter in the universe — “is even weirder than we thought.

Or it could not so simply be:

4)Our theory of gravity is incomplete.”

He also mentions that their results aren’t set in stone. “There’s one chance in 1,000 that we got this measurement by accident,” he says.

Physics requires a one in 4 million chance for results to be considered truth. More observations will need to be made.

Macri says he and other researchers will know more soon, especially if they get to use the James Webb Space Telescope, which will replace Hubble in the year 2018.

The James Webb will be able to look much deeper into space than Hubble and can refine the Hubble constant estimate further.

A modest amount of time with James Webb will allow us to make a very significant improvement on our measurement,” Macri says.

Overall, he says, it’s important to know the exact rate of universal expansion because it will yield a more accurate age of the universe.

To get the age of the universe you need to have the Hubble constant,” he says. Right now the uncertainty of their estimate is 2.4 percent, which is the best yet. But not good enough.

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Pass it on: New Scientist

Scientists Detect Gravitational Waves Caused By Two Black Holes Colliding 1.3 Billion Years Ago In Historic Experiment Proving The Theory Of General Relativity

Professor Stephen Hawking said the detection marked a moment in scientific history.

Gravitational waves provide a completely new way at looking at the universe,” he told the BBC. ‘The ability to detect them has the potential to revolutionize astronomy.

This discovery is the first detection of a black hole binary system and the first observation of black holes merging.

The gravitational wave found in this study is believed to be the product of a collision between two massive black holes, 1.3 billion light years away — a remarkably extreme event that has not been observed until now.

The colliding black holes that produced these gravitational waves created a violent storm in the fabric of space and time, a storm in which time speeded up, and slowed down, and sped up again, a storm in which the shape of space was bent in this way and that way,” Caltech physicist Kip Thorne said.

Based on the physics of this particular event, LIGO scientists estimate that the two black holes in this event were about 29 and 36 times the mass of the sun, and that the event took place 1.3 billion years ago.




About three times the mass of the sun was converted into gravitational waves in a fraction of a second – with a peak power output about 50 times that of the whole visible universe. LIGO observed these gravitational waves.

The researchers detected the signal with two Laser Interferometer Gravitational-wave Observatories (LIGO) in Louisiana and Washington.

These are twin detectors carefully constructed to detect incredibly tiny vibrations from passing gravitational waves.

Once the researchers spotted a gravitational signal, they converted it into audio waves and listened to the sound of two black holes spiraling together, then merging into a larger single black hole.

We’re actually hearing them go thump in the night,” says Matthew Evans, an assistant professor of physics at MIT.

According to General Relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitational waves, causing them to gradually approach each other over billions of years, and then much more quickly in the final minutes.

During the final fraction of a second, the two black holes collide into each other at nearly one-half the speed of light and form a single more massive black hole, converting a portion of the combined black holes’ mass to energy according to Einstein’s formula E=mc2.

This energy is emitted as a final strong burst of gravitational radiation.

These waves then rippled through the universe, effectively warping the fabric of space-time, before passing through Earth more than a billion years later as faint traces of their former, violent origins.

This is the holy grail of science,” said Rochester Institute of Technology astrophysicist Carlos Lousto.

The last time anything like this happened was in 1888 when Heinrich Hertz detected the radio waves that had been predicted by James Clerk Maxwell’s field-equations of electromagnetism in 1865,” added Durham University physicist Tom McLeish.

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Pass it on: New Scientist

The Mystery of Gravity

Of all the fundamental forces, Gravity is the most fundamental to our experience on this planet. We’ve always known that what goes up must come down, though we never really knew why.

Aristotle believed that objects fell toward Earth because they wanted to move toward their “natural state”. Because Aristotle was wrong about everything.

Galileo proved that objects fall at the same rate regardless of how heavy they are, and that they fall at a constant acceleration of 9.8 meters per second squared.

Sir Isaac Newton was the first to grasp that gravity was an attractive force between objects with mass and was able to devise the equations around gravity that we still use today.

Then Einstein redefined our understanding of gravity as a curvature in space-time caused by objects with mass.

Now, a common misconception is that gravity doesn’t work in outer space because we always see astronauts in zero gravity.

And if you’re anything like me, you grew up seeing this and just thought that the further you get away from the earth’s surface, the less gravity affects you, and that’s why astronauts get to float around all cool up there like that.

But that’s not how it works. That’s not how any of this works.

The reason these astronauts are floating is because they’re in orbit around the planet. And orbit is basically a state of always falling.

So being on the ISS is basically like constantly being in an elevator that’s plummeting toward the ground.

Some people, myself included, originally mistook the higgs boson as the force carrier for gravity because when you look at the standard model of particle physics, the other three fundamental forces all have force carrier particles called bosons.

Specifically, photons, gluons, and w and z bosons.

But the higgs boson is the force carrier of the higgs mechanism, which is a totally different thing. So I was wrong. I know, go figure.

But because all the other forces have force carrier particles, it was assumed that gravity would as well, which scientists called the graviton.

The graviton, if it exists, would be massless, because it works over unlimited distances, and would be a spin-2 boson, also known as a tensor boson.

It’s been theorized a massless spin-2 field would give rise to a force indistinguishable from gravitation, because a massless spin-2 field would couple to the stress–energy tensor in the same way that gravitational interactions do.

Gravitons also pose a problem with a mathematical issue called renormalization.

These issues have spurred some researchers to look for answers outside of quantum field theory like in string theory.

Some have tried to merge the supersymmetry found in string theory with general relativity in what they call Supergravity.

In the 80’s a theory called Modified Newtonian Dynamics, or MOND was introduced which tries to explain the movement of stars in galaxies without the use of Dark Matter.

Later, in 2004, MOND got modified further to create tensor-vector-scalar gravity which relies on a relativistic lagrangian density that maintains the law of conservation of energy.

Another popular idea is Erik Verlinde’s entropic gravity, which argues that gravity is an emergent force that arises from entropy itself and not a fundamental force at all.

And who can forget the chameleon particle theory, which has a variable effective mass that is an increasing function of the ambient energy density, meaning the particle’s mass changes to cause different effects on the particles around it.

So strangely, the first force we were aware of has become the last to be fully understood. And the one that, if we do ever fully understand it, would unlock the secrets of the universe.

LINKS:

Stress-Energy tensor

Newton’s Cannonball

Vertasium

VSauce

Gravity 3d animation

Higgs field animation

https://en.wikipedia.org/wiki/Gravity#Alternative_theories

https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics

https://en.wikipedia.org/wiki/Entropic_gravity

https://en.wikipedia.org/wiki/Chameleon_particle