linus tech tips gravity waves.. 6000

[killerbee04x]

people bullshit science when they can. its politics.. they don't want to live on the street. they need funding the keep the project going..  the gravity detectors never worked. the earth vibrates.. the plates are always on the move and so much more.. so what does it really detect? well if you look at their locations.. they are all connected to a nuclear power plant. They project ultra big waves that bounce off the atmosphere. giving the USA 3d radar for missile defense.. just look at where they are all located. if it was to detected gravity waves they would be deployed 3 dimensionally on earth and one in space.. They are deployed for missile defense. no other radar goes as high as these things can. what up with the LONG LASER? ITS TO KEEP THE DISH IN LINE FROM VIBRATIONS. like how different shapes make different sounds. you have to have a perfect shape to collect information and receive information. its just a senor.. not a gravity detector. The gravity detection didn't even happen at the dish.. the information what programed into a computer before hand.. it like space was a perfect medium. like we don't have a asteroid belt around are solar system. there not random objects we can't detect flying around are solar system and the next. these people played him good.. if feel sorry for him. SO THEY PREPROGRAMED THE DATA. THEY THEN USED A MEDUIM TO SAY ANYTHING NOT WITHIN NORMAL BACK GROUND VIBRATIONS IS A GRAVITY WAVE.. THEY CAN ONLY MEASURE EVENT AT ARE SLOWER THEN GRAVITY.. LOL THAT LASER CAN'T DETECT ANYTHING MOVEING AT LIGHT SPEED LET ALONE FASTER.. The ping sent back is so small its like trying to hear someone talking in a different solar system.. way to much background interference.. over lapping sounds and so much more.. its impossible. HEY WE GOT OUR DEFENSE SYSTEMS FUNDED for us all... 

 

[killerbee04x]

you need 3 sensors on earth.. you need one in space... to detect gravity waves above background noise.. lol.. me any many other don't believe the cult politic nonsense of gravity wave detection. 

 

[killerbee04x]

once you got that you can build a net..

[KarathKasun]

So many basic physics principals missed by thus guy that I cant even.

[KuJoe]

Why are you so mad at science? You should smile more.

[tikker]

Alright, I'll take the bait First of all, this video is about gravitational waves which are technically not the same as gravity waves. The former are created by accelerated masses and can only be detected significantly from massive objects such as neutron stars and black holes. Gravity waves are just your every day waves you can see in the ocean, for example.

 

Now let's move on to using only 2 stations in stead of 3. You are partially correct here in that to start pinpointing an exact location, we would need three or more detectors. Scientists know this, which is why they are planning to build more. However using the combined knowledge of two stations and the dead zones (i.e. zones where the detectors are not sensitive or not sensitive enough), we can estimate an approximate location by e.g. saying we are 90% sure the even happened in this general area. This is then used by follow up telescopes. This area is much larger than the typical area covered by normal telescopes however, which illustrates again the need for extra stations, as this makes it extremely difficult to do a quick enough follow up, since we don't exactly know where to look. An example of this is shown in the following plot. The circle is the sky in a spherical projection. Hours indicate right ascension, which is a horizontal, and the degrees indicate declination, which is a vertical coordinate, if you will. The gray fuss is the Milky Way. Solid black lines inidicate the most probable area of the depicted event from gravitational waves and the other symbols (squares and circles) separately the field of view of telescopes at other wavelengths, and combined the area covered for follow up. It's taken from here: https://www.ligo.caltech.edu/news/ligo20160404 which is a nice read about why more detectors are necessary.

 

 

Third, your point about vibrations from buildings, vehicles, earthquakes or whatever. The video already explained the measures they take to eliminate as much of the Earth based vibrations as they can. Furthermore, if you see a signal in only one of the stations or the timing for the signal between the stations is off from what you would expect, this can be eliminated as a gravitational wave. Here lies a big part of the power why we can do this: we can exactly calculate what the signal should look like based on general relativity. This is done for a variety of scenarios, and then something called "template fitting" is done, in which the signal is compared to a large database of template events to find the best match. This match can then be further inspected to make absolutely sure, but a having match is already a good sign something happened.

 

Finally your comment on the speed of light. Laser light moves at, you guessed it, the speed of light. So if anything can detect something moving at light speed, it's lasers. In any case, gravitational waves travel at the speed of light. This means we can exactly predict what the delay between the two detectors in Livingston and Hanford should be. In other words, if we detect a signal at A, we know the same signal has to arrive at B precisely X nanoseconds later. This is the first "line of defense" so to speak, if it does, continue with template fitting to see if we can match it. Finally, nothing can or will ever move faster than the speed of light in vacuum. It's the cosmological speed limit.

 

So in short, detecting gravitational waves is very much possible nowadays and can be done with only two detectors on Earth. Yes more is bettter, yes bigger is better, yes going to space will be better (and is being worked on, e.g. eLISA), but it's by no means impossible anymore. As a side note, it is possible to recover signals from below the noise floor. Things like GPS rely on it, for example, but that's besides the point here.

[Tarun10]

This could be possible with Trump that the Interferometer could be used to detect other things like earthquakes but as RADAR??? I mean they can't use Laser for that. And Long Range radar fired into the clouds?? They could use the dozens of military satellites they already have for it. There has been question of the accuracy of the observations due to interference form local pollution, traffic, etc. We need a third observatory to disprove critics of Einstein's theory and to be very very sure. 

Also the speed of the leasers doesn't matter nor does the speed of the gravitational waves. The gravitational waves disrupt spacetime ever so slightly which affect the distances between mirrors and detector slightly causing changes in the detected laser beam. This idea would work with anything moving at a constant speed from one end to another but its easier to split the laser and then rejoin it to note the difference and also to reflect it.

[Tarun10]

6 minutes ago, tikker said:

. Finally, nothing can or will ever move faster than the speed of light. It's the cosmological speed limit.

Edit: faster than the speed of light in pure vacuum. 

Also I don't understand what that picture represents, a short explanation would be helpful.

[r4tch3t]

29 minutes ago, killerbee04x said:

 

Lol armchair scientist. So much effort that could've gone into actually learning the science. 

Based on your rant you have no clue how these things work. Please learn the science on how these work before telling the world of conspiracy theorys. And if you're going to claim its something else, provide proof. If you say it projects ultra big waves that bounce off the atmosphere, show us some measurements of this proving that LIGO was the source.

[Tarun10]

2 minutes ago, VegetableStu said:

the laser tunnels contains an emptier-than-orbital-space vacuum ._.

So laser should be faster in the LIGO than in outer space??

[tikker]

12 minutes ago, Tarun10 said:

Edit: faster than the speed of light in pure vacuum. 

Also I don't understand what that picture represents, a short explanation would be helpful.

I've added a bit of explanation for the various things in the plot and the vacuum clarification.

6 minutes ago, Tarun10 said:

So laser should be faster in the LIGO than in outer space??

Oribtal altitude is hardly outer space There are various explanations around as to why light slows down, but it comes down to interactions with the medium, so yes technically it may be a tiny tiny tiny but negligible amount "faster" in the detectors.

[Nicnac]

thanks for the in-depth explanation @tikker

[tikker]

11 minutes ago, VegetableStu said:

the laser tunnels contains an emptier-than-orbital-space vacuum ._.

Space really is hardly empty if you think about it. It's like one atom per cm3 in interstellar space if I remember.

[Guest]

1 minute ago, Tarun10 said:

So laser should be faster in the LIGO than in outer space??

Theoretically, yes. 

4 minutes ago, r4tch3t said:

Lol armchair scientist. So much effort that could've gone into actually learning the science. 

Based on your rant you have no clue how these things work. Please learn the science on how these work before telling the world of conspiracy theorys. And if you're going to claim its something else, provide proof. If you say it projects ultra big waves that bounce off the atmosphere, show us some measurements of this proving that LIGO was the source.

Don't be so critical of others. It's simply rather a different way of thinking. It's one thing to have a point of view, and to try and back it up, but to immediately dismiss someone's view is ignorance. It may be misplaced, but there is some credit to what he is talking about, and a fresh view is always welcome. 

 

[Tarun10]

1 minute ago, RorzNZ said:

Theoretically, yes. 

Don't be so critical of others. It's simply rather a different way of thinking. It's one thing to have a point of view, and to try and back it up, but to immediately dismiss someone's view is ignorance. It may be misplaced, but there is some credit to what he is talking about, and a fresh view is always welcome. 

 

I guess you should respect opinions but you can't let that cloud your common sense sometimes. Besides you are a biologist who knows about astrophysics??

[Guest]

1 minute ago, Tarun10 said:

I guess you should respect opinions but you can't let that cloud your common sense sometimes. Besides you are a biologist who knows about astrophysics??

Common sense is to listen to what they say, and the message they are portraying. Its simple comprehension you get used to reading papers. 

[Tarun10]

Just now, RorzNZ said:

Common sense is to listen to what they say, and the message they are portraying. Its simple comprehension you get used to reading papers. 

I mean you respect people's opinions and listen to it but if someone is telling you the world is tomorrow you shouldn't believe it immediately unless you confirm it with another source. I worded my statement wrong.

[Guest]

8 minutes ago, Tarun10 said:

I mean you respect people's opinions and listen to it but if someone is telling you the world is tomorrow you shouldn't believe it immediately unless you confirm it with another source. I worded my statement wrong.

Theres plenty of cited baloney papers out there. Bullshit makes the world go around, thats for sure, if you choose to be a scientist its literally your job to sift through it. 

[KarathKasun]

If you really want to make someone's head spin, we could go into the argument that the speed of light is not strictly constant.  Its a function of the curvature of space-time.  Gravity impacts it due to local time moving forward at a different rate near a gravity well.

 

A second is not the same here as it is in orbit for example.  And speed is measured in distance per unit of time.

[GoldenLag]

49 minutes ago, Tarun10 said:

So laser should be faster in the LIGO than in outer space??

No it moves at c. (Aka the speed of light in a perfect vacuum) and light allways moves at c. It can hovever hit particles which causes it to take longer to move through a substance. The light itself never stops moving at c. That is why they try to eliminate any particles interfiering with the light. 

 

Sidenote: vacuum in outer space isnt a "true vacuum". You will particles around, but there arent awfully many, but its too many for Ligo to make accurate measurements. 

 

Spaceprobes like satalites in low earth orbit and the ISS needs regular boosts to not go suborbital due to the effects of drag. While the drag is minescule, its still there. (The drag comes from particles from earths athmospere which technically still excists up there, but to no meaningfull effect)

[Tarun10]

26 minutes ago, KarathKasun said:

If you really want to make someone's head spin, we could go into the argument that the speed of light is not strictly constant.  Its a function of the curvature of space-time.  Gravity impacts it due to local time moving forward at a different rate near a gravity well.

 

A second is not the same here as it is in orbit for example.  And speed is measured in distance per unit of time.

So you are saying that gravity curves spacetime which means a second is essentially much longer where gravity is less?? Is this related to time dilation in anyway??

[GoldenLag]

26 minutes ago, KarathKasun said:

we could go into the argument that the speed of light is not strictly constant.

Except afaik i know it is. That is with relativity taken into account. Because time dilation is a thing.

 

28 minutes ago, KarathKasun said:

A second is not the same here as it is in orbit for example.  And speed is measured in distance per unit of time.

While this is true, the speed of light doesnt change. Due to relativity and depending on who is observing you will observe things differently. However, the constant of the speed of light is kept. Its an issue if you want to use accurate clocks like in Ligo, but there are ways to take into account for timedilation. It has been done for quite a while with GPS satalites that wouldnt work properly without compensation due to timedilation (im not 100% shure that is the correct term)

 

 

The gravity waves allways moves at the speed of light, the reason why we use light to measure these is due to destructive interfierense and the fact we know what the speed or light is (to a stupidly high accuracy). These tyings allow use to measure and detect if on of the "arms" are slightly longer or shorter due to waves passing through. These detections are only possible because wr use 2 arms as 1 arm would neher see the effect of a wave

[tikker]

32 minutes ago, VegetableStu said:

the laser tunnels contains an emptier-than-orbital-space vacuum ._.

Hmm, let's do a back of the envelope calculation. Let's assume room temperature for both LIGO and low Earth orbit, T = 293 K (temperature is hard to define in a vacuum, but for argument's sake) and the ideal gas law (super low pressure, so not so unreasonable) P*V = N*k*T

 

For ISS

According to this article the presure in low Earth orbit is P~10^-7 Torr = 133 * 10^-7 Pa, giving N~10^15 particles/m3.

 

For LIGO

Taking the pressure in the tubes from the LIGO page P = 10^-9 torr = 133 * 10^-9 Pa, which gives a particle density of N~3.3*10^13 particles/m3; effectively N~10^-13 particles/m3 (mostly hydrogen).

 

So, as the difference in pressure already told us, there's probably about a factor 100 times fewer particles in the LIGO tubes than around the ISS

 

1 hour ago, Tarun10 said:

So laser should be faster in the LIGO than in outer space??

Only minimally so though, the difference in index of refraction between vacuum and air is already just 0.03%, which is a large difference in pressure/density. So the speed of light shouldn't be that much different between LIGO and space, but it is taken into account.

[TechyBen]

1 hour ago, killerbee04x said:

you need 3 sensors on earth.. you need one in space... to detect gravity waves above background noise.. lol.. me any many other don't believe the cult politic nonsense of gravity wave detection. 

 

I'm not feeding the trolls. I'm helping other people learn.

 

You can detect movement with 1 sensor. They are not detecting "waves", they are detecting "movement". *Something* moved the instruments, 2 of them, and that can only be a thing we label/name "gravity waves". You can show that these are other things, but they certainly exist as a "thing".

[GoldenLag]

4 minutes ago, Tarun10 said:

So you are saying that gravity curves spacetime which means a second is essentially much longer where gravity is less?? Is this related to time dilation in anyway??

This is a thing, yes. Though again, constants are preserved. If you ask someone moving at 99.999999% of the speed of light to measure the speed of a photon. They will find it moving at the speed of light relative to them. (Im using tume dilation due to speed as an example as using massive bodies like black holes is way harder to explain)

 

Waved curve spacetime whoch is why they are stupidly hard to detect. This is because that any ruler will get "stretch" and "contract", without any notice for an observer looking at the ruler.