# Oldest Interstellar Radio Broadcast **URL:** \ **Category:** Factual Questions\ **Created:** [December 8, 2003, 7:15am UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716 "2003-12-08T07:15:03Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![myles](https://avatars.discourse-cdn.com/v4/letter/m/779978/32.png) [@myles](https://boards.straightdope.com/u/myles)\ **Post date:** [December 8, 2003, 7:15am UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/1 "2003-12-08T07:15:03Z")
Say that there are intelligent people on a planet orbiting Alpha Centauri, not only that, say that they have a S.E.T.I. program virtually identical to ours listening to the stars for radio broadcasts. What was the oldest broadcast from Earth, whose broadcast was strong enough, that would could be taken as signs of intelligence by the Alpha Centaurians? In other words, were the first radio broadcasts strong enough that they wouldn’t dissipate and die out after 4 light years of travelling through space? ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 8, 2003, 6:10pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/2 "2003-12-08T18:10:08Z")
Doesn’t the answer to this question depend entirely on the sensitivity of the receiver? ---
**Author:** ![myles](https://avatars.discourse-cdn.com/v4/letter/m/779978/32.png) [@myles](https://boards.straightdope.com/u/myles)\ **Post date:** [December 8, 2003, 6:26pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/3 "2003-12-08T18:26:14Z")
> [@](#): > > \*Originally posted by Exapno Mapcase \* > \*\*Doesn’t the answer to this question depend entirely on the sensitivity of the receiver? \*\* Look at the question again, “say that they have a S.E.T.I. program virtually identical to ours” So, if they have an equal sensitivity to our S.E.T.I. program, what will be the first message that they will be able to interpret as signs of intelligence? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [December 8, 2003, 7:20pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/4 "2003-12-08T19:20:27Z")
Some of the earliest commercial radio and television broadcasts in the late 20’s and early 30’s would have been easily strong enough to be detectable by an Arecibo-type radio telescope from 4.3 LY. ---
**Author:** ![netscape\_6](https://avatars.discourse-cdn.com/v4/letter/n/8c91f0/32.png) [@netscape\_6](https://boards.straightdope.com/u/netscape_6)\ **Post date:** [December 8, 2003, 7:29pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/5 "2003-12-08T19:29:25Z")
something to think about for this question is nasa used transmiting equipment on the viking landers no more powerfull then a walkie talkie. it was actually cheaper to build powerfully senstive equipment on earth then to spend the money on rocket power to send more powerfull transmitters. however nasa knew what signal to look for on what frequency. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [December 8, 2003, 8:34pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/6 "2003-12-08T20:34:28Z")
Debating whether or not the Centaurans are watching Hitler footage from the 1936 Olympics? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 8, 2003, 8:58pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/7 "2003-12-08T20:58:46Z")
My hazy memory of the numbers is at odds with what **Q.E.D.** says there… I seem to recall hearing that no human transmission to date could be detected with current human technology four lightyears away. I’ll see if I can find numbers. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 8, 2003, 9:01pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/8 "2003-12-08T21:01:13Z")
Sorry, I meant that our SETI program is not a single thing, it’s a bunch of different receivers scanning different bands at different sensitivities, and a whole bunch more variables. I just think you needed to provide more information to properly answer this. I’d like more information on **QED’s** claim as well. What wattage are you assuming for these radio broadcasts? 50,000 watt clear channel stations did exist by the 1930s (I’d have to check on the 1920s). A few 500,000 watt experimental stations were created - I believe there was one in Cincinnati, and Mexico had fewer restrictions on power than the US - but I’m not sure that the timing for these is right. I realize that our spacecraft use extremely low wattage signals, but the signals are directed and their positions are known, and even so we lose the signal a good ways short of Alpha Centauri. I’d also dispute that commercial television broadcasts from the 1920s or 30s would be receivable. All the attempts I’m familiar with were fairly low power. Also remember that most tv at the time used scanning disk technology that would be difficult if not impossible to reproduce without knowledge of the source. Electronic scanning did exist, but was barely viable until the late 1930s. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [December 8, 2003, 9:32pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/9 "2003-12-08T21:32:24Z")
> [@](#): > > **We can detect the levels of our own radio/TV at 5 light years**. There is only 1 star system (alpha Centauri) within 5 light years of Earth. This is isotropic radiation, which goes out in all directions. > > We can detect the power transmitted by our military radar at 40-50 light years. There are over 1000 stars within this volume. > We can detect directed gigawatt (GW) power beamed at us from across Galaxy. We can and have transmitted signals of this power from the Areciebo radio telescope, the world’s largest radio telescope (see image to left). Using Arecibo, we could detect a full power signal sent by an identical telescope across the Galaxy, 100,000 light years distant. From [here.](http://www.ess.sunysb.edu/fwalter/AST248/seti.html) Bolding mine. ---
**Author:** ![A\_Curious\_Writer](https://avatars.discourse-cdn.com/v4/letter/a/ed8c4c/32.png) [@A\_Curious\_Writer](https://boards.straightdope.com/u/A_Curious_Writer)\ **Post date:** [December 8, 2003, 10:20pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/10 "2003-12-08T22:20:34Z")
thanks, QED. I read that topic, and the first thing that I thought of was, why was Mork only referencing very recent stuff. I mean, even if the sitcom assumed an audience unfamiliar with a lot of old-time stuff, you’d think Robin Williams’ character would have thrown in more references to past Earth stuff they’d received on Ork, more than I recall him doing anyway. Then again, maybe they were more accurate than I thought - perhaps their SETI system could only receive certain stuff. It would dissipate after a while, after all. (Dollars to donuts a similar thread gets starts in Cafe Society now 🙂 ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 8, 2003, 10:25pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/11 "2003-12-08T22:25:02Z")
That site doesn’t really answer the OP’s question, though. That we send out a major signal today doesn’t say anything about when that signal became major. The “levels of our own radio/TV” are given here: > [@](#): > > FM radio and TV are not blocked by atmosphere. Our presence is being announced to the stars by our television. The Beverly Hillbillies are among our interstellar emissaries. > > Today we transmit about 100,000 MW in FM/TV; much of this escapes to space. We certainly didn’t transmit anything like that in the 1920s or 30s. FM and TV signals were essentially negligible until after WWII. Although they mention Marconi, they don’t get into the issue of how much of AM leaks through the atmosphere. Nor do they talk about short-wave transmissions, which were a major part of radio from an early date. I consider this question still completely open. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [December 9, 2003, 12:29am UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/12 "2003-12-09T00:29:55Z")
> [@](#): > > \*Originally posted by Exapno Mapcase \* > \*\*We certainly didn’t transmit anything like that in the 1920s or 30s. FM and TV signals were essentially negligible until after WWII. \*\* Oh? I wouldn’t call [500,000 watts](http://www.enquirer.com/editions/2001/09/12/tem_cds_capture_glory.html) “negligible”. > [@](#): > > Broadcasting on 500,000 watts, 10 times today’s power, WLW-AM was the most powerful U.S. radio station from 1934 to 1939. That’s why they called it “The Nation’s Station.” ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 9, 2003, 1:30am UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/13 "2003-12-09T01:30:29Z")
Didn’t the **AM** in WLW-AM ring a warning bell? I said **FM and TV** signals were negligable. And in previous posts I already noted that Cincinnati had a 500,000 watt AM station, but wondered how leaky AM signals were because if the signals didn’t penetrate the atmosphere they wouldn’t be much good on the next star. Still don’t know the answer to that. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [December 9, 2003, 1:40am UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/14 "2003-12-09T01:40:44Z")
Depends largely on atmospheric conditions. There are conditions under which the atmosphere becomes largely transparent to longwave EM. Of course, I don’t know, and probably can’t prove one way or the other, if such conditions ever occurred at during the time the station was operational. Yes, I’ll grant the question is still open, but I believe we’re getting closer to a concrete answer. Anyone want to take a quick trip to Alpha Centauri? ---
**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\ **Post date:** [December 9, 2003, 1:19pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/15 "2003-12-09T13:19:54Z")
Turning the question around (having not yet ploughed through the SETI site), are we therefore certain that:[ul][_]nobody within 5 LY is broadcasting TV (or indeed anything more advanced/efficient)[_]nobody within 40-50 LY is broadcasting military radar or better nobody in the galaxy has swept the heavens with a Gigawatt beam continuously for the last 100,000 years?[/ul]How depressing. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [December 9, 2003, 1:43pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/16 "2003-12-09T13:43:54Z")
That’s cause we’re still the only savages left in the universe still using _radio_, for heaven’s sake. I mean come on, it’s just a step up from beating on freaking drums! 😃 ---
**Author:** ![dropzone](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dropzone/32/7515_2.png) [@dropzone](https://boards.straightdope.com/u/dropzone)\ **Post date:** [December 9, 2003, 1:44pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/17 "2003-12-09T13:44:29Z")
> [@](#): > > \*Originally posted by Bryan Ekers \* > \*\*Debating whether or not the Centaurans are watching Hitler footage from the 1936 Olympics? \*\* Jeeze, sounds like the History Channel Live! ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [December 9, 2003, 1:54pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/18 "2003-12-09T13:54:32Z")
Carl Sagan had the aliens seeing first Hitler broadcasts (in his book **Contact** ), but he missed a much better “first” Long before Hitler’s broadcasts, Hugo Gernsback (seminal publisher of science fiction, after whom the “Hugo” awards are named) used to broadcast TV signals out of New York. Back in the 1920s. Don’t know if any of them were powerful enough to survive noise-free enough to be received by aliens. ---
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [December 10, 2003, 2:18pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/19 "2003-12-10T14:18:45Z")
Nikola Tesla made several extremely high-power CW, AM broadcasts into space. These started in the 1890’s…and I don’t know how they were modulated. I have read that Tesla tried to signal Admiral Peary’s 1909 North Polar expedition-again I don’t know the details. So perhaps, the bug-eyed monsters are this very minute, puzzle dby the rantings of a long-dead serbian genius! ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 10, 2003, 6:51pm UTC](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716/20 "2003-12-10T18:51:07Z")
In the 1890s? Probably not. [http://www.radioelectronicschool.com/downloads/whoinventedradio.pdf](http://www.radioelectronicschool.com/downloads/whoinventedradio.pdf) > [@](#): > > Tesla spent the last remains of his money on building a series of radio transmitters and receivers. In 1895 he was ready for a demonstration, which would involve communication with a ship he would hire to sail the Hudson river. Then calamity overtook him: his laboratory was completely gutted by fire the night before the final tests. Equipments, records, tools, all were lost. Typically Tesla had not bothered with insurance, and as his money was gone, Tesla was ruined. Tesla did some very-low-frequency experiments in the early 20th century that traveled long distances, but I don’t know how well these would be propagated outside the atmosphere. He also claimed to _receive_ interstellar signals in 1899, presumably the same type of noise that would plague later radio astronomers. Nobody believed him then, and it’s hard now to know what if anything he heard. Somebody may be conflating this with _sending_ signals, I suppose. You have to be very careful with claims about Tesla. All too many of them are in the same league with his building a death ray that caused the Tunguska explosion. [Next page](https://boards.straightdope.com/t/oldest-interstellar-radio-broadcast/217716.md?page=2)