edit: gravity

When Dead Stars Collide!

Gravity has been making waves - literally.  Earlier this month, the Nobel Prize in Physics was awarded for the first direct detection of gravitational waves two years ago. But astronomers just announced another huge advance in the field of gravitational waves - for the first time, we’ve observed light and gravitational waves from the same source.

There was a pair of orbiting neutron stars in a galaxy (called NGC 4993). Neutron stars are the crushed leftover cores of massive stars (stars more than 8 times the mass of our sun) that long ago exploded as supernovas. There are many such pairs of binaries in this galaxy, and in all the galaxies we can see, but something special was about to happen to this particular pair.

Each time these neutron stars orbited, they would lose a teeny bit of gravitational energy to gravitational waves. Gravitational waves are disturbances in space-time - the very fabric of the universe - that travel at the speed of light. The waves are emitted by any mass that is changing speed or direction, like this pair of orbiting neutron stars. However, the gravitational waves are very faint unless the neutron stars are very close and orbiting around each other very fast.

As luck would have it, the teeny energy loss caused the two neutron stars to get a teeny bit closer to each other and orbit a teeny bit faster.  After hundreds of millions of years, all those teeny bits added up, and the neutron stars were *very* close. So close that … BOOM! … they collided. And we witnessed it on Earth on August 17, 2017.  

Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet

A couple of very cool things happened in that collision - and we expect they happen in all such neutron star collisions. Just before the neutron stars collided, the gravitational waves were strong enough and at just the right frequency that the National Science Foundation (NSF)’s Laser Interferometer Gravitational-Wave Observatory (LIGO) and European Gravitational Observatory’s Virgo could detect them. Just after the collision, those waves quickly faded out because there are no longer two things orbiting around each other!

LIGO is a ground-based detector waiting for gravitational waves to pass through its facilities on Earth. When it is active, it can detect them from almost anywhere in space.

The other thing that happened was what we call a gamma-ray burst. When they get very close, the neutron stars break apart and create a spectacular, but short, explosion. For a couple of seconds, our Fermi Gamma-ray Telescope saw gamma-rays from that explosion. Fermi’s Gamma-ray Burst Monitor is one of our eyes on the sky, looking out for such bursts of gamma-rays that scientists want to catch as soon as they’re happening.

And those gamma-rays came just 1.7 seconds after the gravitational wave signal. The galaxy this occurred in is 130 million light-years away, so the light and gravitational waves were traveling for 130 million years before we detected them.

After that initial burst of gamma-rays, the debris from the explosion continued to glow, fading as it expanded outward. Our Swift, HubbleChandra and Spitzer telescopes, along with a number of ground-based observers, were poised to look at this afterglow from the explosion in ultraviolet, optical, X-ray and infrared light. Such coordination between satellites is something that we’ve been doing with our international partners for decades, so we catch events like this one as quickly as possible and in as many wavelengths as possible.

Astronomers have thought that neutron star mergers were the cause of one type of gamma-ray burst - a short gamma-ray burst, like the one they observed on August 17. It wasn’t until we could combine the data from our satellites with the information from LIGO/Virgo that we could confirm this directly.

This event begins a new chapter in astronomy. For centuries, light was the only way we could learn about our universe. Now, we’ve opened up a whole new window into the study of neutron stars and black holes. This means we can see things we could not detect before.

The first LIGO detection was of a pair of merging black holes. Mergers like that may be happening as often as once a month across the universe, but they do not produce much light because there’s little to nothing left around the black hole to emit light. In that case, gravitational waves were the only way to detect the merger.

Image Credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)

The neutron star merger, though, has plenty of material to emit light. By combining different kinds of light with gravitational waves, we are learning how matter behaves in the most extreme environments. We are learning more about how the gravitational wave information fits with what we already know from light - and in the process we’re solving some long-standing mysteries!

Want to know more? Get more information HERE.

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but you can leave if you really want to
and you can run if you feel you have to
and i can drink if i feel i have to
i know it’s hard, but i can’t feel
like i used to
like i used to
cause i used to

defy gravity
defy gravity
goodbyes keep draggin’ me

down.

and i’m fighting gravity
defying gravity
and i try but i keep fallin’
‘cause falling’s easy
but it only brings you

down.


- Eden, Gravity

youtube

Originally debuted at the MomoCon panel. Here’s the extended scene from “Weirdmageddon Part 1.”

8

Listen, do you wanna go back, or do you wanna stay here? I get it. It’s nice up here. You can just shut down all the systems, turn out all the lights, and just close your eyes and tune out everyone. There’s nobody up here that can hurt you. It’s safe. I mean, what’s the point of going on? What’s the point of living? Your kid died. Doesn’t get any rougher than that. But still, it’s a matter of what you do now. If you decide to go, then you gotta just get on with it. Sit back, enjoy the ride. You gotta plant both your feet on the ground and start livin’ life. Hey, Ryan? It’s time to go home.

Gravity | 2013 | dir. Alfonso Cuarón

anonymous asked:

Are you shorter when you re standing?

That’s a good question. I believe the answer is YES and I will tell you why I think that is true.

But I did search online for reliable scientific articles but didn’t find any! So, if you find one let me know


Measure it yourself!

You can actually take a tape and measure your height when you are standing and when you lying down.

And you WILL find that you are shorter by a few centimeters when you are standing.


Why ? ——–> Gravity

The reason why this supposedly happens is because the fluid in your spine compresses due to the pull of gravity. And as a result you become shorter by a few centimeters.

But when you are lying down, your spinal fluid remains in an ‘uncompressed’ state and hence the perception of feeling ‘taller’.

EDIT:

Taller in the morning, shorter in the evening

When we get up from bed in the morning the cartilages in our knees and other areas are in a ‘decompressed’ state. And as the day wears on, these cartilages are compressed under the influence of gravity, making us shorter.

Thank you Anon! Have a great one!

Gravity Anomaly Model of the Earth

These “gravity anomaly” maps show where Earth’s gravity field based on Gravity Recovery And Climate Experiment (GRACE) data differs from a simplified Earth model that is perfectly smooth and featureless. Areas colored yellow, orange, or red are areas where the actual gravity field is large, such as the Himalayan Mountains in Central Asia (top left of the left-hand globe) - while the progressively darker shades of blue indicate places where the gravity field is smaller-such as the area around Hudson Bay in Canada (top center of right-hand globe).