Four questions: Here there be monsters

Four Questions: Here There Be Monsters
dam Block's photo of the Messier 87 galaxy. Credit: Adam Block

On April 10, the world got to see the first image taken of a black hole in space, taken by the Event Horizon Telescope, a worldwide collaboration of astronomers and astrophysicists including a substantial team at the University of Arizona.

Adam Block, astrophotographer and operations specialist at the UA's Steward Observatory, took an image of Messier 87, the galaxy where astronomers took the first image of a black hole, as it would present itself to the eyes of a space-faring visitor. The image is one of very few showing the extensive glow caused by the roughly one trillion stars that call the M87 galaxy home, yet at the same time detailing the monstrous jet emanating from the supermassive black hole at its center – a feat difficult to achieve in the same image because of the vastly different exposure times required.

"When I take a picture like this one, every pixel only sees a tiny little piece of sky," Block said. "With the telescope I used (the Schulman Telescope at the Mount Lemmon SkyCenter) the resolution is 0.33 arcseconds per pixel, but with the EHT, they were able to resolve 40 micro arcseconds. If you could slice up one of the pixels in my image into 10,000 bits, the area around the supermassive black hole that EHT was able to resolve would be a single one of them. That gives you some idea of the amazing resolving power that the EHT collaboration was able to achieve. Going forward, EHT is going to observe at shorter wavelengths, and that will give them higher resolution."

UANews spoke to Block about his M87 photo, and the information it provides about the now-famous galaxy.

Why was the Event Horizon Telescope pointed at a galaxy 55 million light-years away?

Block: The supermassive black hole that was observed with the Event Horizon Telescope is in the center of a giant galaxy called M87, and that is exactly the kind of galaxy where we would expect to find a monster. We are looking at a massive, elliptical galaxy, not a spiral galaxy like our Milky Way. Even though it's just a little bigger in diameter than the Milky Way, because it is football-shaped, M87 is hundreds of times more massive. M87 probably is the biggest galaxy in the Virgo cluster. In fact, it is one of the most massive galaxies in the local universe.

Four Questions: Here There Be Monsters
A crop of the above image shows M87's jet in greater detail. The part of the jet that's visible in the optical light spectrum is about 8,000 light-years long. Credit: Adam Block

M87 also sits at the center of the Virgo cluster, an accumulation of about 2,000 galaxies that is the nearest large cluster of galaxies to us. Our Milky Way, on the other hand, is in a fairly quiet part of the local universe, a cosmic cul-de-sac, if you will. It's as if we were at the suburbs, and we'd be looking at that bright glow on the horizon, that big city closest to our quiet little town.

When a galaxy is in the center of a cluster, it tends to interact much more frequently with other galaxies. We think M87 grew so large because it has absorbed other galaxies over time, and that's important, because that's how you grow a supermassive black hole. If you don't have all this activity of galaxies colliding with other galaxies, you don't have enough raw material, and if there isn't a lot of material falling into the black hole, you don't see anything. The black hole in M87 is feeding, and that's why we see it.

In 2010, you took an image of M87 that was selected by NASA as the "Astronomy Picture of the Day." What does that image tell us about the galaxy and its supermassive black hole?

Block: The image is quite zoomed in. If you zoomed out and looked at it at a progressively wider field of view, you'd see more and more galaxies, all members of the Virgo cluster. Those fuzzy little spots surrounding the M87 galaxy all look like stars, but almost all of those are ancient, globular star clusters. There is no star formation taking place here, because for that you need cold clouds of gas that can collapse, but that requires a bit of a quieter area. In M87, where you have stars whipping around due to the interactions with other galaxies and the black hole itself injecting energy into the surroundings, that activity contributes to star formation being shut off.

According to one hypothesis, all those globular clusters of stars we see around M87 could be the remnants of small dwarf that M87 swallowed eons ago. So, all those little dots could literally be the leftover scraps showing the history of M87 growing. The picture is hinting at all of this monstrous galactic hunger, and of course that lends credence to the idea of the formation of the supermassive black hole.

We also see the jet of shooting out of what is believed to be the supermassive black hole at its center – a testament to how big M87 is as a place. The accretion disc swirling around the black hole emits light across the entire electromagnetic spectrum, from gamma rays to radio waves, which is what EHT detected. In fact, M87 is the brightest radio source in that direction in the sky. All that mass and all that astrophysical activity is what made it possible for a to exist in a way that made it observable. We are very fortunate in that sense, and all those things are part of the story of M87, making it one of the best places that astronomers wanted to look for something as remarkable as a black hole.

Four Questions: Here There Be Monsters
Artist impression of a black hole with an accretion disk and jet. Credit: Mark Garlick

The jet is a very concrete consequence of having a black hole there, and it has its own characteristics. Astrophysicists think the jet consists of high-energy particles shooting out from the superheated gas and dust in the accretion disk around the black hole. Much of it is literally light – photons – but also ionized gas and electrons. The jet is what we call collimated – meaning it is focused, like a laser beam, and relativistic, which means that particles, superheated plasma and gas are moving out at velocities near the speed of light. The jet is directed toward our line of sight, and from our perspective, when you look at the light, it looks like it's moving faster. But it only appears as if it was traveling faster the speed of light. It's a relativistic effect following directly from Einstein's Theory of General Relativity.

The now famous image of M87's supermassive black hole captured it as it appeared 55 million years ago. What would it look like today?

Block: For all intents and purposes, black holes are almost like permanent structures of the cosmos in any reasonable time you can think about. Stephen Hawking proposed that black holes can 'leak' a little bit of energy, but that effect would be so small that it would take many times the current age of the universe for them to fade out of existence. Whether we see them or not only has to do with whether they're eating something. If they're just out there without consuming any matter, we can't see them. The black hole in M87 is definitely still there, and although the information you see in the picture is 55 million years old, the stars in that galaxy have been around for billions of years. The jet has been doing this for a very long time. These are very big objects, and the universe proceeds along times that are much different from our lifetimes, so everything moves very slowly. If we could travel to M87 now, we wouldn't see anything much different.

What excites you most about the image of M87's black hole?

Block: Until last week, pictures of unicorns and pictures of black holes were basically in the same category; and now, move into reality.


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Image: Computer simulation of a supermassive black hole

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Apr 18, 2019
The jet is a very concrete consequence of having a black hole there, and it has its own characteristics. Astrophysicists think the jet consists of high-energy particles shooting out from the superheated gas and dust in the accretion disk around the black hole.

They are riding the pseudoscientific BH claptrap right down through the non-existent event horizon.

Apr 20, 2019
The Conclusion drawn by EHT team is just an interpretation among a lot ones.

The alternative interpretation could be the following: the picture realised by EHT team is a confirmation of the "galactic toroidal plasmoid". Also the same picture affirms the plasma cosmology hypothesis that the object at a galactic core is not a BH at all but an ultra-high density energy storage phenomena called a PLASMOID.

References:

‒ Winston H. Bostick, "Experimental Study of Ionized Matter Projected across a Magnetic Field", Physical Review 104, 292 (1956)

‒ Winston H. Bostick, "Possible Hydromagnetic Simulation of Cosmical Phenomena in the Laboratory" (1958). International Astronomical Union. Symposium no. 8, p. 1090

‒Winston H. Bostick, "What laboratory-produced plasma structures can contribute to the understanding of cosmic structures both large and small" IEEE Transactions on Plasma Science 14, 703 (1986).


Apr 20, 2019
They are riding the pseudoscientific BH claptrap right down through the non-existent event horizon.


Which they have imaged, you scientifically illiterate Velikovskian clown. And you have no argument against it, other than it is just another observation that screws up your idiotic, quasi-religious belief system. Tough titties, woo boy. Get back to mythology, you ignorant clown.

Apr 20, 2019
The Conclusion drawn by EHT team is just an interpretation among a lot ones.

The alternative interpretation could be the following: the picture realised by EHT team is a confirmation of the "galactic toroidal plasmoid". Also the same picture affirms the plasma cosmology hypothesis that the object at a galactic core is not a BH at all but an ultra-high density energy storage phenomena called a PLASMOID.


Jesus, what a clown! Plasmoid! Lol. Are you another thicko electric universe loon? Show where Bostick, or anybody else, has used this scientifically impossible, never observed plasmoid woo, to explain the orbits around Sgr A*. And further, used the aforementioned laughable woo, to explain the gravitational redshift of star S0-2 at pericentre around Sgr A*. You know what? It hasn't been done. Know why? Because it is an extremely dumb idea.


Apr 20, 2019
Normal service is resumed

Our artist impression of a black hole with an accretion disk and jet
in
All its Technicolor glory
https://3c1703fe8...tion.jpg

Apr 20, 2019
What is this news we hear

M87, appears to have a quasar at its heart
If this is as it appears to be
true
it certainly gives our old friend, M87
a well earned character
as M87 was starting to look a mite bland of late
now
as it appears to have a quasar at heart
this
changes this whole outlook
now
M87 can look forward to a new interesting galactic chapter in its life
as blackhole and quasar are as one
Selfie is now also of M87s Quasar

Apr 20, 2019
What is this news we hear

M87, appears to have a quasar at its heart
If this is as it appears to be
true
it certainly gives our old friend, M87
a well earned character
as M87 was starting to look a mite bland of late
now
as it appears to have a quasar at heart
this
changes this whole outlook
now
M87 can look forward to a new interesting galactic chapter in its life
as blackhole and quasar are as one
Selfie is now also of M87s Quasar


Is there no end to your indecipherable crap?

Apr 20, 2019
This Haze of Contradiction

With a total mass of M87 200 times that of the Milky Way
with a diameter of 250,000Lys
gas infilling into the galaxy
with linear streams of stars to the northwest of M87
created by tidal stripping of orbiting galaxies
and
small satellite galaxies falling in toward M87
with its linear relativistic jet
extending 5000Lys from its core
as we observe 55million Lys distant
a diameter of 250,000Lys of billions of stars
Through this haze of stars far greater than our galaxy

For this is this Contradiction
when compared to our Milkyway
which is
Miniscule when compared to M87

Apr 20, 2019
Lost in all the bullshit is the fact that the only plasmoids we know of happen in energetic environments and are expelled from them.

So what's making all the energy in the middle of M87? And how come there's only one plasmoid, with all this energy there?

This is why woo is woo. Wooboi sez "it's a plasmoid," and when someone asks, "where's all the energy making this plasmoid, and where are the other plasmoids," there's a thundering silence.

Apr 20, 2019
Just to put a finer point on it, what's in the middle of the black spot making enough energy to create plasmoids?

Just askin'.

Apr 20, 2019
Plasmoids occur in Earth's magnetosphere, the SW, on the Sun, HCS, and now observed in galactic cores, just as predicted.
Galactic plasmoids are larger and more energetic due to the larger currents at the galactic center. A solar system size plasmoid fed by galactic dimension currents will store and then emit a tremendous amount of energy, and create a galactic size magnetic field.

Apr 20, 2019
And in every case plasmoids form from energy.

Where's the energy?

Remember, the electric force is 240,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 times stronger than gravity. Even from M87 we'd be able to detect such an electric force. We don't.

So what's making this supposed plasmoid? I got gravity, and it's not a plasmoid. You got unicorns making magic lightning.

I'm going with gravity.

Next?

Apr 20, 2019
Even from M87 we'd be able to detect such an electric force.

What do you expect the "detection" of the electric force would look like that you aren't seeing?

So what's making this supposed plasmoid? I got gravity, and it's not a plasmoid.

Already explained, galactic size Birkeland currents.

You got unicorns making magic lightning.

Plasmoids are real, plasma physicists agree the scalability of which is within the physical limitations of plasma physics.
BH's are maths based speculations with no physical meaning or mechanism to explain your supposed gravity monster.

Apr 20, 2019
What do you expect would the "detection"
You know, voltage meters and stuff. Standard laboratory equipment you've never seen.

If you'd ever have seen any such equipment, you'd know the first thing anyone using it does is wave it around. If the measurements change you've found a Nobel Prize. Or an incompetent technician.

Apr 20, 2019
You know, voltage meters and stuff. Standard laboratory equipment you've never seen.

What's the voltage of the TV in my living room? Use your voltage meter from where you are at.

Apr 21, 2019
What kind of TV? You mean a CRT? OK, how big? It matters you know. Or you would if you weren't just posing again.

And just to drive the point home, assuming it's a CRT, do you mean the cathode scanning voltage, and the average or peak of that voltage, or do you mean the second anode voltage?

And why would you assume your TV can make as much electric field as a star, or a galaxy?

Cranks can't count.

240,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 worth.

Apr 21, 2019
I hypothesize that when a star explodes it creates a cavitation. Just like a firecracker exploding underwater creates a cavitation bubble. That bubble then implodes. In the case of the firecracker, the implosion of water would hit itself in the middle. The same sort of thing also happens when smaller stars explode. Its the big star explosions that subsequently cause an implosion with enough speed and divergence needed to 'orbit' the vacuum its trying to fill, creating a black hole. A region of empty space...a pure vacuum...that could only be orbited like that at nearly the speed of light. Since nothing can go the actual speed of light, the black hole will eventually dissipate.

Apr 21, 2019
When a galaxy is in the centre of a cluster

Frequent interactions occur with other galaxies
M87 has grown large because it has absorbed other galaxies
If you don't have all this activity of galaxies colliding with other galaxies
you don't have enough raw material
and
if there isn't a lot of material falling into the black hole
you don't see anything
This black hole in M87 is feeding, that's why we see it

Selfie is 44billion km by 55million Lys a ratio 800:1
where as
Sagittarius A* is 44milion km by 25thousand Lys a ratio 1760:1
thiseth
meaneth Sagittarius A* is 2.2 times as close to earth as Selfie
Sagittarius A* is twice as close to earth than selfie
Sagittarius A* appears 2.2 times larger to earthling as Selfie
so as a figure of 38billion kms is bandied around
a good approximation
Sagittarius A* is twice as large proportionally speaking than Selfie
so
In this vacuous vacuum of proportionality in dimensions

Sagittarius A* is Twice as Large as Selfie

Apr 21, 2019
When a galaxy is in the centre of a galactic cluster

Where that galaxy is a galaxy of billions of stars
surrounded
by thousands of galaxies
where
each one of those surrounding galaxies is composed of billions of stars
where in this enormous cluster of trillions of stars
sits
our Selfie
in an elliptical galaxy of even more billions of stars
an elliptical galaxy
that blocks this light more effectively than our spiral galaxy
so
Proportionally speaking

We have Selfie half the size of Sagittarius A*
We have Selfie more obscured than Sagittarius A*

To top it all
this
Selfie might not be the Selfie we think it to be
because
M87 has a Quasar at Heart
https://3c1703fe8...tion.jpg

Apr 21, 2019
Quasi stellar objects

The term quasar originated as a contraction of quasi-stellar radio source
identified in the 1950s as a radio-wave emission
when identified in photographic images at visible wavelengths they resembled faint star-like points of light
high-resolution images of quasars
from the Hubble Space Telescope
have demonstrated that quasars occur in the centres of galaxies
That some host-galaxies are strongly interacting or merging galaxies

M87 is a radio galaxy
M87 is a huge collection of merging galaxies
as
M87 has its relativistic jets
in
fact M87 has 5000Lys of relativistic jets
it has
all the ingredients required for this Quasi stellar object
as
we have
this Selfie half the size of Sagittarius A*
we have Selfie more obscured than Sagittarius A*
as
Selfie illuminating through these trillions of stars
with
its
quasi stellar object
Selfies Quasar

Apr 21, 2019
Da Schneib

Your observation: So what's making all the energy in the middle of M87
Da Schneib

Lost in all the bullshit is the fact that the only plasmoids we know of happen in energetic environments and are expelled from them.

So what's making all the energy in the middle of M87? And how come there's only one plasmoid, with all this energy there?

This is why woo is woo. Wooboi sez "it's a plasmoid," and when someone asks, "where's all the energy making this plasmoid, and where are the other plasmoids," there's a thundering silence.

Da Schneib, old bean
M87 contains a Quasar, that is enough power for whatever M87 requires!

Apr 21, 2019
The Conclusion drawn by EHT team is just an interpretation among a lot ones.


It is irritating when crackpot comments are in Crackpot SPELLING; I will explain and then block (so don't bother respond).

It is obvious that you have not read their 6 initial papers, since they don't draw a single conclusion. They list a lot of possible images (some constraints goes into producing it) and possible physics (several models fit).

But the overall work show that general relativity, black holes and an ergosphere is the simplest, mots likely explanation for what is seen. Therefore it is accepted by most that this was a win for relativity (and GRMHD) and that the black holes that has been best observed in gravity waves now has a more detailed observation by optical means.

One thing they obviously do not propose is something electric charge driven since large astronomical objects are neutralized by available free charges. The accretion disk and jet ionization are ambipolar, of course.

Apr 21, 2019
I hypothesize that when a star explodes it creates a cavitation. ... Its the big star explosions that subsequently cause an implosion with enough speed and divergence needed to 'orbit' the vacuum its trying to fill, creating a black hole. A region of empty space...a pure vacuum...that could only be orbited like that at nearly the speed of light.


This looks like free association stringing words together.

First off, the M87* super massive black hole was almost certainly not formed from stars but early universe gas turbulence, and the LIGO black holes were all mergers (of black holes or stars).

But fair enough, some black holes are thought to be remains of supernova explosions, and though it has been hard to model the explosion remains collapse it seems like it could happen that way. And the best models do have a rebound shock wave that *asymmetrically* (it is key) drive the collapse.

- tbctd -

Apr 21, 2019
- ctd -

But the collapse fill the core volume with dense matter, since too dense matter energy makes a black hole in general relativity, A field vacuum has no energy (aside from its here insignificant small dark - vacuum energy field fluctuation - energy density) [ https://en.wikipe...e#Energy ].

I also give you the theoretical construct of a photon shell, the imaginary boundary where a photon could - in the absence of disturbances - circle the black hole held by its gravitation. But the black hole putative evaporation would be a quantum field effect [ https://en.wikipe...adiation ].

Apr 21, 2019
I did not have space to write out GRMHD = General Relativitistic MagnetoHydroDynamics simulations. But this was a good test, like LIGO I think, that they suffice to explain the physics of what is seen.

Besides that these object are driven by gravity since that is the only potential energy source around, the explicit modeling concur.

Apr 21, 2019
Plasmoids are real, plasma physicists agree the scalability of which is within the physical limitations of plasma physics.
BH's are maths based speculations with no physical meaning or mechanism to explain your supposed gravity monster.


Please explain the orbits of the stars around Sgr A* using plasmoid woo. Explain the gravitational redshift of star S0-2 at pericentre around said object. How many times have I asked this? How many times have you run away from it? You do not have even the beginnings of a hypothesis. It is pure woo.

Apr 21, 2019
Plasmoids occur in Earth's magnetosphere, the SW, on the Sun, HCS, and now observed in galactic cores, just as predicted.
Galactic plasmoids are larger and more energetic due to the larger currents at the galactic center. A solar system size plasmoid fed by galactic dimension currents will store and then emit a tremendous amount of energy, and create a galactic size magnetic field.


Lol. Pure word salad. Rather pathetic.

Apr 21, 2019
Contrary to what EHT team wrote in their first article, the concept of BH cannot be deduced from Schwarzschild's original solution (1916). There is only one singularity in Schwarzschild's solution, at r = 0, to which his solution is constructed. BHs cannot be predicted in the context and formalism of GRT for multiple reasons.

Historically, John Michell (1784) and Simon Laplace (1796) predicted the existence of dark star, i.e., BH in the context and formalism of Newton's mechanics and gravity.

The investigation of the orbital motion of stars around Sgr A* has been performed in the context and formalism of Newton's gravity theory. There is no a single equation from GRT.


Apr 21, 2019
Energy flows to where energy is not. The empty space within a black hole is where energy is not (dark stuff also not there). I think gravity is the acceleration toward a true vacuum. Every atom in the Earth has neutron-proton interaction similar to black holes. All that empty space has a lot of collective pull. The orbiting plasma stuff is like a proton, black hole a neutron (no dark stuff). The dark stuff is in the space outside a black hole.

Apr 21, 2019
cantdrive should have a plugin gravity machine by now ?

Apr 21, 2019


The investigation of the orbital motion of stars around Sgr A* has been performed in the context and formalism of Newton's gravity theory. There is no a single equation from GRT.



That there is a very large mass at Sgr A* is confirmed from GR by the gravitational redshift of S0-2 at pericentre.

Apr 21, 2019
This Immutable Law of Physics, this Inverse Square Law

Selfie is 44billion km by 55million Lys and 1billion solar mass's
where as
Sagittarius A* is 44milion km by 25thousand Lys and 4million solar mass's
as
the mass of these blackholes is a measure of their output
by dividing their mass by the square of their distance
means
Selfie = 3.31x10-7
Sagittarius A* = 6.4x10-3
shows
that relative to Sagittarius A* size and distant compared the same with Selfie
thiseth
meaneth relatively specking
Sagittarius A* is 19,360 times brighter
due to this immutable law of physic this inverse square law
so in round figures
Sagittarius A* 20,000 times brighter than Selfie in M87
for
That day we decide to give our Sagittarius A* a Selfie all of its own

The Question is, as Sagittarius A* is 20,000 times brighter than Selfie, relatively speaking
what
is
this
aversion
to
Sagittarius A* having its own Selfie!

Apr 21, 2019
This comment has been removed by a moderator.

Apr 21, 2019
This comment has been removed by a moderator.

Apr 21, 2019
Actually the gravitational redshift can be deduced from Newton's gravity theory by combining

"gravitational mass" x g = "inertial mass" x a


Wrong. Gravitation redshift is a direct prediction of GR. It comes from the prediction of time dilation, which is not part of Newton's theory.

Apr 22, 2019

‒Wrong. Gravitation redshift is a direct prediction of GR. It comes from the prediction of time dilation, which is not part of Newton's theory.‒

Your claim is not correct. Exactly like the prediction of dark star (i.e., BH), historically and physically, "gravitational redshift" has been predicted by John Michell (1783) and Simon Laplace (1796), they called it "The gravitational weakening of light from high-gravity stars".

In 1907, the gravitational redshift has been hypothesed by Einstein Ref.[ A. Einstein ,Jahrb.Radioaktivitat Elektronik 4, 411 (1907)]., that's before GRT (1916). Actually, the gravitational redshift is a simple consequence of Einstein's equivalence principle.

Recall, equivalence principle itself is a direct consequence of: "gravitational mass" x g = "inertial mass" x a


Apr 22, 2019

‒Wrong. Gravitation redshift is a direct prediction of GR. It comes from the prediction of time dilation, which is not part of Newton's theory.‒

Your claim is not correct. Exactly like the prediction of dark star (i.e., BH), historically and physically, "gravitational redshift" has been predicted by John Michell (1783) and Simon Laplace (1796), they called it "The gravitational weakening of light from high-gravity stars".

In 1907, the gravitational redshift has been hypothesed by Einstein Ref.[ A. Einstein ,Jahrb.Radioaktivitat Elektronik 4, 411 (1907)]., that's before GRT (1916). Actually, the gravitational redshift is a simple consequence of Einstein's equivalence principle.

Recall, equivalence principle itself is a direct consequence of: "gravitational mass" x g = "inertial mass" x a



Wrong.

Apr 22, 2019
From data up to and including pericentre, we robustly detect the combined gravitational redshift and relativistic transverse Doppler effect for S2 of z ~ 200 km/s / c with different statistical analysis methods. When parameterising the post-Newtonian contribution from these effects by a factor f, with f = 0 and f = 1 corresponding to the Newtonian and general relativistic limits, respectively, we find from posterior fitting with different weighting schemes f = 0.90 +/- 0.09 (stat) +\- 0.15 (sys). ***The S2 data are inconsistent with pure Newtonian dynamics.***


Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole
Gravity Collaboration
https://arxiv.org...07.09409


Apr 22, 2019
Interesting
jonesy> Gravitation redshift is a direct prediction of GR. It comes from the prediction of time dilation, which is not part of Newton's theory

Was Sir Isaac Newton working on time dilation?

Apr 22, 2019
Was Sir Isaac Newton working on time dilation?


Google is available to everybody;

Time dilation by the Lorentz factor was predicted by several authors at the turn of the 20th century.[5][6] Joseph Larmor (1897), at least for electrons orbiting a nucleus, wrote "... individual electrons describe corresponding parts of their orbits in times shorter for the [rest] system in the ratio : SQRT 1 - v^2/ c^2".[7] Emil Cohn (1904) specifically related this formula to the rate of clocks.[8] In the context of special relativity it was shown by Albert Einstein (1905) that this effect concerns the nature of time itself, and he was also the first to point out its reciprocity or symmetry.[9] Subsequently, Hermann Minkowski (1907) introduced the concept of proper time which further clarified the meaning of time dilation.[10]


https://en.wikipe...dilation

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