Gravitational Waves in the Space-Time Continuum
Einstein's Theories of Relativity
Einstein has two theories of relativity. The first is The Theory of Special Relativity (1905). This is a theory of mechanics that correctly describes the motions of objects moving near the speed of light. This theory predicts that mass increases with velocity. The equation is E=MC^2 or Energy = Mass × Speed of Light ^2.
In 1916, Einstein proposed the Theory of General Relativity, which generalized his Theory of Special Relativity and had the first predictions of gravitational waves. It implied a few things.
Space-Time is a 4-Dimensional continuum.
Principle of equivalence of gravitational and inertial mass.
This suggests that Mass-Energy distorts the fabric of space-time in a predictable way (gravitational waves). It also implies
Strong gravitational force makes time slow down.
Light is altered by gravity
Gravity in strong gravitational fields will no longer obey Newton's Inverse-Square Law.
What is Newton's Inverse-Square Law?
Newton's Inverse-Square Law suggests that the force of gravity between any two objects is inversely proportional to the square of the separation distance between the two centers.
Stephen Hawking's Theory of Everything
Stephen Hawking's Theory of Everything is the solution to Einstein's equation in his Theory of General Relativity. It says that the mass density of the universe exceeds the critical density.
Critical Density: amount of mass needed to make a universe adopt a flat geometry.
This theory states that when the universe gets too big it will crash back into its center in a "Big Crunch" creating giant black hole. The energy from this "Big Crunch" will rebound and create a new "Big Bang".
Big Crunch: hypothetical scenario for the end of the known universe. The expansion of the universe will reverse and collapse on itself. The energy generated will create a new Big Bang, creating a new universe.
Big Bang: Matter will expand from a single point from a state of high density and matter. This will mark the birth of a new universe.
Basic Facts about Gravitational Waves
Invisible "ripples" in the Space-Time Continuum
Travel at the speed of light
186,000 miles per second / 299,337.984 Kilometers per second
11,160,000 miles per minute / 17,960,279.04 Kilometers per minute
669,600,000 miles per hour / 1,077,616,742.4 Kilometers per hour
There are four (4) defined categories
Continuous
Stochastic
Burst
Compact Binary Inspiral
What is LIGO?
The first proof of the existence of gravitational waves came in 1974. 20+ years after Einstein's death.
The first physical proof came in 2015, 100 years after his theory was published. The waves were detected by LIGO.
LIGO- Laser Interferometer Gravitational-Wave Observatory
The waves detected in 2015 came from 2 black holes that collided 1.3 billion years ago in the constellation Hydra. 1.3 billion years ago multicellular life was just beginning to spread on Earth, it was before the time of the dinosaurs!
Continuous Gravitational Waves
Produced by a single spinning massive object.
Caused by imperfections on the surface.
The spin rate of the object is constant. The waves are come at a continuous frequency.
Stochastic Gravitational Waves
Smalles waves
Hardest to detect
Possibly caused by remnants of gravitational radiation left over from the Big Bang
Could possibly allow us to look at the history of the Universe.
Small waves from every direction mixed together.
Burst Gravitational Waves
Never been detected.
Like ever.
Never ever.
Not once.
Nope
No
N E V E R
We don't know anything about them.
If we learn about them they could reveal the greatest revolutionary information about the universe.
Compact Binary Inspiral Gravitational Waves
All waves detected by LIGO fall into this category.
Produced by orbiting pairs of massive and dense objects. (Neutron Stars, Black Holes)
Three (3) subclasses
Binary Neutron Star (BNS) // Two (2) Neutron Stars colliding
Binary Black Hole (BBH) // Two (2) Black Holes colliding
Neutron Star- Black Hole Binary (NSBH) // A black hole and a neutron star colliding
Each subclass creates its own unique wave pattern.
Waves are all caused by the smae mechanism called an "inspiral".
Occur over millions of years.
Over eons the objects orbit closer together.
The closer they get, the faster they spin.
Sources Used:
On The Shoulders Of Giants by Stephen Hawking
Oxford Astronomy Encyclopedia
@watch-out-idiot-passing-through @nasa
Women who had ADHD (24%) [were more likely to have attempted suicide] compared to women who had not (3%).
Men with ADHD were also more likely to have attempted suicide compared to men without ADHD (9% vs. 2%).
Adults with ADHD were much more likely to have attempted suicide than those without (14.0% vs. 2.7%).
(Study in full)
Q: Is your mind organized?
A: yes and no. Quantum mechanical order, so to speak.
#laughsinquantummechanicalsuperpositionwhilecrying
We’re on the verge of launching a new spacecraft to the Sun to take the first-ever images of the Sun’s north and south poles!
Credit: ESA/ATG medialab
Solar Orbiter is a collaboration between the European Space Agency (ESA) and NASA. After it launches — as soon as Feb. 9 — it will use Earth’s and Venus’s gravity to swing itself out of the ecliptic plane — the swath of space, roughly aligned with the Sun’s equator, where all the planets orbit. From there, Solar Orbiter’s bird’s eye view will give it the first-ever look at the Sun’s poles.
Credit: ESA/ATG medialab
The Sun plays a central role in shaping space around us. Its massive magnetic field stretches far beyond Pluto, paving a superhighway for charged solar particles known as the solar wind. When bursts of solar wind hit Earth, they can spark space weather storms that interfere with our GPS and communications satellites — at their worst, they can even threaten astronauts.
To prepare for potential solar storms, scientists monitor the Sun’s magnetic field. But from our perspective near Earth and from other satellites roughly aligned with Earth’s orbit, we can only see a sidelong view of the Sun’s poles. It’s a bit like trying to study Mount Everest’s summit from the base of the mountain.
Solar Orbiter will study the Sun’s magnetic field at the poles using a combination of in situ instruments — which study the environment right around the spacecraft — and cameras that look at the Sun, its atmosphere and outflowing material in different types of light. Scientists hope this new view will help us understand not only the Sun’s day-to-day activity, but also its roughly 11-year activity cycles, thought to be tied to large-scales changes in the Sun’s magnetic field.
Solar Orbiter will fly within the orbit of Mercury — closer to our star than any Sun-facing cameras have ever gone — so the spacecraft relies on cutting-edge technology to beat the heat.
Credit: ESA/ATG medialab
Solar Orbiter has a custom-designed titanium heat shield with a calcium phosphate coating that withstands temperatures more than 900 degrees Fahrenheit — 13 times the solar heating that spacecraft face in Earth orbit. Five of the cameras look at the Sun through peepholes in that heat shield; one observes the solar wind out the side.
Over the mission’s seven-year lifetime, Solar Orbiter will reach an inclination of 24 degrees above the Sun’s equator, increasing to 33 degrees with an additional three years of extended mission operations. At closest approach the spacecraft will pass within 26 million miles of the Sun.
Solar Orbiter will be our second major mission to the inner solar system in recent years, following on August 2018’s launch of Parker Solar Probe. Parker has completed four close solar passes and will fly within 4 million miles of the Sun at closest approach.
Solar Orbiter (green) and Parker Solar Probe (blue) will study the Sun in tandem.
The two spacecraft will work together: As Parker samples solar particles up close, Solar Orbiter will capture imagery from farther away, contextualizing the observations. The two spacecraft will also occasionally align to measure the same magnetic field lines or streams of solar wind at different times.
The booster of a United Launch Alliance Atlas V rocket that will launch the Solar Orbiter spacecraft is lifted into the vertical position at the Vertical Integration Facility near Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida on Jan. 6, 2020. Credit: NASA/Ben Smegelsky
Solar Orbiter is scheduled to launch on Feb. 9, 2020, during a two-hour window that opens at 11:03 p.m. EST. The spacecraft will launch on a United Launch Alliance Atlas V 411 rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida.
Launch coverage begins at 10:30 p.m. EST on Feb. 9 at nasa.gov/live. Stay up to date with mission at nasa.gov/solarorbiter!
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why are cheetahs not technically big cats? is it just because they're weird as hell or do they not meet some big cat criteria?
so the thing about Big Cats is that they’re all closely related members of the genus Panthera!
because they’re all part of the same lineage, they share a lot of traits like the ability to roar.
and cheetahs are actually members of a completely different cat lineage altogether, the genus Acinonyx!
they’re not very closely related to the big cats at all and are actually most closely related to Pumas, which you can totally see if you stack them up next to each other and squint really hard.
it’s okay though, the cheetah can still be the biggest cat in our hearts :’)
Spiral and elliptical galaxies seem neatly put together, but what happened to irregular galaxies? Irregular galaxies have one-of-a-kind shapes and many look like blobs! Why do they look the way they do? Astronomers think the uniqueness of these galaxies results from their interactions with other galaxies — like when they pass close to one another or even collide!
Looking back at the early universe with the help of our Hubble Space Telescope’s “deep field” observations, astronomers can peek at galaxies millions and billions of light-years away. They noticed that these far-away galaxies appear unusually messy, showing more star formation and mergers than galaxies closer to the Milky Way.
We also see irregular galaxies closer to home, though. Some may form when two galaxies pass close together in a near-miss. When this happens, their gravity pulls stars out of place in both galaxies, messing up the neat structure they originally had as spiral or elliptical galaxies. Think of it like this: you happen to have a pile of papers sitting at the edge of a table and when someone passes close by the papers become ruffled and may scatter everywhere! Even though the two galaxies never touched, gravity's effects leave them looking smeared or distorted.
Some irregular galaxies result from the collision between two galaxies. And while some of these look like a blob of stars and dust, others form dazzling ring galaxies! Scientists think these may be a product of collisions between small and large galaxies. These collisions cause ripples that disturb both galaxies, throwing dust, gas, and stars outward. When this happens, it pushes out a ring of material, causing gas clouds to collide and spark the birth of new stars. After just a few million years, stars larger than our Sun explode as supernovae, leaving neutron stars and black holes throughout the ring!
Not all galaxy collisions create irregular galaxies — our Milky Way spiral galaxy has gone through many mergers but has stayed intact! And for some interacting galaxies, being an irregular galaxy may just be a phase in their transformation. We’re observing them at a snapshot in time where things are messy, but they may eventually become neat and structured spirals and ellipticals.
Irregular galaxies are similar to each other, but unique and beautiful because of their different interactions, whether they’re just passing another galaxy or taking part in a dramatic collision. Keep up with NASA Universe on Facebook and Twitter where we post regularly about galaxies.
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Credits: NASA/Bill Ingalls
Have you noticed two bright objects in the sky getting closer together with each passing night? It’s Jupiter and Saturn doing a planetary dance that will result in the Great Conjunction on Dec. 21. On that day, Jupiter and Saturn will be right next to each other in the sky – the closest they have appeared in nearly 400 years!
Credits: NASA/JPL-Caltech
For those who would like to see this phenomenon for themselves, here’s what to do:
Find a spot with an unobstructed view of the sky, such as a field or park. Jupiter and Saturn are bright, so they can be seen even from most cities.
An hour after sunset, look to the southwestern sky. Jupiter will look like a bright star and be easily visible. Saturn will be slightly fainter and will appear slightly above and to the left of Jupiter until December 21, when Jupiter will overtake it and they will reverse positions in the sky.
The planets can be seen with the unaided eye, but if you have binoculars or a small telescope, you may be able to see Jupiter’s four large moons orbiting the giant planet.
Credits: NASA/Bill Dunford
Saturn and Jupiter are easy to see without special equipment, and can be photographed easily on DSLR cameras and many cell phone cameras. Here are a few tips and tricks:
These planets are visible in the early evening, and you’ll have about 1-2 hours from when they are visible, to when they set. A photo from the same location can look completely different just an hour later!
Using a tripod will help you hold your camera steady while taking longer exposures. If you don’t have a tripod, brace your camera against something – a tree, a fence, or a car can all serve as a tripod for a several-second exposure.
The crescent Moon will pass near Jupiter and Saturn a few days before the conjunction. Take advantage of it in your composition!
Get more tips HERE.
Our NASA expert answered questions from social media on an episode of NASA Science Live on Thursday, Dec. 17. Watch the recording HERE.
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"Equipped with his five senses, man explores the universe around him and calls the adventure science."
-Edwin P. Hubble