coolest physics thing that u know??

fuckyeahphysica:

The coolest physics thing that I know keeps changing over time. But here is one that is extremely fascinating ( and also exaggerated for the effect ; but true! ):

Person living at the top of a skyscraper experiences time faster than one at the bottom

It is a known fact that the higher you are in the earth’s ** atmosphere, the lesser the effect of gravity is.

But the lesser the effect of gravity is, the faster the time ticks.

image

By how much you ask? Even if you live on the top floor of the Burj Khalifa  your entire life, you would have aged more only by a few milliseconds than your friends at the bottom. 

( Sure, doesn’t seem like much, but hell would break loose if we don’t consider this on the bigger scale of things )

This is known as Gravitational time dilation and is at the foundations of General Theory of Relativity. (More about this in an upcoming post)

Have a great day and thanks for asking!

EDIT: ** Lets just say hypothetically the earth is not spinning( just to ignore special relativistic effects) and we are looking at only the effects of height.

Corollary – 1 : If your backyard has a black hole, then you would experience time slower than your neighbors.

image

Since the gravitational field around a black hole is much much stronger than earth, time starts to tick slower and slower for you than for your neighbor as you near a black hole.

Corollary – 2 : If you push your neighbor into a black hole, you have to wait literally forever to watch your neighbor fall into it, says GR. (Sublte to explain here, but covered in upcoming post)

image


Corollary – 3 : You cannot get bored while doing Special and General Relativity. There are always crazy scenarios to explore!

Have a great day!

fuckyeahphysica:

Celestial Wonders- Binary Stars (#1)

The twins of the stellar world are binary star systems.

A binary star is a
star system consisting of two stars orbiting around their common center
of mass.

When two stars appear close together in the sky as seen from the Earth when viewed through 
an optical telescope, the situation
is known as an “optical double”.

image

This means that although the
stars are aligned along the same line of sight, they may be at
completely different distances from us. This occurs in constellations;
however, two stars in the same constellation can also be part of a
binary system

 

Why study Binary stars ?

Binary star systems are very important in astrophysics because
calculations of their orbits allow the masses of their component stars
to be directly determined, which in turn allows other stellar
parameters, such as radius and density, to be indirectly estimated.

This
also determines an empirical mass-luminosity relationship (MLR) from
which the masses of single stars can be estimated.

image

Also,it is estimated that 75% of the stars in the Milky Way galaxy are
not single stars, like the Sun, but multiple star systems, binaries or
triplets.

The Brightest star in the sky is a binary.

This is true. Sirius (aka the Dog star)  – the brightest star in the sky is actually a binary star system.

When it was discovered in 1844 by the German astronomer
Bessel, the system was classed as an astro-metric binary, because the
companion star, Sirius B, was too faint to be seen.

image

Bessel, who was also
a mathematician, determined by calculations that Sirius B existed after
observing that the proper of Sirius A (the main star) followed a wavy
path in the sky, rather than a uniform path.

Sirius can now be studied
as a visual binary because, with improving technology and therefore
improved telescopes, Sirius B was able to be seen, although not for 20
years after Bessel had correctly predicted its existence.

image

Black Holes in a binary system ?

Hell Yeah! The term “binary system” is not used exclusively for star systems,
but also for planets, asteroids, and galaxies which rotate around a
common center of gravity.

However, this is not a trick question; even in
star binaries, the companion can be a black hole.

image

An example of this is
Cygnus X-1.

A binary Black Hole system ?

Definitely!
A binary black hole (BBH) is a system consisting of two black holes in close orbit around each other.

image

In fact the LIGO experiment which confirmed the existence of Gravitational waves was able to acquire its data when two Binary Black Holes Collided and merged into one. This phenomenon sent ripples in the fabric of space-time which we call as a Gravitational Wave.

The Universe is amazing huh?

If you found this interesting, check out:

A Denied stardom status – Jupiter

Black Holes are not so Black (Part 3) – Gravitational Waves

fuckyeahphysica:

Black Holes are not so Black (Part 3) – Gravitational Waves

The existence of Gravitational Waves have been confirmed. But you probably have heard that. In this post, we will break down this profound discovery into comprehend-able chunks.

This is going to be a amazing journey. Ready ?

Redefining Gravity

When we usually talk of Gravitation we are bound to think like Newton,
where objects are assumed to exerting a force upon each other.

Like
imaginary arrows of force in space. But this picture, although good for
high school crumbled, with the advent of Einstein’s theory of
Relativity.

image

What is the Space-Time Fabric?

Think of space-time fabric as
an actual cloth of fabric. ( An analogy )

image

When you place an object on the fabric, the
cloth curves. This is exactly what happens in the solar system as well.

image

The
sun with such a huge mass bends the space-time fabric. And the earth
and all the planets are kept in orbit by following this curvature that
has been made by the sun.

Attributing to the various masses of objects, the way they bend this fabric also varies.

image

What are Gravitational Waves?

If you drop an object in a medium such as water, they produce ripples that propagate as waves through the medium.

image

Similarly, Gravitational waves are ripples in space-time fabric produced when you drag heavy objects through space time.

And the nature of these waves is that they don’t require a medium to propagate.

How do you make one?

Everything with mass/energy can create these waves.

image

Source

Two persons dancing around each other in space too can create gravitational waves. But the waves would be extremely faint.

You need something big and massive accelerating through space-time in order to even detect them.

image

And orbiting binary stars/black holes are valuable in this retrospect.

How can you detect them?

Let’s turn to the problem to detecting them assuming you do find binary stars/black-holes in the wondrous space to suite your needs.

Well, for starters you cannot use rocks/ rulers to measure them because as the space expands and contracts, so do the rocks. ( the distances will remain same in both the cases )

image

Here’s where the high school fact that the speed of Light is a constant no matter what plays an important and pivotal role.

If the space expands, the time taken for light to reach from A to B would be longer. And if it contracts, the time taken for it to reach from A to B would be smaller.

image

PC: PHDComics

By allowing the light waves from the contraction and expansion to interfere with each other, such as done in any interferometry experiment we can detect the expansion or contraction. Voila!

image

And this is exactly what they did! ( on a macroscopic level ) at LIGO (Laser Interferometer Gravitational-Wave Observatory)

14 September 2015

image

Two Black Holes with masses of 29 and 36 solar masses merged together some 1.3 Billion light years away.

Two Black Holes colliding is the header animation of the ‘Black Holes are not so Black Series’, in case if you haven’t noticed.

image

The merger of these two black holes results in the emission of energy equivalent to 3 solar masses as Gravitational Waves.

This signal was seen by both LIGO detectors, in Livingston and Hanford,
with a time difference of 7 milliseconds.

And with the measurement of this time difference, physicists have pronounced the existence of Gravitational Waves.

image

Source

All this is most certainly easily said than done and requires meticulous and extensive research, not to mention highly sensitive instruments.

Had they not have measured this time difference,
we might have had to wait for the merger for more massive black holes
to collide and maybe even build more sensitive instruments to detect these waves.

And Einstein predicted this a 100 years back!

image

Mind Blown!

Note: Hope you are able to understand and appreciate the profundity of the discovery done by mankind.

** All animations used here are merely for Educational purposes. If you have any issues, please write to us at : 153armstrong@gmail.com

Why is this discovery a Big Deal ?

Gravitational waves gives
us another way to observe celestial phenomenon. These waves also form
when supernovae explode, when black holes collide and during many other
space activities.

image

Detecting them might give us a new
perspective into the cosmic events. There is hell of a lot of space that
is left unexplored or lies beyond human exuberance and this discovery
might shed some light on it. ( like the big bang per se )

The ultimate goal is to
understand the fundamental laws of the universe. It is a quest through
the oblivion towards a theory of everything.

image

Although it is
unknown how many years/decades it might take to get us there, but these discoveries
are markers to getting there.

What is this Image that i see everywhere?

image

This is not the photograph of the actual event but a simulation run by NASA of two black holes merging.

A2A: Anonymous

How does the actual experimental setup look like ?

The actual experimental setup is a bit complex in its entirety. But the guardian has an elegant image that seems to cover its essence:

image
image

A2A: Anonymous

Have a great day!

This is what happens when Two Black Holes Collide.

This is the animation of the final stages of a merger between two black holes. What is particularly interesting about this animation is that it highlights a phenomenon known as Gravitational Lensing.

What is Gravitational Lensing?

Mass bends Light. What? 

Yeah, mass can bend Light. The gravitational field of a really massive object is super strong. And this causes light rays passing close to that object to be bent and refocused somewhere else.

image

The more massive the object, the stronger its gravitational field and hence the greater the bending of light rays – just like using denser materials to make optical lenses results in a greater amount of refraction.

Here’s an animation showing a black hole going past a background galaxy.

image

This effect is one of the predictions of Einstein’s Theory of General Relativity 

PC: cfhtlensUrbane Legend

Celestial Wonders- Binary Stars.

image

The twins of the stellar world are binary star systems.A binary star is a star system consisting of two stars orbiting around their common center of mass.When two stars appear close together in the sky, the situation is known as an “optical double”. This means that although the stars are aligned along the same line of sight, they may be at completely different distances from us. This occurs in constellations; however, two stars in the same constellation can also be part of a binary system.

image

Artist’s impression of the sight from a (hypothetical) moon of planet HD 188753 Ab (upper left), which orbits a triple star system( yes, a Triple Star system!). The brightest companion is just below the horizon.

image

Binary star systems are very important in astrophysics because calculations of their orbits allow the masses of their component stars to be directly determined, which in turn allows other stellar parameters, such as radius and density, to be indirectly estimated. This also determines an empirical mass-luminosity relationship (MLR) from which the masses of single stars can be estimated.

It is estimated that approximately 1/3 of the star systems in the Milky Way are binary or multiple, with the remaining 2/3 consisting of single stars.

The Brightest star in the sky is a binary.

image

This is true. When it was discovered in 1844 by the German astronomer Bessel, the system was classed as an astrometric binary, because the companion star, Sirius B, was too faint to be seen. Bessel, who was also a mathematician, determined by calculations that Sirius B existed after observing that the proper of Sirius A (the main star) followed a wavy path in the sky, rather than a uniform path. Sirius can now be studied as a visual binary because, with improving technology and therefore improved telescopes, Sirius B was able to be seen, although not for 20 years after Bessel had correctly predicted its existence.

Black Holes in a binary System ?

image

The term “binary system” is not used exclusively for star systems, but also for planets, asteroids, and galaxies which rotate around a common center of gravity. However, this is not a trick question; even in star binaries, the companion can be a black hole. An example of this is Cygnus X-1.

The universe is pretty amazing huh?…