12 Billion-year-old signal from the end of the universe's 'dark age'

"Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway" - A. Tanenbaum of MINIX (amongst other things) fame

I recently found out that that is referred to as the sneakernet, and is actually still a preferred way to transfer a lot of data. https://en.wikipedia.org/wiki/Sneakernet

I worked for a company CERN had bought equipment from a while back. I was on the technical support team. I had a direct path to engineering when CERN called. The amount of data in an ultra short time was seemingly endless.

So many "need more interfaces, more bandwidth...buffer tuning... buffer tuning".

When a card burnt up mysteriously I made a sci fi joke about black holes and CERN in my ticket to engineering. It was the one and only time I got them to make a joke back ;)

The MWA has a direct fibre connection from site to a super computing facility in Perth. Although some processing (correlation and averaging) is usually done on site to reduce the data a little, there are some observation modes that send the raw voltages.

This is how Google Street view cars work too, because the sheer size of the high resolution photograpic data is so huge that it would make no sense to transmit it over a mobile network, vs just downloading it once the car finishes it's route.

I was just leaving radio astronomy when the MWA was in later stages of design/deployment, I remember the discussions around designing the data storage for it, and it was centered around the idea of having to fly the data set back and forth (At the time, around 2008-2011ish?) - so it was so large that it wasn't really feasible to use the Internet for each data collection run. On the order of many terabytes if I recall correctly.

That isn't as uncommon as you may think. Especially when talking about DR (disaster recovery) plans, sneakernet is certainly a valid way to get backup data from off-site because you never know what the network status will be when you need to enact your plan.

Event horizon telescope used HDD's being flown around to aggregate their data

> Now, my question is, how is it possible that we can see so far in the past?

I think you're overthinking it. Forget about expansion for a moment, or other weird effects. We can see 12 billion years into the past because the universe is far larger than 12 billion (or 24 billion) light years across--possibly infinite, possibly not, but nonetheless at least that large, and at least that large at the moment the signal was emitted. What we're seeing isn't a reflection, it's light that has been traveling 12 billion years in a straight line from point of origin.

Because of expansion, the earth[1] and the emission source may have been closer than 12 billion light years, but they were still very far apart. The big bang doesn't mean the universe exploded from a point source, at least not in any intuitive sense of the phrase. The exact topology is still unknown, but assuming a flat, infinite universe, the universe was already flat and infinite when the signal was emitted.

See https://en.wikipedia.org/wiki/Shape_of_the_universe

[1] Disregarding that the earth and our solar system didn't yet exist.

The universe is bigger than the observable universe.

I found a good article on this matter: https://arxiv.org/pdf/astro-ph/0310808v2.pdf

My guess is that these signals are ambient in nature, like microwave background radiation. Like the article mentions, it is assumed that they changed the wavelength over time but in theory they exists.

Imagine it is something like ambient light of a room without a light source during the day

The emission is the so-called ‘forbidden’ hyperfine transition of the spin state of Hydrogen’s one electron. It’s flips from spin up to spin down, and the energy difference is a photon at about 1420 MHz.

It’s called forbidden because it’s extremely unlikely to occur - so unlikely that I don’t believe it’s been observed in the lab. But in aggregate, with vast vast clouds of hydrogen it becomes likely enough and strong enough to detect.

We observe this emission from hydrogen in our own galaxy and through the local universe. And it’s quite strong to easily detect.

In this experiment, they’re looking for that same 1420 MHz signal, redshifted down to something like 180 MHz (where exactly it is isn’t known for sure).

There are 128 grids of 4x4 antennas. There’s nothing special about the 128 figure, and very soon it will be doubled - but there were also talks of a smaller upgrade too.

The 4x4 tile size is a compromise between sensitivity and field of view. 5x5 or 6x6 configurations would be much more sensitive to signal but at the expense of a much smaller field of view, since the field of view is formed using phased arrays. For imaging purposes actually we’d really like the smaller field of view, because it would make it easier to avoid nasty bright radio sources from washing out our observations, but for detecting this epoch if reinionization signal, the bigger field of view is better since it’s a global full-sky signal.

LOFAR uses 24 (or 48) per station for the "high" frequency tiles and 96 for the lower frequency ones if I'm not mistaken, so a power of two is not by definition required.

Probably a 64x64 grid.

I would have used that 3/4 times during the last year in a big EU city: we do consulting, and one of our customer is adamant their data cannot go on the public cloud. So they have their own data center, and some file sharing utility. Problem is, you need to go through their VPN, that is super slow, and their sharing utility closes connections after a while.

Result: transferring 30/40 GiB of data is painful, and we often go to their office to retrieve the data instead of using the Internet. In an ideal world, I wouldn't need a service like the one you suggest, but since a lot of our customers seems to be in the Stone Age, I would probably use it.

I have friends who do regular SSD file transfers. Mostly between different countries but sometimes in the same city.

They just use regular messaging services and simple of the shelf encryption software with out of bound key transfer (I.e email...).

Hardware encryption (and platform for key sharing and booking deliveries) could certainly be useful, but I’m not sure about the transport port. I feel like outsourcing it to normal transporters is more reasonable

Floating around doesn't do it justice....it's been flying at the speed of light away from its origin for the past 12 billion years until it ran into a little sensor.

Not likely. I worked at a research station right down the road from a zoo and we didn’t see any interference from any of the animals. Now, the security fence on the other hand? Static City we used to call it.