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Which invention involving light has changed the world the most?

cstanton — Mon, 09 Nov 2026 10:35:43 GMT

Diwali, the Festival of Lights, is celebrated by millions of people around the world, making this a fitting month to turn our attention to the engineering and technology of light.

From illuminating our homes to carrying information across continents, generating electricity and allowing us to see the otherwise invisible, engineers have found some extraordinary uses for light.

So, for this month's Question of the Month, we want to know: which invention involving light has changed the world the most?

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There's plenty of room for debate here. The LED transformed lighting and displays, lasers underpin technologies ranging from manufacturing to communications, fibre optics carry enormous amounts of the world's data, while solar cells turn light itself into useful electrical energy.

And perhaps we've missed the invention you'd put above all of them.

Tell us what you picked and why in the comments. We're particularly interested in hearing from engineers who've worked with these technologies firsthand.

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RE: Which invention involving light has changed the world the most?

beacon_dave — Fri, 13 Nov 2026 18:59:49 GMT

Perhaps depends on if you were 'blinded by the light'...

RE: Which invention involving light has changed the world the most?

dougw — Thu, 12 Nov 2026 19:21:22 GMT

Or "it looks pretty awesome" 🙂

RE: Which invention involving light has changed the world the most?

geralds — Thu, 12 Nov 2026 10:02:36 GMT

I still remember it a little...
When I was about 19, I wanted to build a laser using a ruby crystal.
I ordered one—65 mm long and 5 mm in diameter—and had a specialist (a company that manufactures mirrors and custom optical components) grind the "Brewster" angle onto it.
https://en.wikipedia.org/wiki/Ruby_laser

https://en.wikipedia.org/wiki/Brewster%27s_angle

Then I would have liked to buy the two deflecting mirrors and the pump lamp, as well as the electronics, but unfortunately, as an apprentice at the time, money was tight, and so I was unable to complete this project.

Yes, light and optics are fascinating.
-

Here an actual book at Elektor, LEDS, Laser, Sunlight:
https://www.elektor.de/products/leds-lasers-and-sunlight-e-book

This book is very useful, it tells in easy to be understanding words the basics about LEDs, laser and the sunlight.

To all the specialists, hobbyists, tinkerers, and everyone who enjoys exploring the physics of the cosmos:
I wish you all the very best and much success with your wonderful projects.

The cosmos provides us with so many ideas and inventions that we can put to good use.
My thanks go to the great Creator, who fashioned everything so magnificently.
Let us do this with respect and reverence, helping one another, so that everyone—yes, truly everyone—may derive great benefit.

RE: Which invention involving light has changed the world the most?

gpolder — Wed, 11 Nov 2026 07:35:06 GMT

RE: Which invention involving light has changed the world the most?

shabaz — Wed, 11 Nov 2026 02:43:38 GMT

One reason why I worked as a fresh grad at Nortel Networks for a very short while.. one of their sites near me was where they had done work on fiber optics (an acquisition of a UK firm) and I hoped to learn a bit, but I landed up messing with Excel spreadsheets for six months, so I left, although I really liked the team.

There were a ridiculous amount of scandals just prior to their demise.. there was a airplane event that was like the Astronomer CEO thing tenfold, there was a murder at one point that got Netflixed, plus the financial irregularities. A pity.. wish it had been just a normal company..

RE: Which invention involving light has changed the world the most?

kmikemoo — Wed, 11 Nov 2026 02:19:39 GMT

spinden That was how I made my choice. What technology do we take the most for granted?

RE: Which invention involving light has changed the world the most?

davebullockmbe — Tue, 10 Nov 2026 16:10:57 GMT

The optical microphone, as it allowed me to design and develop audiophile quality sound presentation headphones, with an additional 40dB of noise cancellation for fMRI auditory cortex mapping and subsequent (in scanner) surgical interventions.

RE: Which invention involving light has changed the world the most?

javagoza — Tue, 10 Nov 2026 16:02:17 GMT

The refrigerator light. Is yours off right now?

RE: Which invention involving light has changed the world the most?

scottiebabe — Tue, 10 Nov 2026 15:40:47 GMT

the internet

RE: Which invention involving light has changed the world the most?

geralds — Tue, 10 Nov 2026 11:32:37 GMT

In my opinion, fire— fireplace —was the first thing that changed the world.
Two flints struck together—and the "stars" were born.

The sun inspired humans to create magnificent inventions using light.
Place a prism in the sunlight, and you will experience something fantastic.
Who was the inventor of the sun? 😎 We know that.

When I was 16, I had the idea of building a laser microscope—inspired by a book that featured an electron microscope (published in 1975).
A book from 1975, in a section on "optical instruments," described how to manufacture a parabolic mirror (for a reflecting telescope).
I build then a microscope as well a telescope.
How can you check the cleanliness of a mirror's surface? By using reflection.
Simply shine a point of light onto the mirror and adjust its angle so that the surface is projected onto a wall, appearing greatly magnified.
Suddenly, you can see the tiniest dust particles, glass fragments, or even the smallest scratches and indentations.
That was the spark for me back then: not to build an electron microscope, but a laser microscope.
Well, what can I say? In the year 2000, I saw exactly such a laser microscope in a laboratory at Siemens.

LCD flat-screen displays:
That was a similar phenomenon for me.
Around the same time, I owned a pocket calculator with an LCD display.
The idea? An X-Y matrix filled with transistors controls the individual pixels of the LCD—and this assembly has to be thin enough
that the entire screen can be hung on a wall. Well, what can I say? That is exactly how it’s done today.
That became my selling point for working at a television manufacturing company; I went on to work for Philips and Grundig.

LEDs, lasers, and masers have always been central to both my professional career and my personal hobbies.
You can never have too many LEDs; they are always being integrated into something.
The problem lies in the materials used and, in many cases, the greed for wealth and power (personal, political, religious, or whatever).

We humans love light; we all need light.
Otherwise, we become afraid, because we cannot see our own feet to take a step forward.

RE: Which invention involving light has changed the world the most?

OwainM — Tue, 10 Nov 2026 10:21:35 GMT

I may be being contrary, but there's so much more to light than just the visible!

The non-visible parts of the electromagnetic spectrum, I'm choosing radio in this case, have allowed so much technology to be possible.

There's not a single day where I don't make use of something using some form of radio.

RE: Which invention involving light has changed the world the most?

veluv01 — Tue, 10 Nov 2026 06:16:36 GMT

[quote userid="18385" url="~/members-area/f/forum/57431/which-invention-involving-light-has-changed-the-world-the-most/238976"]...$149?[/quote]

It's open source and btw it's from the Arduboy's creator, he's just getting on the R&D costs from the limited edition stocks.

RE: Which invention involving light has changed the world the most?

gordonmx — Tue, 10 Nov 2026 05:48:21 GMT

God said "Let there be Light" sounds pretty awesome!

RE: Which invention involving light has changed the world the most?

dougw — Tue, 10 Nov 2026 05:22:54 GMT

All spectacularly important technologies. There are likely way more LEDs in use than all the other technologies combined. Of course I'm also partial to LEDs since I have a patent in the high brightness LED traffic lights field. Actually I have a patent in the fiber optics field as well, but the resulting products are not visible to consumers.

RE: Which invention involving light has changed the world the most?

spinden — Tue, 10 Nov 2026 02:08:44 GMT

What a great question! I had to think about it for a minute. We take for granted so much of these technologies, yet, without them, our modern society would be very different.

RE: Happy Diwali everyone.

cstanton — Mon, 09 Nov 2026 13:19:30 GMT

I may have had tool assistance 😃

Happy Diwali everyone.

embeddedguy — Sun, 08 Nov 2026 12:48:26 GMT

Happy Diwali to everyone.!

Diwali is a festival of light. One of the most important festivals in India

Time for me to do some crackers. [emoticon:0f36700dfeb3494fa10d47dd9e1f90a1]

Interestingly, found this cool wish from Element14 on Instagram.

Credits: element14 Company Instagram

RE: Which invention involving light has changed the world the most?

cstanton — Mon, 09 Nov 2026 13:18:25 GMT

...$149?

It could have been... an LED 'cube' matrix at the top, or a holographic display, or a persistence of vision display.

At least it's USB-C

RE: Which invention involving light has changed the world the most?

michaelkellett — Mon, 09 Nov 2026 11:16:44 GMT

The standout invention relating to light is more of a discovery than an invention but .....

Einstein didn't get his Nobel prize for Theory of Relativity but his work on photoelectric effects.

Without this earlier success I doubt that we would ever have heard of him.

There is a good simple language explanation here:

https://timesofindia.indiatimes.com/science/how-your-smartphone-camera-exists-because-of-albert-einstein-the-nobel-winning-idea-that-was-once-considered-bizarre/articleshow/131171387.cms

Times of India isn't my usual every day reading (found the article looking for corroboration of my recollections re Einstein) - but maybe it should be !

RE: Which invention involving light has changed the world the most?

veluv01 — Mon, 09 Nov 2026 11:00:48 GMT

I would choose the Digital Candle ! It might not be the most important invention, but quite niche for festival of lights. Well, AI is everywhere now!

RE: Which invention involving light has changed the world the most?

embeddedguy — Mon, 09 Nov 2026 10:43:20 GMT

I have worked with many inventions involving light, but I think that camera sensors are most game changing and innovative. Cause it helped us store a moment in time on a piece of paper.!

RE: Happy Diwali everyone.

embeddedguy — Mon, 09 Nov 2026 09:33:50 GMT

धन्यवाद | लगता है आपने AI का इस्तेमाल किया है। 😀

RE: Happy Diwali everyone.

cstanton — Mon, 09 Nov 2026 09:22:35 GMT

दीपावली की हार्दिक शुभकामनाएँ!

RE: Happy Diwali everyone.

Shishir — Mon, 09 Nov 2026 04:00:25 GMT

Happy Diwali Everyone!