Talk:Laser Interferometer Space Antenna

Naming

Laser Interferometer Space Antenna is the proper name, with LISA as an abbreviation. --Ng.j (talk) 15:45, 18 November 2007 (UTC)

Following NASA leaving the partnership with ESA, the proposed mission named was changed to New Gravitational-wave Observatory (NGO), or informally evolved Laser Interferometer Space Antenna (eLISA). Following the failure of NGO to be selected for the L1 mission in 2012, the historical name of LISA has been readopted. LISA will be used as the base for the name for the collaboration and for the family of space based gravitational wave detectors which share components of the design. This maintains the legacy of previous work and makes the connection with LISA Pathfinder. The revised LISA-like mission design proposed as NGO will now be referred to as eLISA. BobQQ (talk) 21:00, 27 June 2012 (UTC)

See discussion here for more details: Wikipedia:Redirects for discussion/Log/2014 April 9#Several redirects to Laser Interferometer Space Antenna — BobQQ (talk) 08:38, 17 April 2014 (UTC)

Interferometers

I looked back at the ESA data, which states "The two assemblies on one spacecraft point towards an identical assembly on the other two. In this way, the three spacecraft form two independent Michelson interferometers, providing redundancy.". The wiki article however, states "This forms three complete (but not independent) interferometers, with each arm being part of two interferometers". Not sure if this is a misunderstanding on the part of the original author, or what. I'm changing the article text to reflect the the ESA fact sheet for now. --Astrobit (talk) 03:42, 17 April 2008 (UTC)

LISA will be a Michelson interferometer. As everybody knows, Michelson interferometers do not produce any results, as light has the same speed in any direction, no matter how compressed space is. I dare to predict that this will happen with LISA too: When a gravitational wave comes, it will not only compress the space between the satellites but also the light waves. Thus the number of light waves between 2 satellites will remain exactly the same as without the gravitational wave and no signal will be seen. Can anybody explain to me why this should not be so? Joe Crasy (talk) 07:50, 22 October 2008 (UTC)

Your comments about the Michelson interferometer apply only to inertial (constant velocity) frames. In non-inertial frames and under the effects of gravitation, the speed of light may be measured to change. It is generally considered that the sped of light is constant and the lengths of physical objects are distorted by gravity waves. Martin Hogbin (talk) 14:52, 22 October 2008 (UTC)

These arguments are not convincing at all. Light is also a "physical object" and thus gets distorted by gravity waves too. According to Einstein, a moving object gets compressed in the direction of movement. If that compression could be measured with light waves on the moving object, the Michelson interferometer would produce a signal. But it does not!

I can only reply that, according to general relativity, which is the theory that predicts the existence of gravitational waves, LISA would be expected to produce an output in the presence of such waves. Martin Hogbin (talk) 09:02, 27 October 2008 (UTC)

I hope you realise that this is a very weak argument: General relativity predicts the existence of gravitational waves, it does not predict that LISA will produce a signal. Joe Crasy (talk) 19:40, 16 November 2008 (UTC)

The idea is, that you vary the length of one of the arms from the Michelson-Interferometer by stretching it through a gravitational wave. The other one remains with its beginning length and therefore you'll get an interference pattern. Through the regular formulas one can then calculate the exact length and therefore get the results needed. Der Overmind (talk) 11:29, 7 May 2018 (UTC)

Other Ground based Detectors

Any mention of POLARBEAR? http://ucsdnews.ucsd.edu/newsrel/science/03-07Telescope.asp —Preceding unsigned comment added by 128.54.78.13 (talk) 03:21, 12 March 2008 (UTC)

Countdown clock

Is this possible in Wikipedia? It would immediately make this article come alive.Serbian Defense Forces (talk) 07:16, 27 January 2009 (UTC)

Terminated?

Apparently terminated, as NASA+ESA; similar to continue, just ESA? 94.30.84.71 (talk) 19:00, 19 April 2011 (UTC)

We (user Tlamatini and I) went ahead and modified the article to reflect the apparent termination of NASA's participation, as expressed in this NASA news release: http://lisa.gsfc.nasa.gov/cosmic_vision_changes.html. We hope the edit holds up to Wikipedia's style and guidelines, and that it is written in proper english. Meithan (talk) 03:50, 5 May 2011 (UTC)

revamp of article

Had to rewrite most of the article, as information was severely outdated. Basically the sections up to the "science" section are new, although I tried to keep as much of the old text and references as was possible.

The rest of the sections will follow shortly.

Re Naming: I am aware that LISA went to eLISA. At this time information about eLISA got put here also, but a new article on eLISA is in the pipeline, and the information will we separated. JRiegerMM (talk) 09:10, 18 November 2013 (UTC)

Name?

Is there any basis form naming this article "Evolved Laser Interferometer Space Antenna"? My understanding is that the meaning of the "e" in "eLISA" is kept purposefully vague. It could stand for "evolved" or for "European" or for something else entirely. The elisa website [www.elisascience.org] conspicuously never mentions any meaning of the eLISA acronym. Should the page be renamed to eLISA?TR 07:59, 8 September 2015 (UTC)

Hello. It stands for "evolved". See: [1], [matteronline.xyz/blog/2015/08/31/evolved-laser-interferometer-space-antenna-new-gravitational-wave-observatory/], [2], [3], [4], [5]. Cheers, BatteryIncluded (talk) 15:51, 8 September 2015 (UTC)

That proves only some people refer to it that way. Much more importantly, the eLISA consortium goes out of its way to be unspecific. The eLISA whitepaper [6] does not contain the word "evolved" even once. You will also not find the term "evolved LISA" anywhere on the website of the eLISA consortium. They do however repeatedly say that the mission is named "eLISA". I think the eLISA consortium trumps a bunch of blog posts.TR 16:22, 8 September 2015 (UTC)

Is this a blog?: http://adsabs.harvard.edu/abs/2013AAS...22115305S -BatteryIncluded (talk) 16:27, 8 September 2015 (UTC)

Hello. This is the Mission Home Page, and they do call it "evolved LISA": https://www.elisascience.org/multimedia/video/gravitationaluniverseisl3video -Cheers, BatteryIncluded (talk) 16:35, 8 September 2015 (UTC)

Yay you found somebody slip up. Much more relevant is that in the official eLISA/Gravitational Universe whitepaper [7] the following is said:

The mission (which we will refer to by its informal name “eLISA”) will survey for the first time the low-frequency gravitational wave band...

This is inline with what scientists involved in the proposal have told me. After NGO was not selected, the name NGO was dropped and "eLISA" was general adopted as the name for the gravitational universe's strawman mission without any particular meaning associated to the acronym. From time to time you will find people referring to the "old" meaning, but there is no "official" meaning of the acronym.

(Well, technically the there is no official "eLISA" proposal to begin with. ESA has accept "The Gravitational Universe" as the theme for its L3 Cosmic Vision mission. Hereby, ESA has commited itself to lauch a mission to detected gravitional waves in space. It has not been decided that this should be a giant interferometer ala eLISA. In theory, it could be a completely different design based on different physics. A formal call for a design proposal will be made by ESA in due time. In the meantime there is no "eLISA" proposal, and hence no "official" name.)TR 11:44, 9 September 2015 (UTC)

Wrong graphic

The graphic in paragraph "science" is wrong. Nevertheless, the reference is good a points to the good graphic (which is different eLISA and LISA do not work at the same frequency).

The reference points to this : "http://rhcole.com/apps/GWplotter/#redirect" — Preceding unsigned comment added by 88.167.33.242 (talk) 09:09, 14 February 2016 (UTC)

Phase or frequency difference?

The article says: Practically, LISA measures a relative phase shift between one local laser and one distant laser by light interference. Comparison between the observed laser beam frequency (in return beam) and the local laser beam frequency (sent beam) encodes the wave parameters. I am unable to interpret this. Superficially it seems it says that a difference in phase is measured by measuring a difference in frequency. which seems paradoxical. Do we really need the expression wave parameters here? --Ettrig (talk) 12:30, 13 October 2020 (UTC)

eLISA?

What is eLISA? How is it different than just LISA? It's mentioned a few times in the article but never explained. --Yarnalgo _talk 01:06, 15 June 2021 (UTC)

It's a name used in the past. When LISA was first proposed to ESA's Cosmic Vision L1 mission, it was called 'LISA', with three spacecrafts and three arms (the laser between each spacecraft). Then, funding issues forced the proposal team to simplify the proposal; while retaining the three spacecraft configuration, the number of arms was reduced to two. LISA was renamed as the New Gravitational wave Observatory, or 'NGO'. NGO wasn't selected by ESA (they selected a Jupiter probe), and the design reverted to using three spacecraft and three arms. This 'eLISA' proposal competed for the Cosmic Vision L2/3 mission. By the time this proposal was chosen by ESA, however, it was simply called LISA again. Kind regards, Hms1103 (talk) 06:16, 29 June 2021 (UTC)

Cleaning up the opening section

Some of the historical wrangling over the project between ESA and NASA is quite outdated. It's relevant to the history section, but putting it in the opening paragraph obfuscates the current status of the project. I think it should be removed, and merged into the history section. LazyAstronomer (talk) 11:05, 29 June 2023 (UTC)