OrbitalHub

The source flagged on December 10, 2023 looked ordinary at first: a flat-spectrum radio quasar in the constellation Canes Venatici, sitting just shy of a redshift of 1, where most extragalactic work stops being feasible. Within four nights of follow-up, the prototype Large-Sized Telescope (LST-1) on La Palma had pulled it out of the background with a statistical significance of 12 standard deviations, and a few nights later the MAGIC telescopes at the same observatory confirmed the detection at 6 standard deviations. The result, published in August 2026 in Astronomy & Astrophysics by the CTAO LST and MAGIC collaborations, makes OP 313 the most distant active galactic nucleus ever detected at very-high-energy gamma rays (above 100 GeV) and only the tenth flat-spectrum radio quasar (FSRQ) ever caught at those energies (Abe et al. 2026, A&A).

Blazars are what happens when a supermassive black hole happens to be pointing one of its relativistic jets almost directly at Earth. The jet accelerates particles to extreme energies, and the blazar we see is the Doppler-boosted glow of that jet. The lower-energy bump of that glow peaks somewhere in the optical or X-ray range, and a second, much higher-energy bump sits in the gamma-ray range. For BL Lacertae objects, the second bump can be tracked cleanly all the way up to tens of tera-electron-volts with imaging atmospheric Cherenkov telescopes (IACTs). For FSRQs, where the jet is embedded in bright gas clouds and a dusty torus, that same very-high-energy glow is much harder to produce and gets eaten on the way out.

The "eaten on the way out" part is what makes OP 313 a hard target. Every gamma-ray photon at, say, 300 GeV that leaves an FSRQ has to traverse roughly seven billion light-years of space to reach us, and along the way it can pair-produce on infrared and optical background photons left behind by every star that has ever lived. That fog, the extragalactic background light (EBL), gets thicker as you look deeper into the universe, and very-high-energy photons from distant blazars usually arrive at Earth with their high-energy tail statistically removed. OP 313 at z=0.997 sits deep enough in this fog that detecting its very-high-energy emission at all was the main challenge; using it to constrain the fog itself is the secondary prize (phys.org news writeup, 24 August 2026).

The detection was triggered by a high state reported by the Fermi-LAT and optical monitoring networks in late November 2023. Once the daily Fermi analysis (the FLaapLUC pipeline) flagged the rising flux, two follow-up alerts went out on December 10, and both LST-1 and MAGIC began observing that same night. Between December 10 and December 19, LST-1 accumulated 14.6 hours of good-weather data and detected the source at 12.0 standard deviations above ~10 GeV, the highest single-instrument significance the campaign produced. The MAGIC stereo system collected 10.4 hours during the same flare window and confirmed the detection at 6.0 standard deviations. Follow-up in January 2024, when the source had dropped back into a low state, returned only upper limits, consistent with a flaring source that had settled back down (Abe et al. 2026, A&A).

The paper's value goes beyond confirming one more extragalactic source. OP 313 had been observed before in the very-high-energy range by MAGIC alone and produced only upper limits, so the new detection, which doubled as a first-light demonstration for the LST-1 prototype that will seed the Cherenkov Telescope Array Observatory (CTAO) in the Northern Hemisphere, slots the source into the small club of VHE-detected FSRQs (TeVCat catalogue for OP 313). The previous record-holder at this kind of energy was a different FSRQ called PKS 0346-27, at redshift 0.991. Pushing that mark to 0.997 by no more than a sliver of z amounts to several extra billion years of lookback time at this distance, where each tick of z adds roughly a billion light-years of optical depth through the EBL.

The detection also slots into a wider multimessenger story. In May 2012, the IceCube Neutrino Observatory at the South Pole recorded a high-energy track-like event whose reconstructed direction was consistent with the position of OP 313. The neutrino was not temporally coincident with the gamma-ray flare, so this paper cannot claim a coincident detection; but the fact that the same source is now visible at the highest gamma-ray energies, in the same sky region IceCube flagged, raises the long-term odds of catching a genuine neutrino-blazar coincidence during a future high state (LAPP press release, 2024).

LST-1 is the first of four Large-Sized Telescopes planned for the northern Cherenkov Telescope Array Observatory (CTAO) array, situated next to MAGIC at the Roque de los Muchachos Observatory on La Palma in the Canary Islands. Its 23-metre segmented mirror dish and its 1,855-pixel camera of high-quantum-efficiency photomultiplier tubes give it a low energy threshold of roughly 20 GeV, low enough that any VHE source that drifts overhead is within reach. MAGIC, the older neighbour, is a stereo pair of 17-metre dishes; together they cross-check each other's energies and directions, which is why the LST-1 paper and its Table 1 quote both sets of numbers.

Detecting OP 313 was a threshold problem on both instruments. LST-1 reached 12.0 sigma in the December window but with an analysis threshold of about 60 GeV, where the gamma/hadron separation is intrinsically harder for a single dish; the per-cent signal-to-background level reflects that the measurement is background-limited near threshold. MAGIC, with stereoscopic reconstruction, ran warmer at a threshold of about 70 GeV and reached 6.0 sigma, but its higher absolute flux above 100 GeV put it above background-systematic-limit. The two spectra agree, within their stated uncertainties, on a simple power law with no strong sign of intrinsic curvature (Abe et al. 2026, A&A HTML).

A common background light hides in those measurements. The cumulative infrared-to-ultraviolet glow of every star that has ever existed, the EBL, attenuates very-high-energy photons in a way that grows with redshift. To turn the OP 313 detection into an EBL measurement, the team fit the joint Fermi-LAT and LST-1 spectrum with a spectral model multiplied by exp(-α τ), where τ is the optical depth predicted by a reference EBL model (Saldana-Lopez et al. 2021) and α is a free scaling factor. They then constrained α by likelihood ratio testing. The result: α(95%) < 1.14 from the LAT plus LST-1 dataset, and tighter upper limits in the optical band, with the most stringent constraint coming between about 0.325 and 1.069 micrometres, the so-called Cosmic Optical Background. At 0.6 micrometres, the upper limit lands at 6.72 nanowatts per square metre per steradian (statistical, 95%), or 8.74 with energy-scale systematics included (Abe et al. 2026, A&A).

OP 313 has a separate history worth noting. Originally catalogued as a variable star in 1959 (the OP 313 designation is a positional reference), it was later identified with a flat-spectrum radio source (B2 1308+326) and reclassified as a quasar at z ≈ 0.997. The early literature sometimes labelled it a BL Lacertae object; current multi-wavelength studies favour the FSRQ classification because its emission lines and broad-line-region signatures are visible when the source is in a high optical state (Wikipedia - B2 1308+326, companion A&A study, March 2026).

OP 313 is now the highest-redshift AGN detected at very-high-energy gamma rays, the tenth FSRQ caught at those energies, and a useful lever on the optical part of the extragalactic background light. LST-1's first confirmed contribution to extragalactic astronomy came with the same paper that moved the VHE distance record. The CTAO Consortium plans to complete the northern array over the next several years; with four LSTs at low threshold and several mid-sized telescopes at higher energies, the arrival-time window for catching the next record-breaker will keep getting shorter.

Abstract

The blogpost explores relativistic effects on proof-of-work based cryptocurrency protocols. Cryptocurrencies are here to stay and it is quite plausible that future human colonists spread across the solar system and beyond will use a decentralized cryptocurrency as opposed to a fiat currency issued by a central authority. The low transaction fees, the ubiquitous access, not being bound by exchange rates or interest rates, not being controlled by financial institutions who are serving foreign interests -- these are some of the advantages cryptocurrencies will enjoy in the thriving exo-economy.

Motivation

At present, on a cryptocurrency network, the information exchanged by the nodes in the network reaches each node almost instantaneously. The speed at which the TCP/IP packets travel on the network and the fact that the Internet spans only the Earth and the LEO makes this possible. However, once the region the network is spread across will reach certain boundaries, the network size would have negative impact on the network: increasing communication failures due to network delays, more frequent and longer blockchain forks as part of the proof-of-work protocol, network segregation into local sub-networks (let us call them topological forks), just to name a few.

Nullius in verba... as they say. Let's go deeper into details and figure out a feasible solution for a truly interplanetary cryptocurrency.

Cryptocurrency 101

You can think of a cryptocurrency as a digital money ecosystem. Plain and simple. A collection of technologies are part of this ecosystem, all of them the result of years of research in the cryptography and distributed systems fields: a decentralized network of computers, a public transaction ledger -- also known as a blockchain, a protocol that consists of a set of rules for transaction validation, a decentralized consensus mechanism. [ANTO]

A decentralized network of computers ensures the resilience of the network. We can think of both computing power and data storage capabilities. As the computing power is distributed across the network, any disruption can be successfully handled by the network. Transaction data resides on all nodes of the network. This implies that even physical damage done to network nodes will not take out the network.

The blockchain is a public distributed ledger which stores all transactions handled by the network. As the name suggests, the blockchain is a list of data blocks. Each of these blocks contains a set of transactions, as many as can fit in the block, given the maximum size of the block (a characteristic of the network). Transactions contain sender and receiver info, and the amount/asset that is changing ownership, and they are broadcasted and added to blocks by network nodes. Blocks are linked to the previous block in the chain by a cryptographic hash (the hash of the previous block becomes part of the current block). This backward link leads all the way to the first block in the chain, the Genesis block. Each cryptocurrency blockchain has one. The cryptographic hashes have an important role in protecting the blockchain from tampering attempts.

The transaction validation rules enforced by the nodes in the network ensure that the content of each block in the blockchain is valid. By far, the most frequent form of fraud is double spending. The validation process makes sure that the inputs on the transactions exist and that they have not been already spent. The transactions marked as invalid are rejected by the network and do not make it on the blockchain.

The consensus mechanism is designed so that all the nodes in the network can agree on the set of transactions to be included in the current block. It shifts the authority and the credibility required by a central clearing house to a network of nodes. Important to mention here that, inherently, the nodes do not trust each other, and they do not have to because the trust is enforced by the consensus mechanism itself.

The Proof-of-Work

We mentioned above that one of the key innovations that make cryptocurrencies possible is the decentralized consensus mechanism. Currently, the de facto consensus mechanism is the proof-of-work.

The proof-of-work consensus mechanism was proposed by Satoshi Nakamoto in 2008 [NAKA]. In general, a proof-of-work is a piece of data that requires costly and time consuming computational effort, but it is very easy to verify. A very good analogy is one of your semester projects in college... it takes you a whole semester to finalize it, but it takes very little time and effort for your supervisor to evaluate and grade it. Similarly, proof-of-work is used by cryptocurrencies for block generation. For the network to accept the block, nodes must complete a proof-of-work which also guarantees the integrity of the transactions included in the block. The difficulty of the proof-of-work is adjusted by the network so that a new block can be generated every fixed time interval. This fixed time interval is characteristic to every cryptocurrency. Most notably, for Bitcoin this time interval is set to 10 minutes.

Satoshi Nakamoto's solution, emobodied by the proof-of-work algorithm above, achieves consensus on the network without a central trusted authority (hence the name decentralized consensus mechanism).

Enter the Ansible

For the astute reader, it is quite obvious at this point that communication delays between the network nodes have a direct effect on the protocol described above. An important assumption made when the protocol was designed is that these delays are small, and this is why they can be handled by the network when the nodes choose to follow and validate the blocks on the longest blockchain fork. Also, this is the reason why all the nodes in the network can have a say in the network consensus. They all can find a solution for the current block, and they all can be rewarded when they find the solution. The communication delays witnessed by the peripheral nodes will cripple their ability to find solutions and these nodes will not be incentivized to remain in the network. Hence, the segregation of the network effect mentioned earlier.

Unfortunately, given the current technological level of our civilization, we do not have at our disposal a technology that allows us to communicate fast and reliable over the large expanse of space. It would take a hell of a wait time to proces a payment made by a mining corporation in the TRAPPIST-1 system, 12 parsecs within the constellation of Aquarius, to a planetary engineering corporation located in the Sol system... twice 39 years plus the block confirmation time.

Fortunately, the Sci-Fi literature already offers a solution for our problem. For those of you, Sci-Fi nerds like myself, that have already read Rocannon's World [LEGU] and Ender's Game [CARD], the Ansible device must sound very familiar. The ansible is a fictional device capable of faster-than-light communication. To word this differently, an operator of such device can send and receive messages to and from another device over any distance with no delay.

Hence, even if only in the realm of science fiction, we will be able to devise a solution for the problem that the future cryptocurrency enthusiasts, living in the outer space colonies, will eventually face.

The Special Relativity Theorem

Before elaborating more on a required upgrade of the network protocol, we have to discuss the special relativity theorem and its implications on how time and distance are perceived in reference systems.

Albert Einstein was awarded the Nobel Prize in Physics in 1921. He received it for his contributions to the understanding of the photoelectric effect, after publishing a paper on it in 1905. At that point his contributions to the understanding of gravity through his theory of relativity were well known, but the new perspective on gravity offered by Einstein's theory was so controversial that the Nobel Prize Committee members chose to protect their reputation. They decided that it was appropriate to award Einstein the Nobel Prize for "his services to theoretical Physics, and especially for his discovery of the law of the photoelectric effect."

During his research Einstein attempted to reconcile the principle of relativity with the principle of the constancy of the velocity of light. This attempt led Einstein to the discovery of the special relativity theorem. Einstein's Gedankenexperiment (thought experiment) with a test subject travelling by train is very well known in the scientific community. If our human subject is walking towards the front of the train with velocity w with respect to the train, and the train is moving with velocity v with respect to the embankment, then an observer on the embankment will measure as W = v + w the velocity of our subject on the train. If instead of our traveller, we consider a beam of light propagating with velocity c, the velocity measured by the observer on the embarkment would be v + c. However, this violates the principle that the velocity of light is constant in any inertial reference system and equal with c. Einstein found a solution for this problem and thus resolved the incompatibility.

One direct consequence of the special relativity theorem is the Lorentz transformation.

Before the relativity theorem, time in physics had an absolute significance, independent of the state of motion of the reference system. However, every inertial reference system has its own particular time. We always have to be told which inertial reference system the statement of time refers to. If you look at your watch, the time you read is the time as measured in the Earth inertial reference system. By the way, the Earth circles the Sun on an almost circular orbit, which means that any body maintaining a constant position in the Earth reference system should experience some centripetal force. However, this centripetal component is negligible compared to the gravitational pull of the Earth. Hence, engineers use this aproximation when calculating satellite orbits.

Back to our original trail of thoughts... the axiom that lays the foundation for the Lorentz transformation states that every ray of light possesses the velocity of transmission c relative to any inertial reference system. That is the velocity of transmission in vacuo (in a vacuum).

If following Einstein's thought experiments [EINS], the above-mentioned axiom leads to a set of four equations that explain the relation between dimensional and temporal coordinates in two inertial reference systems:

  x' = (x - vt)/sqr(1 - v²/c²)
  y' = y
  z' = z
  t' = (t - x*v/c²)/sqr(1 - v²/c²)

where:

 x, y, z, t coordinates in inertial reference system K,
 x', y', z' , t' coordinates in inertial reference system K',
 v the relative velocity between inertial reference systems;

also, the expression 1//sqr(1 - v²/c²) is known as the Lorentz factor.

The Lorentz transformation equations are a more general case of the Galilean transformation:

  x' = x - vt
  y' = y
  z' = z
  t' = t

which is the basis of the assumptions of the classical mechanics as to the absolute character of both dimensional and temporal coordinates. The above are the result of replacing velocity c with ∞ in the Lorentz transformation equations.

The Lorentz transformation has a few corollaries which have an impact on time dilation, length contraction, relativistic mass, relativistic momentum, and relativistic kinetic energy. The one that concerns us is the time dilation corollary:

 Δt = γΔt'
 
where γ is defined by

 α = 1/γ = sqr(1 - v²/c²)

Assuming a clock at rest in inertial reference system K, and moving with the velocity v in the inertial reference system K', the time Δt' between two ticks as measured in the frame K' is longer than the time Δt between the same ticks as measured in the rest frame of the clock, K.

Relativistic Effects on Proof-of-Work

To better understand the relativistic effects on how relative time is perceived in two inertial reference systems (or Galilean reference systems [EINS]) we have to mention the twin paradox. The twin paradox is a thought experiment that involves two identical twins. One of the twins makes a journey into space onboard a relativistic spaceship, and upon his return to Earth discovers that his twin has aged much more than he did. Depending on how fast the spaceship moves through space and/or how long the journey was, our traveller could return to Earth and realize that several generations have passed meanwhile.

As a direct application of the twin paradox, we have Mazer Rackham, International Fleet Admiral and Ender Wiggin's mentor, as portrayed by Orson Scott Card [CARD]. The fighter pilot who destroyed the Formic Fleet Flagship, killed the Hive Queen, and ended the Second Formic Invasion, Mazer Rackham is sent on a journey on a relativistic spaceship and returns to Earth 100 years later in order to assist the International Fleet. Upon his return he has barely aged a few years.

Similarly, if a subnetwork is moving relative to the rest of the network, the nodes in the subnetwork would experience time dilation as predicted by the special relativity theorem. Hence, they are at a disadvantage compared to the rest of the nodes because they have less time available to find a solution for the proof-of-work problem. In order to make thing square for all the nodes in the network, the difficulty of the problem should be adjusted in each subnetwork using the Lorentz factor: in order to compensate for time dilation, the relativistic nodes should have to solve a simpler problem. Also, their block confirmation time should decrease as well.

One element is missing still... how do ansibles synchronize? What value has the Lorentz factor for each one of them? One simple solution for this problem is having one of the ansibles (let us say the Earth-bound one) broadcasting a beacon every fixed number of seconds. The ansibles interfacing to subnetworks would pick up the broadcast, and by measuring the time interval between the beacons, infer the Lorentz factor. Once the Lorentz factor is determined, the nodes mining on the subnetworks will have their proof-of-work difficulty and the block confirmation time adjusted accordingly.

A more Down-to-Earth Solution for the Problem

We will fork the storyline (pun intended) at Enter the Ansible paragraph, and suggest a more down-to-earth solution for the problem. The peripheral nodes are not to participate in the consensus. Their function would be just to relay messages (a.k.a. payment information) across the network. In our multi-planetary scenario, the nodes working on the proof-of-work would reside on/around the Earth, and the network nodes on Mars or any other region in the Sol system would have to wait 2x (network packets travel time) + (block confirmation time) in order to confirm a payment. However, such a solution would have an Achilles heel very hard to defend... if starting its mining engine, any peripheral node could take over the local network and force a topological fork of the network. For a node, the incentive of staying honest on the current network must be stronger than any reward obtained by cheating.

Concluding remarks

While the blogpost contains some elements of fiction, it accurately describes the cryptocurrency ecosystem, the special relativity theorem, the Lorentz transformation and its corollaries. We would like to thank the readers that went through this exercise with us. Undeniably, cryptocurrencies are disrupting the global economy and they are here to stay. Undeniably, we -- as a species -- will explore and migrate farther than the LEO. History has taught us that decentralization is the key to survival and prosperity. Let us together make the future happen.

References

[ANTO] Antonopoulos, Andreas M., Mastering Bitcoin, Second Edition, O'Reilly Media, Inc., June 2017;
[CARD] Card, Orson Scott, Ender's Game, A Tor Teen Book, 2014;
[EINS] Einstein, Albert, Relativity, The Special and the General Theory, Princeton University Press, 2015;
[LEGU] Le Guin, Ursula K., Rocannon's World, Harper & Row, 1977;
[NAKA] Nakamoto, Satoshi, Bitcoin - A Peer-to-Peer Electronic Cash System, www.bitcoin.org, 2008;