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This month the laser at Magurele, Romania became the most powerful laser in the world, according to various sources.

Related: Is the laser built in Măgurele, România, the most powerful in the world?

Digi24, a Romanian news and television company mentioned:

Laserul Institutului de fizică nucleară de la Măgurele a atins cea mai mare putere din lume, echivalentă cu 10 procente din cea a Soarelui şi încă nu este la capacitatea maximă.

Translated:

The laser of the Nuclear Physics Institution at Magurele reaches the highest power in the world, equivalent with 10 percent of that of the Sun, and it’s not yet at its highest capacity.

Is that true? How did the scientists calculate that the laser is 10% of the power of the Sun?

jdunlop
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Ionică Bizău
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    I don't speak Romanian but do they mean 10% of the energy output of the sun, which in one hour exceeds the entire energy consumption of the whole plant for a year, or do they mean 10% as bright as the sun measured at some specific distance from it (e.g. at the surface)? – dont_shog_me_bro Mar 19 '19 at 14:22
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    @dont_shog_me_bro I suspect that the answer to the question you pose in your comment is also the answer to the question "how did scientists calculate...?" (Ionică Bizău: it is too few characters for me to propose as an edit, but *calculate* should be a bare infinitive, without *-d).* – phoog Mar 19 '19 at 14:49
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    Do bear in mind that most high-powered lasers "fire" for a very brief period of time, discharging energy that they have stored up over a much longer period of time. – Daniel R Hicks Mar 19 '19 at 16:41
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    This would almost certainly be a better fit for our physics site. – DJClayworth Mar 19 '19 at 16:48
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    It all depends how we compare things. A single cigarette lighter can release much more energy then the Sun, per volume. Thins meas that a cigarette lighter releases more energy while it burns than a similarly sized chunk of the Sun in the same time. – vsz Mar 19 '19 at 18:02
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    Definitely better at Physics since there doens't seem to be a reason to be skeptical of multiple sources with no dissenting ones. – CramerTV Mar 19 '19 at 18:55
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    @dont_shog_me_bro: 10% of the sun's power output sounds more reasonable when you consider the laser only does so for a few picoseconds or so at a time. – whatsisname Mar 19 '19 at 20:56
  • @vsz - You don't need a cigarette lighter. A warm compost pile puts out a lot more power per volume than does the Sun. The Sun: 0.2725 watts per cubic meter. A warm compost pile: over 300 watts per cubic meter. Even if one narrows the Sun down to the central core (the only part that generates energy), the warm compost pile still wins in terms of power per unit volume. – David Hammen Mar 20 '19 at 10:10
  • I would guess they mean sun output of a circular cross section of same size as laser circular area cross section. – mathreadler Mar 20 '19 at 13:05
  • @dont_shog_me_bro Do you mean that the sunlight *that falls on the Earth* in one hour exceeds the energy consumption of the planet for a year? – Acccumulation Mar 20 '19 at 16:34
  • @Acccumulation indeed, if it could somehow all be harvested and we could live in darkness for an hour (easier for those who are on the night side of course). – dont_shog_me_bro Mar 20 '19 at 17:08
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    @CramerTV and DJClayworth, the claim itself is perfectly valid for Skeptics, I think. The "how is it calculated" part is actually part of how it should be answered and shouldn't be taken as a Physics question. The question isn't how the laser works, but whether the claim makes sense. That's Skeptics territory. – Mast Mar 21 '19 at 05:53
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    Besides, don't migrate something that's perfectly on-topic where it is. – Mast Mar 21 '19 at 05:54
  • @dont_shog_me_bro The output of the sun during 2 µs already exceeds the Earth's yearly consumption. You probably meant the insolation on Earth, not the output of the sun. – Eric Duminil Mar 21 '19 at 08:10
  • @EricDuminil I didn't mean anything, I was speculating on what they meant. – dont_shog_me_bro Mar 21 '19 at 08:55
  • @dont_shog_me_bro : I was referring to "10% of the energy output of the sun, which in one hour exceeds the entire energy consumption of the whole plant for a year,", which you wrote AFAICT. – Eric Duminil Mar 21 '19 at 09:10
  • @EricDuminil it's true either way, 2us is < 1 hour – dont_shog_me_bro Mar 21 '19 at 09:22
  • @dont_shog_me_bro well played. ;) – Eric Duminil Mar 21 '19 at 09:53

2 Answers2

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It's possible they are actually talking about the rate of energy given off by the Sun that reaches the Earth. However, they are not talking about the amount of energy released, but rather the rate of energy released.

The "laser at Magurele, Romania" is actually part of the Extreme Light Infrastructure, a pan-European research project, described by Wikipedia as

...a laser facility that aims to host the most intense beamline system worldwide, develop new interdisciplinary research opportunities with light from these lasers and secondary radiation derived from them, and make them available to an international scientific user community.

According to the Wikipedia article, on 13 March 2019, the ELI NP Research Centre, which is the facility located in Magurele, released a communication regarding the results of a demonstration test.

On March 13, 2019, Magurele held the public communication of the ELI-NP high-power laser system test results, which was also a demonstration test, confirming the achievement of the power of 10 [Petawatts].

A Petawatt is the equivalent of 1,000,000,000,000,000 (15 zeroes), or 10^15 Watts, as the prefix Peta describes. Therefore, a 10 Petawatt laser would be a 10x10^15, or 10^16 Watts.

Per this report from Sandia National Laboratories, they calculate the amount of solar power that reaches the earth's surface as 89,300 Terawatts.

A Terawatt is the equivalent of 1,000,000,000,000 (12 zeroes) or 10^12 watts. A Petawatt is equal to 1,000 Terawatts, so you can easily convert between the two by dividing the number of Terawatts by 1,000 to get the number of Petawatts. Therefore, the amount of solar power hitting the Earth in Petawatts is 89.3 Petawatts.

Dividing the output of the ELI-NP laser test by the energy output of the Sun that reaches the surface of the Earth results in

10 Petawatts / 89.3 Petawatts = 11.198%

which is approximately 10%. Note however, that this does not mean that the laser is continuously generating 10% of the sun's energy. Per the Wikipedia article on Watt

[The Watt] is defined as a derived unit of 1 joule per second,1 and is used to quantify the rate of energy transfer.

Further down, the page has a section on the distinction between "Watts" and "Watt-hours".

The terms power and energy are frequently confused. Power is the rate at which energy is generated or consumed and hence is measured in units (e.g. watts) that represent energy per unit time.

For example, when a light bulb with a power rating of 100W is turned on for one hour, the energy used is 100 watt hours (W·h), 0.1 kilowatt hour, or 360 kJ. This same amount of energy would light a 40-watt bulb for 2.5 hours, or a 50-watt bulb for 2 hours.

Power stations are rated using units of power, typically megawatts or gigawatts (for example, the Three Gorges Dam is rated at approximately 22 gigawatts). This reflects the maximum power output it can achieve at any point in time. A power station's annual energy output, however, would be recorded using units of energy (not power), typically gigawatt hours. Major energy production or consumption is often expressed as terawatt hours for a given period; often a calendar year or financial year. One terawatt hour of energy is equal to a sustained power delivery of one terawatt for one hour, or approximately 114 megawatts for a period of one year.

Typically, these kinds of experimental lasers are not constantly on, and fire for an extremely short period of time. Per the article on the National Ignition Facility, a facility with a similar, albeit less powerful laser

NIF aims to create a single 500 terawatt (TW) peak flash of light that reaches the target from numerous directions at the same time, within a few picoseconds.

A 10 Petawatt laser fired for a single picosecond would consume

10^16 Watts * (1 / 10^12) seconds = 10,000 Watt-seconds

10,000 Watt-seconds / 3,600 (seconds/hour) = 2.78 Watt-hours

Compare this number to the energy consumption of the world which was approximately 22 Terawatt-hours in 2017, and the amount of energy consumed by this laser is completely insignificant, accounting for less than a trillionth of the world's energy consumption.

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DenisS
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    Why do you even focus on the energy? It is not mentioned anywhere in the question, or in any of the linked articles. You can remove the second half of the answer and make it clearer. – pipe Mar 19 '19 at 15:50
  • Note that the SI names of these units are *watt*, *terawatt*, and *petawatt*, without hyphens or uppercase letters. – GentlePurpleRain Mar 19 '19 at 16:35
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    @pipe the second part is in there because of the common mistake of conflating power with energy. Just because the laser is reaching 1/10th of the Sun's power doesn't mean it's dimming lights all over the planet. – DenisS Mar 19 '19 at 16:50
  • @mast3rd3mon did I mess it up somewhere? Please point it out and I'll fix it, thanks :) – DenisS Mar 19 '19 at 16:50
  • @GentlePurpleRain fixed – DenisS Mar 19 '19 at 16:50
  • it could just be me... in the section starting `Per this report...`, 89,300 Terawatts hits the surface, then `Converting the Terawatt into a Petawatt is as simple as dividing by 1,000, therefore the amount of solar energy hitting the Earth in Petawatts is 89.3 Petawatts`, surely they should be swapped over? so: `89,300 Petawatts hits the surface` and `Converting the Petawatt into a Terawatt is as simple as dividing by 1,000, therefore the amount of solar energy hitting the Earth in Terawatts is 89.3 Terawatts`? – mast3rd3mon Mar 19 '19 at 16:53
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    @mast3rd3mon maybe i should have phrased it differently, saying 1000 TW = 1 PW. I'll rethink how i'm phrasing that and make an edit. – DenisS Mar 19 '19 at 16:54
  • the edit now makes sense, sort of, `...Terawatts by 1,000 to get the number of Petawatts` should be `...Petawatts by 1,000 to get the number of Terawatts`, i also have a feeling that some numbers somewhere are wrong, as 89.3 Petawatts is the same as the sun's supposed power of 89,300 Terawatts – mast3rd3mon Mar 19 '19 at 17:01
  • @mast3rd3mon right, a TW is 1/1000th of a PW, so you need to divide the TW by 1000 to get the PW. I converted the units in order to actually compare the two numbers, since my source on the Sun uses TW and the laser is measured in PW – DenisS Mar 19 '19 at 17:04
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    DenisS - Nice answer. +1. || Just "for completeness". The rest of your answer shows that you know this but, your statement "... Note however, that this does not mean that the laser is generating 10% of the sun's energy ..." is incorrect. Change to eg "*continuously* generating" and it is correct. Power is energy per time (as you know). While it is operating, the LASER **IS** generating 10% of the sun's energy". - Actually, based on another answer, = "10% of the Sun's energy that falls on the outer atmosphere of the earth" - but, again, only during the time that the LASER is lasing. – Russell McMahon Mar 20 '19 at 02:56
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    @mast3rd3mon You would multiply the number of petawatts by 1000 to get the number of terawatts. – user253751 Mar 20 '19 at 07:08
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    Ah, so a laser that can produce energy at a tremendous rate, for a tremendously short amount of time, is very powerful - according to the strict definition of power. – Grimm The Opiner Mar 20 '19 at 08:13
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    OTOH, the energy output of the sun is _not_ 89.3PW. 89.3PW is only the energy reaching Earth, which is an infinitesimally tiny fraction of the sun's _total_ energy output. 89.3PW isn't even enough to qualify as a rounding error in the sun's total energy output. – Dave Sherohman Mar 20 '19 at 09:22
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    @DaveSherohman - Correct. The Sun's luminosity is 384.8 yottawatts, or 4.3 billion times the 89.3 petawatts that hit the Earth. – David Hammen Mar 20 '19 at 10:07
  • @GrimmTheOpiner The same is true even of your stereo - that's why we have different measurements for different use cases. In the case of the laser, the peak power is important - it's about concentrating energy, not the amount of energy itself. In the case of your stereo, the mean power is important (if you want to play some loud music). The difference between the two can be rather large, especially when dealing with laser-based nuclear physics :) – Luaan Mar 20 '19 at 13:11
  • @RussellMcMahon very good point, i've updated the answer to include that important caveat – DenisS Mar 20 '19 at 13:22
  • @RussellMcMahon to be more specific: "the laser *emits* 10% of energy **reaching from Sun to Earth**". A laser does not produce energy. It takes it from some source and then emits it in a form of a beam. If we started producing energy at that scale you would get a thermonuclear reaction that would be far beyond control. Once initiated probably would continue until fuel lasts and **everything** would be fuel. On the other hand only a small fraction of energy *produced* by Sun reaches Earth and the laser was not even close to any meaningful percent of the energy produced by Sun at the same time. – Ister Mar 21 '19 at 15:26
  • @Ister My text is technically correct, aims at not being pedantic or overly complex for a layman. | My comment " .. While it is operating, the LASER IS generating 10% of the sun's energy". - Actually, ... , = "10% of the Sun's energy that falls on the outer atmosphere of the earth" - but, again, only during the time that the LASER is lasing ..." properly deals with the energy emitted. || A LASER (not laser) does "produce energy" just as much or as little as does a secondary or primary battery, a chemical reaction (such as "burning"), a star or anything else except creation "ex nihilo". Really. – Russell McMahon Mar 21 '19 at 23:32
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Power of the laser

This video shows interviews with people at the laser center. At 4:54 you can see the director of the center repeat the claim. In this video, that same director states that the laser was measured at 10.88 PW or 1.088×10^16 W. Remember that watts (W) are the unit of power.

The laser does not operate at that power continuously. Just for comparison, that power is 30 million times the generating power of the whole EU. The laser stores up power and releases it in very short bursts. This document was written during the design phase, and said that they would try to make the laser do pulses of 22 fs or 2.2×10^-14 s, which is an incredibly short time. I don't know how long the pulses are in the laser as built, but we can assume they are incredibly short.

Power of the sun

The claim is that the sun's power is only ten times that of the laser. The "power of the sun" is a little vague. There are different ways to think about the sun's power.

The sun sends 3.846×10^26 W into space in all directions. That is 10^10 or 10,000,000,000 times more than the laser. Most of this energy just flies off into space, and does nothing. A minuscule fraction of that incredible power hits the Earth. Roughly 1.73×10^17 W hits the upper atmosphere. Of the power hitting the upper atmosphere, only 71% is absorbed by the Earth, 1.2×10^17 W. This is just 11 times the power of the laser, which is consistent with the claim.

In contrast to the laser, the sun provides that power 24/7, and spreads the energy out over the whole Earth.

Some calculations for context

If we go back to basic physics, power is energy per unit time. A huge amount of power sustained for a very brief amount of time, is a moderate amount of energy. 10.88 PW sustained for 22 fs is 240 J, enough energy to power a CFL lightbulb for 16 seconds; Not much energy on a everyday scale. However, if even a small amount of energy is concentrated into a tiny enough space, it can produce very high concentrations of energy. The laser is remarkable not just for its incredible power, but also because it can concentrate that power into a microscopic space, briefly creating incredible concentrations of energy.

Conclusion The laser produces roughly 10% of the power of the sunlight that is absorbed by the Earth. It produces that much power for a tiny fraction of a second.

BobTheAverage
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    It produces that much ***power*** for a tiny fraction of a second. Mixing up energy and power is the crux of the matter. Power is energy (work) flow. It's like turning on a fire hose for a fraction of a second. – Schwern Mar 19 '19 at 19:47
  • @Schwern why would *anyone* claim it even ever generates 10% the amount of energy the sun generate(d)/will generate? Heck even in language I can't express that correct in present time and have to use future or past time (denoting different things), showing that intuitively it won't be conflated. But anyone can see that 4 billion years of "any" amount of energy equals more than a year of "some" amount of energy. (given human scales). – paul23 Mar 19 '19 at 21:14
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    @paul23 Because science reporting is often terrible and it sounds awesome and most laymen have no sense of scale (I cite any given disaster movie as evidence) and we confuse energy with power all the time. – Schwern Mar 19 '19 at 22:32
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    "It produces that much energy for a tiny fraction of a second" - In addition to what @Schwern said, it would be more clear to say "It **outputs** that much ...". The laser isn't producing power, it's (very rapidly) releasing energy that was produced elsewhere and then stored. – aroth Mar 19 '19 at 23:32
  • @Schwern The statement re energy is "correct enough" but confusing. The claim can be made understandable by adding the implied " ... while it is lasing ... ". ie Power = energy per time. Energy =Power x time. Time involved must be cited when converting between the two. I know you know that. – Russell McMahon Mar 20 '19 at 02:59
  • @aroth That energy wasn't "produced elsewhere", it came from elsewhere. Producing energy is simply impossible. – Dmitry Grigoryev Mar 20 '19 at 15:33
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    @DmitryGrigoryev "Converted from one form of energy into another more usable form," then? – JAB Mar 20 '19 at 18:03
  • @DmitryGrigoryev - Technically I suppose it was "produced" in the sun, via fusion. Or I guess you mean even more technically that matter and energy are the same thing and exist in a fixed quantity. But in common parlance I think it's understood that converting one form of energy (kinetic/solar/chemical/etc.) into a more usable form of energy (electrical) is "energy production", conservation of energy/mass notwithstanding. A generator "produces" power, a laser consumes, stores, and releases/outputs power. It's not strictly scientifically accurate, but colloquial English rarely is. – aroth Mar 21 '19 at 07:03
  • @aroth What's your argument about the laser then? It consumed some electrical energy, and then produced a short pulse of light, just like a generator consumed some chemical/mechanical/nuclear energy to produce electricity. – Dmitry Grigoryev Mar 21 '19 at 07:48
  • @DmitryGrigoryev - The laser output light and heat, both of which are less directly usable than the electrical energy is used to do that. Therefore it's doing effectively the opposite job of a generator. – aroth Mar 21 '19 at 10:08
  • @aroth I have no idea what a "less usable" energy is, could you clarify that? Also, all generators produce waste heat too. – Dmitry Grigoryev Mar 21 '19 at 12:23
  • Less _directly_ usable, by humans. For and by the things that humans typically use energy for. So mostly, anything that's not electrical energy is "less usable". You can't, for instance, run your TV off the laser. At least, not without pointing it at some tritium, extracting some heat from the fusion reaction that occurs, and then using that heat to spin a generator. – aroth Mar 21 '19 at 12:38
  • @aroth Using a similar example, heat is indeed directly usable: you can't cook with electricity without first converting it to heat. You need the right kind of energy for the right purpose, so if you need a coherent radiation pulse, you produce it with a laser. – Dmitry Grigoryev Mar 21 '19 at 12:47
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    This conversation about semantics has gotten a little out of hand. Is it really useful to talk this much about what the word produce means? – BobTheAverage Mar 21 '19 at 15:22