After decades of research, the first findings point to the existence of the mysterious waves
Scientists from the LIGO detector in the United States announced for the first time the discovery of gravitational waves. The director of the detector, David Reitze, reported that in September of last year, waves were observed created by the collision of two black holes 1.3 billion years ago. Since September, researchers at the detector have been diligent about checking the data and verifying it, and this evening (Thursday) they announced the discovery.
A century-old prediction
Albert Einstein predicted the existence of gravitational waves as early as 1916, as part of the theory of general relativity. He described the movement of bodies in curved space-time, which leads to a gravitational force acting between them. For example, you can think of a bowling ball placed in the center of a large trampoline: the heavy ball stretches the fabric and springs and curves the trampoline surface. If we put a tennis ball there, it will roll and be attracted to the bowling ball because of the depression created by the heavy ball. In a similar way stars curve the space-time around them and the other bodies moving in the curved space-time are attracted to them. The force acting between the star and the various bodies is gravity.
Now let's go one step further: if we place two bowling balls in the center of the trampoline and let them circle around each other, their movement will cause the trampoline surface to constantly move and change its shape. If we look at the edges of the surface it seems that they also move, because the movement of the balls creates waves in the surface that move from the center to the edge. Similarly, according to the theory of relativity, when large and massive stars move in cycles in space-time, it curves and changes cyclically and gravitational waves are created in it.
Faint echoes
Since Einstein's prediction, physicists have tried to measure these gravitational waves, but the task is not simple at all, because these waves are very weak. Gravitational force is the weakest of the four physical forces, and gravitational waves are actually tiny changes in gravitational force that move through space. As you move away from the source of the waves, they fade, so the chance of discovering weak waves that have traveled huge distances in the universe and decayed is very small and requires particularly sensitive instruments.
One of the ways to measure weak forces is to amplify the signals through the phenomenon of resonance (resonance) - a very strong response of a system to a certain frequency called the "eigenfrequency of the system" or the "resonance frequency". A common example of this is a hanging swing. If we push it, even a weak push, at a constant rate corresponding to its resonant frequency, the oscillation will increase quickly and we can reach heights. If we swing the swing at a rate different from its resonant frequency, the reaction will be much weaker and the push will not be effective.
The first attempt to measure gravitational waves was made using a "Weber rod" - a device invented by Joseph Weber in the 60s. The device includes large, heavy aluminum rods that vibrate when a gravitational wave passes through them. If the gravity wave vibrates the rods at their resonant frequency, the response will be strong and the rods will vibrate with large oscillations.
In 1968, Weber announced that he was able to measure gravitational waves with this method, but attempts to reproduce his measurements did not turn up anything and it seems that he made a mistake in the analysis of the measurements and did not correctly account for background noise. Although Weber's attempt was unsuccessful, he opened the search for gravitational waves and laid the foundations for other researchers who followed him.
Over the years, more detectors of gravitational waves have been established, which work with similar methods. Among them were the AURIGA detectors in northern Italy or the Leiden University detector in the Netherlands, which consists of a heavy metal ball instead of rods. They too have yielded no results so far.
high sensitivity
The most advanced means of measuring gravitational waves, which is also responsible for the current rumors on the subject, is the LIGO detector (acronym for Laser Interferometer Gravitational-Wave Observatory), in the United States. It was built at a cost of about 620 million dollars with the cooperation of 14 countries. More than 900 scientists are engaged in the planning and execution of the measurement experiments in the two detection systems, in Louisiana and Washington State.
LIGO's measurement is based on a method called "interferometry" - first a laser beam is split into two different directions (two arms). At the end of each arm there is a mirror that brings the rays back to the splitting point, where the rays come back and meet, and struggle through. If the light waves return and both are at the peak of the wave, they will amplify each other (constructive interference). If one wave is at its peak and the other is opposite, they will cancel each other out (destructive interference). Using a power detector you can distinguish between the two cases and know if the rays traveled an equal distance.
When a gravitational wave passes through the experimental area, space-time expands and contracts and the distances traveled by the two rays change. Accordingly, the interference pattern will also change, and we are trying to measure these changes in LIGO. The problem is that the gravitational wave will produce a very small change, of about 10 to the power of minus 19 meters (a tenth of a billionth of a billionth of a meter, ie about 1/10,000 of the size of a proton!). To measure this change, a very sensitive detector is needed and you also need to know how to differentiate between the gravitational wave and external noises, which can be caused by tiny earthquakes or even a car driving nearby.
LIGO is the largest and most sensitive interferometer in the world. The laser beams move inside an empty tube, each arm of which is four kilometers long. There are mirrors at the ends of the arms and the rays pass between them 400 times, which means that each ray goes through a path of 1,600 km before it reaches the detector itself! This long track increases the sensitivity of the system and its ability to notice even tiny changes. The detector is also isolated from external vibrations and noises, to ensure that only the changes in the interference pattern resulting from gravitational waves will be measured.
On September 14.9.2015, 1.3, the LIGO detector detected oscillations created by the collision of two black holes 30 billion light years away. Each of them is about 150 times heavier than our sun, although they are only about XNUMX km in diameter. The two black holes circled each other and gradually got closer to each other, until they merged into one black hole in a violent event that created very strong gravitational waves. These waves set out while life on Earth was in its infancy, but eventually arrived here, creating tiny oscillations in LIGO's laser beams.
The researchers were able to verify the source of the waves because a similar disturbance was picked up a few milliseconds apart, first at a detector in Louisiana and then at a similar detector in Washington state. Such an observation also strengthens the assessment that this is an actual cosmic event and not background noise, and also allows researchers to identify the direction from which the waves came, thus tracing their origin.
The researchers further explained that the signal created in such a collision has a unique characteristic - its frequency and intensity gradually increase until the peak point of the merging of the black holes, after which they gradually fade. These properties were calculated according to Einstein's prediction and the findings matched the calculations with great precision.
complete the puzzle
The most isolated place from noise and external disturbances is space. That is why the European Space Agency (ESA) launched the LISA Pathfinder spacecraft at the end of 2015, which is actually a flying interferometer. LISA (short for Laser Interferometer Space Antenna) carries two identical masses, 38 cm apart, and measures their distance with great precision using a small interferometer.
This measurement cannot distinguish gravitational waves, but it will allow scientists to understand the relative motion between the masses in space, measure various background noises and test new technologies. Depending on the results of the experiment, they will be able to plan the next project - LISA/eLISA, where three spacecraft will be millions of kilometers away from each other and together they will create a huge interferometer that will be able to measure gravitational waves.
The eLISA project was originally a joint program of the European Space Agency and the American agency (NASA), but in 2011 the Americans gave up their involvement due to budget considerations and the Europeans continued it alone, despite the delays and difficulties.
About two years ago, researchers from the BICEP telescope at the South Pole announced that they had measured evidence of gravitational waves in the cosmic background radiation - electromagnetic radiation in the microwave range (wavelength of a few centimeters) that reaches us from all directions in the sky. The background radiation was created about 400 thousand years after the big bang, with the formation of the first atoms from the elementary particles, and it is everywhere in the universe. According to the findings that aroused great interest in the physics community and the world media, the gravitational waves that resulted from the big bang created patterns in the polarization of the cosmic background radiation, which the researchers from BICEP measured.
Unfortunately, after a deeper analysis of the data, and measurements from another detector, it turned out that the changes in polarization were caused by dust particles in space whose influence was initially underestimated. Thus another announcement about the discovery of gravitational waves was shelved.
The great curiosity these waves arouse is not only due to the chance to confirm Einstein's prediction from a hundred years ago. Measuring gravitational waves will give us information about celestial bodies that do not emit as much electromagnetic radiation as visible light or radio waves, for example neutron stars or black holes. Gravitational waves will provide a fascinating glimpse into the physics of very strong gravitational fields, about which we currently know very little. "We are opening a new window to the universe," Reitza announced in a statement about the discovery. "The field of gravitational wave astronomy will allow us to see things we haven't seen so far."
The physicists especially hope that the measurement of gravitational waves will finally lead to the development of a unified theory: a system of equations that will connect gravity to the other three physical forces (the electromagnetic force, the strong nuclear force and the weak nuclear force), and will make it possible to explain most of the phenomena in the universe using one physical theory. This was the great ambition of Einstein and many other physicists in the 20th century and it remained the wish of physicists in the 21st century as well. Perhaps the ability to finally detect the elusive gravitational waves will bring scientists one step closer to realizing that dream.
Hagai Adri, PhD student in the Department of Physics of Complex Systems, Weizmann Institute of Science
The article was first published on the Davidson Online website of the Davidson Institute for Science Education
More on the subject on the science website - earlier this evening
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http://www.scientificamerican.com/article/lisa-pathfinder-reports-record-breaking-gravitational-wave-results/?WT.mc_id=SA_WR_20160608
may be…
right. I thought you were more intelligent…
miracles,
It would be highly recommended that you think before you respond,
So that there is no need to "leave it"....
may be…
Forget about it…
"Ebb and flow"?
A result of the pull of water in the direction of gravity...
that's it…
may be…
Think about tides - this is a movement that results from a daily change in the gravitational field of the moon (and the sun too, but it doesn't matter). This change is a very low frequency wave, but it is still a wave.
Miracles
"The movement of the moon causes a gravitational wave"?
What is ?
may be…
The movement of the Moon around us also causes a gravitational wave. In my understanding, what is interesting is that the waves travel at the speed of light - this was not confirmed before.
for my humble pleasure,
The discovery of gravitational waves may undermine the "complementary" theory
On the subject of the curvature of space and time...
And what causes the gravity waves to bend?
I don't understand what the excitement is about?
After all, it was clear that gravity exerts a force between two masses...
How can such a force act if not in waves?
I don't understand what the connection between gravity waves is
For the rest of Einstein's claims about the curvature of space and time...
Achilles, there is always the possibility that they were wrong and most of them there did not believe that the signal they received was real at first but they have a huge amount of devices that monitor both the system itself and the environmental phenomena that can affect their system, you can see all over the internet both in writing and directly in interviews to what depth They went in to calculate the various options that could affect the results of the experiment, unlike the experiment that was done at the South Pole that tested the indirect effect of polarization of light as a result of changes in the space-time of the universe, it was initially received with great skepticism by many scientists and from the tests they did later they realized that they were not successful to clearly show the phenomenon without the interference from the dust of our galaxy, even though this is not the end of the story also regarding the examination of the universe in this area, they and others will build a system that manages to remove the effect of the dust of our galaxy and then we can also get a clear picture and test the polarization of light, more One thing to remember is that today science is more accessible, faster and more transparent, if once the conversations of Einstein and his friends were largely the property of a small team of scientists, today the idea in the cafeteria reaches the public, which requires us to differentiate better how it works from the cafeteria to the theory to the proof
At what stage are we in this as well, there is debate among the scientists how much weight to give to the theory before it is proven, each according to his personal taste as the number of scientists, regarding their confidence in the proof, this also comes from the fact that they monitored anything they thought could affect their results, it took them months to do it because the signal was already there in September and also because the signal received corresponds amazingly to various parameters predicted in theories and simulations built during
many years including the time differences when the signal arrived at the two detectors so they even know the general area from which it came but it will be even better when more detectors of this type are covered,
Gravitational waves are very weak if only bodies with a huge mass in a change of state are able to create a wave that we can detect with our detectors,
It seems to me that you seem to be underestimating the abilities of the human race to understand the universe and to take advantage of its abilities from the moment of understanding
James Clerk Maxwell in the 18th century developed his electromagnetic equations, who would have believed that within decades Guglielmo Marconi would open the radio from the world of steam to the world of electricity, television, radio, mobile phone
It is possible from some remote village on Earth to speak directly to the International Space Station or to the home of each of us. It was really science fiction. Electricity is science fiction that exists today in every computer house from where I write the website where we communicate and respond. All these amazing things that we take for granted. This is a result. of millions or maybe billions of people working together and developing at a pace that is not linear, these are exponential, from the point of view of the world of science, there are already answers and there is already a demarcation
of some of the theories so that the understanding of the immediate science is very important in the coming decades they will build detectors that will probably be able to see to the first fractions of a second of the beginning of the universe It is an amazing thing that some human being only a few tens of thousands of years ago was not busy existing in a way that is not so far from the rest of our relatives like From a chimpanzee he reached such a deep understanding capacity as we have reached and we are only at the beginning
It seems that the confirmation that gives the Gushpanka for the detection of gravitational waves has been received.
At the exact same time when the gravitational waves were received on 15.9.15/0.4/XNUMX, the Fermi gamma-ray telescope received for XNUMX seconds short gamma rays that were apparently emitted from the same source (the collision of black holes causes the emission of gamma rays following the 'swallowing' of gases and plasma). Well, less than a week has passed and the story is starting to get more interesting than first thought.
For those who are interested, here is the link to the article by the team from Fermi:
http://gammaray.nsstc.nasa.gov/gbm/publications/preprints/gbm_ligo_preprint.pdf
to the skeptic
I agree with Nissim. The cold fusion is a bluff, any scenario
The conspiracy ignores that the entire world is hungry for clean energy
And in particular when a power like China buys oil and gas and pollutes itself knowingly,
It is no coincidence that it was precisely Chinese scientists who reached the temperatures
Nearing the feasibility of a hot nuclear fusion reactor.
Regarding the use of the discovery, I will remind you that the theoretical foundations
Einstein assumed the laser in 1916 - and even then not many people appreciated it
That within 100 years this theory will find applications like we have
Meet today.
The abilities that science is developing today (materials, computing, robotics),
At an increasing rate, it becomes difficult to predict
The development times of additional new capabilities.
Indeed, throughout history, wars have served as a technological catalyst
and scientific (the most prominent examples are of course the technologies
the nuclear and the rocket) today, when the superpowers manage
Wars through messengers, they invest less in progress
Technology - and there are still reasons for optimism even without wars
Global... like searching for new sources of energy
Or searching for minerals in space in the future.
I could not understand why Einstein showed that gravity is a distortion of
Time / space by a body with mass and deformation is the one responsible for attraction,
Thus he forgot that attraction is not exactly a force but a type of dynamic.
So what do you call the energy that the mass itself distorts space/time?
safkan
One of the reasons cold fusion doesn't get publicity is that it's a bluff.
Achilles
You're right. In recent years, physicists have adapted to the habit of publishing discoveries that have not gone through a serious testing phase. It seems to me that the reason for this is that they want to receive additional research budgets.
There has already been at least one case where gravitational waves were "discovered" and then it turned out that the "discovery" was wrong. The waves are so weak in strength that it is difficult to distinguish them from another disturbance (the article mentions this mistake)
neta,
This knowledge, whether true or not, has no practical effect on our lives: we will not be able to benefit from it in the foreseeable future (perhaps in another million years we will benefit from it).
On the other hand - I am outraged that infinitely safe discoveries of cheap energy from cold nuclear reactions receive zero exposure and scorn.. Cold nuclear energy reactors will enter public use probably within 10 years, they may gradually replace the entire energy production industry within (say) 50 years . The first nuclear reactor undergoes an annual field test for the purpose of its economic suitability for marketing, the test is probably going to end in March 2016. If the field test gives sufficient results - it will be applied to production and marketing immediately, if the field test does not give satisfactory results, the reactor will be redesigned so that its performances are more reliable, after the design Again there will probably be another extended field trial.
At the same time there is a prototype of a similar reactor that will generate electricity directly (without the need for turbines). At the moment its effectiveness is still unclear and it will be tested in the coming months. If the efficiency is sufficient, a nuclear reactor will be developed for domestic use that will be used for both heating and domestic electricity consumption: there is currently no timetable, but it is not for many years.
Such sensational news with so few reactions or resonance in the press. It's just sad and instructive about how ignorant we are.
a question
Is there a hypothesis or a measurement of the propagation speed of gravitational waves in the space of the universe (on the one hand the wave 'creates' the space and perhaps the definition 'moves in it' is not accurate but on the other hand the claim in the reports that this is a measurement of a wave that came from an event in the universe that happened a given time ago)?
An interesting thought occurred to me and I would love to hear reasoned responses: what if there are not four forces and a curved space as a result of mass, but rather three forces (electromagnetic, strong and weak nuclear) and a curved space whose topography is gravity in and of itself? According to this, the aforementioned gravity waves, if they exist, are actually undulating oscillations that pass through the fabric of space itself, when the oscillation is perhaps also in higher dimensions than the dimensions in which we are "stuck"? Gravity is a weak force and difficult to measure because the curvature of space is minimal. I wonder if this is nonsense at Alma or if I deserve a Nobel Prize.
An interesting thought occurred to me and I would love to hear reasoned responses: what if there are not four forces and a curved space as a result of mass, but rather three forces (electromagnetic, strong and weak nuclear) and a curved space whose topography is gravity in and of itself? According to this, the aforementioned gravity waves, if they exist, are actually undulating oscillations that pass through the fabric of space itself, when the oscillation is perhaps also in higher dimensions than the dimensions in which we are "stuck"? Gravity is a weak force and difficult to measure because the curvature of space is minimal. I wonder if this is nonsense at Alma or if I deserve a Nobel Prize.
Nonsense, until they completely understand whether light is a wave or a particle, then all the speculation embodied in the study of the interference phenomenon has no validity
I did not understand if the translation of the event of the collision of two black holes is decoded
Only by LIGO or also by other means of observation?
It is interesting to cross-reference the events that will be discovered in the future with electromagnetic radiation
which comes from the same direction with the same varying intensities and parallel wavelengths
to gravitational waves.
It is interesting if it is possible, for example, to "see" the orbit of Saturn or the Sun or
Any other factor whose gravitational waves are strong enough, on top of the new platform
this one? Or it mostly detects events that start with "gravity signature"
that the shape changes sharply?
Even as there is gravitational attenuation for light rays (and maybe also for the rest of the spectrum?),
So does or how does gravitational repulsion into gravitational waves happen?
The more I read, the more I am amazed that they have already rushed to declare the discovery valid. The fact that two detectors at a distance of 3000 km from each other detected a similar pattern of fluctuations at a certain time still does not particularly convince me (has the possibility of seismic effects or magical events been ruled out, for example?) and in particular that the event took place at a huge distance of 1.3 billion light years. I would expect to see results from closer sources such as the Virgo supercluster which is "only" 100 million light years away. In any case, estimates speak of the discovery of two similar phenomena a year, and now with the more sensitive systems there may be something wrong. The problem is that the people of LIGO will be quick to declare a discovery already valid, they how to say, 'stepped the gun before the deadline'.
The irony is that in 1936 Einstein himself doubted the existence of gravitational waves and justified his claims in an article with Natan Rosen under the title "Do gravitational waves exist at all?" The editors of The Physical Review rejected the article and it was eventually published in the Journal of the Franklin Institute. Under a softer title "On Gravitational Waves"