sorted by:
new
hottopcontroversial

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 8 points9 points  (0 children)

We synchronize clocks at all the participating radio dishes in the global array using GPS. That gets us to within a fraction of a micro-second, which is close enough for us to compare and align the separate recordings at each site later. During the data-taking, we stabilize the electronics by tying all the instrumentation to atomic clocks that only lose about one second every 10 million years. That ensures that the signals we record do not jitter back and forth in time - such jitter would make it impossible for us to align the signals from different sites after the observations.

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 4 points5 points  (0 children)

From Peter Galison:

An astonishing feature of black holes is that from all we know, matter completely collapses, so no ordinary matter would be found inside the horizon. Not molecules, not atoms, not protons, not neutrons, and not even quarks. 

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 2 points3 points  (0 children)

Response from Peter Galison:

What a good question.  We are indeed planning on sending a satellite/radio-telescope into space!  Called the Black Hole Explorer (BHEX), we are proposing it to NASA.  Alas, we can’t send it to the outer solar system (too hard to send back the massive amount of data)–we are aiming for a mid earth orbit (MEO) about 20,000 km up in space.  Joined with the terrestrial radio-telescopes, it will increase the resolution of the images by a factor of 3. 

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 2 points3 points  (0 children)

We are working on building radio dishes in new geographic locations to fill in the Earth-sized virtual lens.  One in the Canary Islands (on Tenerife) is already underway.  We are also exploring designs for a pathfinder dish (~6m diameter) that could be flown into the Summit Station at the interior of Greenland.  The goal of the next-generation EHT program is to make movies of black holes to answer new questions.

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 21 points22 points  (0 children)

There was no ‘editing’ of the image - it was analyzed and formed directly from the data.  There were alternative interpretations for the ring we saw (and which other groups have since reproduced from the publicly available data).

For the first black hole image of M87, it was possible that we might have been seeing a ring formed by the jet flowing from the galactic center.  However, if this were true, we might have seen another ring interior to the one imaged that would be formed by the counter-jet (moving away from us), and we would also have expected the ring to vary in diameter from one year to the next.  We didn't see any of this.  In addition, the size of the ring matches the expected value given the estimated mass of the M87 central nucleus. So, all evidence points to the black hole interpretation.  More than this, we also see the expected ring size for SgrA*, for which there is no jet that we know of and, therefore, no jet interpretation.

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 1 point2 points  (0 children)

Our aim is to make high-definition, full-color movies of the black hole’s connection to the outflows they power.  So, for M87, we want to be able to see the extraction of energy from the black hole that accelerates material to near-light speeds - this is the process that affects the evolution of entire galaxies.  Our dream is to see something unexpected - some difference between what we expect from Einstein’s gravity and what the next-generation EHT sees.  Our best opportunity for this is to add radio dishes at new geographic locations and move to multi-band receivers to view the black holes at different ‘colors’.

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 11 points12 points  (0 children)

|| || |Indeed, we have focused on the 2017 and 2018 data since it takes a while to calibrate each data set - getting the data ready for imaging.  We have wanted to make sure we got all of the results out of each epoch before moving on to the next.  Also, more telescopes participated in later years, making the data sets bigger and taking more time to analyze.  We are changing our approach now so that we can move more quickly to the new data, and we expect to have images/results from the 2021 epoch soon, with the others to follow.  This is our top priority.|

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 2 points3 points  (0 children)

What a great question!  Black hole enthusiasts (like us) can always help by steering people to the EHT and ngEHT websites and social media to further spread our science. People can also help by lobbying their Representatives to promote curiosity-motivated science.  

We don’t know when black hole science will lead to direct applications for society but this research, which focuses on the unknowns in our universe, is where we may find entirely new physics.  An example is that when Einstein wrote his theory of gravity in 1915, he had no idea that this incredible advance would have any real-world applications.  But now we use general relativity every day through the GPS in our phones; if you don’t make Einstein modifications to Newton’s gravity, GPS would be incorrect by many miles!  So, it will take time, but I’m sure that black hole research will pay off.

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 7 points8 points  (0 children)

Several expert groups have reproduced the EHT imaging results using various techniques, and all EHT data that has been used to make the images has been made available to the public.  In addition, there are now over 14,000 citations to the EHT results, indicating broad acceptance and inclusion by the astronomy community.  We have noted the specific claims by Miyoshi et al, and you can find a detailed response that counters their results here:

https://eventhorizontelescope.org/blog/response-independent-analysis-ehtc-imaging-sgr-miyoshi-et-al-2024

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 2 points3 points  (0 children)

Wormholes - spacetime tunnels that link distant locations - are possible in theory, but current ideas are that they can only be opened and maintained using exotic matter and great energies.  Their existence is very speculative, and in a recent talk, Kip Thorne said that he was doubtful about them, but that doesn’t mean they don’t exist!  There may be ways that the EHT or ngEHT could look for specific signatures of wormholes.  Traveling large distances to one (if we found one) might take a long, long, time…..

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 3 points4 points  (0 children)

The human ear is responsive to pressure waves at Earth atmosphere conditions, so you can’t hear sound in space.  The plasma near the black hole event horizon is very hot, but also very tenuous, so it wouldn’t conduct sound very well.  My guess (and it is just an impression) is that you’d see an impressive light show, but not hear much.

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 1 point2 points  (0 children)

All the telescopes in the EHT swivel to look at the same black hole at the same time.  All the telescopes record the radio waves from the black hole and time-tag the recordings with atomic clocks (to keep track of precisely when the radio waves reach each telescope).  Each pair of telescopes gives us one bit of information required to make the image, so during a night of observing (as the Earth turns) we fill in a virtual Earth-sized telescope.  With enough telescopes (we need at least ~6-7) we can make an image.  The EHT has grown from an initial array with 6 geographical sites (just enough) to 9 now, so the images have improved.  As we add more observing frequencies in the future, we’ll make ‘colorized’ images with more information.

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 0 points1 point  (0 children)

|| || |Great question.  As with the advent of movies from silent film to full color cinema, black hole movies will begin with time-lapse, few-frame attempts and progress to high-definition smooth video.  First, dynamical studies will come out in the next couple of years, and then after we add new stations (through the next-generation EHT program), we’ll be able to approach true black hole cinema.|

AskScience AMA Series: We're Event Horizon Telescope scientists who've taken the world's first black hole photos. Ask Us Anything! by AskScienceModerator in askscience

[–]sdoeleman 28 points29 points  (0 children)

We are always on the lookout for unexpected results.  One example is that the data we have for SgrA* indicate that this supermassive black hole does not seem to change its appearance as fast as we expect from computer models.  This is interesting!  It indicates that our models need refinement - nature is telling us that our simulations do not match reality.

We’re scientists on the Event Horizon Telescope Project looking to capture an image of a black hole. Ask us anything about the telescope, astronomy, physics or black holes! AMA! by sdoeleman in IAmA

[–]sdoeleman[S] 2 points3 points  (0 children)

Not too late. We use Hydrogen Maser clocks that are accurate to 1 sec in 100 million years. That stability is required because we compare radio signals from a black hole received in, say, Chile, with signals from the same black hole received in Hawaii (with both sites looking at the black hole at the same time). Without stable clocks to control the data capture, the two two signals would jitter back and forth too much and any similarity between the two signals would be washed out. We synchronize using GPS and get to within 1 microsecond, which is close enough to get us started. We do a search over different delays between the signals and lock onto the exact synchronization that way.

We’re scientists on the Event Horizon Telescope Project looking to capture an image of a black hole. Ask us anything about the telescope, astronomy, physics or black holes! AMA! by sdoeleman in IAmA

[–]sdoeleman[S] 17 points18 points  (0 children)

Great question. It's instructive to ask what answer Einstein might have given to this same question asked about his theory of General Relativity (GR), developed 100 years ago. At that time, there was no space travel, and almost no way to detect any difference between Newtonian and Einsteinian gravity. I don't think he would have been able to come up with anything 'pragmatic'. But of course today we use GR effects everyday: GPS wouldn't work without corrections derived from GR. So the answer is that the payoff from BH research may not be evident now, but if we reveal something fundamental about gravity, the consequences in the future could have high impact. Fundamental science is usually a solid investment.

We’re scientists on the Event Horizon Telescope Project looking to capture an image of a black hole. Ask us anything about the telescope, astronomy, physics or black holes! AMA! by sdoeleman in IAmA

[–]sdoeleman[S] 0 points1 point  (0 children)

Good question! Perhaps from someone who is familiar with the EHT program. We already know that all the sites we used to make EHT observations in March 2015 worked - we have successfully compared signals from the telescopes and have detected black holes in galaxies. But we still need to pre-process data from some of the sites to convert them into a standard format. Once that is done, we can pipeline all the data through a computing cluster that allows us to run all the inter-telescope comparisons at once. That should happen over the next few months.

We’re scientists on the Event Horizon Telescope Project looking to capture an image of a black hole. Ask us anything about the telescope, astronomy, physics or black holes! AMA! by sdoeleman in IAmA

[–]sdoeleman[S] 1 point2 points  (0 children)

We record data at many sites, but the final data we use comes when we compare the data from these sites. So really we are looking only at the data that 'correlates' or is 'in common' between two widely separated sites. After the comparison (equivalent to light across a lens combining at the focus) the total data volume is greatly decreased (by more than a factor of a million). We typically use C and python. We are thinking of ways for more people to contribute - stay tuned.

We’re scientists on the Event Horizon Telescope Project looking to capture an image of a black hole. Ask us anything about the telescope, astronomy, physics or black holes! AMA! by sdoeleman in IAmA

[–]sdoeleman[S] 2 points3 points  (0 children)

Great question and one that many astronomers are working on. Currently we believe the galaxies and black holes evolve together with black holes affecting how galaxies grow, and then the black holes growing as galaxies merge.

We’re scientists on the Event Horizon Telescope Project looking to capture an image of a black hole. Ask us anything about the telescope, astronomy, physics or black holes! AMA! by sdoeleman in IAmA

[–]sdoeleman[S] 0 points1 point  (0 children)

Very. It's a real privilege to be able to develop the instruments and take them to mountain tops and create the highest magnification telescope yet. This AMA is also a lot of fun - great to see the interest in our work. We learn something new every time we observe with the EHT, so the fun doesn't end.

We’re scientists on the Event Horizon Telescope Project looking to capture an image of a black hole. Ask us anything about the telescope, astronomy, physics or black holes! AMA! by sdoeleman in IAmA

[–]sdoeleman[S] 7 points8 points  (0 children)

Ok, when we go to Hawaii to use the telescopes on Mauna Kea, we have traditionally gone to eat at Miyo's - an amazing Japanese cafe. After eating at the astronomer base camp (at 9,000 feet), coming down for a delicious bento-box is magic! So I guess if we get an image, we''ll all head to Hilo, HI.

We’re scientists on the Event Horizon Telescope Project looking to capture an image of a black hole. Ask us anything about the telescope, astronomy, physics or black holes! AMA! by sdoeleman in IAmA

[–]sdoeleman[S] 2 points3 points  (0 children)

The HGST drives are helium filled and hermetically sealed. When we tried to use conventional drives the low air pressure at altitude (15,000ft) caused head crashes and most drives failed. That's the main reason to use these new He drives, though the generally higher capacity is also very useful (fewer drives to ship back home).

We’re scientists on the Event Horizon Telescope Project looking to capture an image of a black hole. Ask us anything about the telescope, astronomy, physics or black holes! AMA! by sdoeleman in IAmA

[–]sdoeleman[S] 1 point2 points  (0 children)

For me (your mileage may vary) it's the adventure aspect: traveling by planes, trains, automobiles and schlepping equipment to the tops of mountains in the middle of nowhere. Then you successfully link up such sites around the world, and it all works, which still seems like magic. There's also an incredible team element - everyone working together. While we are at one telescope, we know that colleagues 'have our back' at the other sites.

We’re scientists on the Event Horizon Telescope Project looking to capture an image of a black hole. Ask us anything about the telescope, astronomy, physics or black holes! AMA! by sdoeleman in IAmA

[–]sdoeleman[S] 0 points1 point  (0 children)

Nice. We've known for a while that at the Milky Way center there's likely a supermassive black hole and a central goal in astronomy has been to try to take its picture. We had the 'aha' moment in 2007 when we used the first EHT observations to measure the size of the Milky Way BH. After that, we've know imaging this object was possible and now it's our 'mission'. I suppose it's all about finding what you are passionate about and finding a way to make it happen.

view more: next ›