I’d pay more for bbc content than i do for Netflix or prime. It’s typically very good content that is strongly geo locked behind iplayer and you have to play whack a mole to get it…
If you think this is bad, then the chemicals used in rocketry - read the book ignition [1] - will have you whimpering in a corner. As with any system, risks can be identified and controlled and operationalised - Gasoline has its risks, so does Chlorine trifluoride [2]. Yet both are wildly different and are used in day to day operations.
Yes rocketry has made very dangerous chemical. And hydrazine is used in other fields too. But it’s used because there aren’t safer alternatives that are fit for purpose.
Ammonia is being pushed as a predatory delay strategy. The article hints at this when it talks about the engines being dual-fuel (ammonia and methane). Given the massive price difference between green ammonia and methane it doesn’t take a genius to know what their next message will be “our ships are ammonia ready, we will run them on methane until the ammonia supply chains are ready then we’ll transition to it”. Expect they have no intention of transitioning.
The ships are “ammonia ready” in the same way my driveway is Ferrari ready. All that’s missing is a lot of other people’s money.
I think that’s not a good comparison. I think we generally accept that leaving the planet is inherently riskier than traveling on it. You have to generate enough energy to exit the atmosphere, that’s a shitload of energy. Of course it’s dangerous. We’ve been sailing relatively safely for thousands of years, though.
Same thing in Kenya. A 150km radius around Nairobi is maxed out. I have a fishy kit that can’t join due to capacity issues. In fact, the advent of Starlink - which had acquired 0.5% of the entire market - has rattled the existing players so much that, 1. They’ve doubled available bandwidth for residential plans without increasing cost. Safaricom went way overboard and 5x-ed plans. So if you were on 40mbit for $40 USD, you’d get 200mbit for the same cost. 2. They are all writing letters to the fcc equivalent crying about GSM spectrum interference (duh…) and predatory pricing [1]. I’m all for more competition! I’m only considering moving to Starlink due to frequent fibre cuts.
Interesting, because in principle they don't need to bother so much. Starlink doesn't actually have the capacity to provide that kind of connection to everyone in a densely populated area, there are underlying limits to how much bandwidth they can provide to a given area, so it's not given at all that they will be able to grow drastically beyond that 0.5% or so (I wouldn't be surprised if they can get a bit more capacity, but it's just not likely to be able to meet even a large fraction of the demand).
> it's not given at all that they will be able to grow drastically beyond that 0.5% or so
In a country with 33% internet penetration [1], that’s 1.5% of the market. And the top 1.5% of the market can easily be more than 10% of the profits in the market.
Can you help me understand the fundamental limitations?
I remember people saying that about cell phone networks but clever engineering has meant more and more capacity (and bandwidth) in spite of the laws of nature.
The issue is, there just aren't that many satellites in orbit. 7000 (for SpaceX, less for other networks) for the globe means that only a few connections over a particular geographical area end up causing serious congestion.
SpaceX is pushing hard to address this - they'll probably end up launching ~135 times this year, and are aiming for more than 180 times next year[2], most of which will be Starlink. But no matter how many satellites are in orbit, there just won't be the bandwidth to service dense urban areas.
The reason that cell phones work is because there are so many cell towers. And, those towers have a density that correlates with demand.
The problem with LEO satellites is, they have to evenly cover the Earth[1]. Which means that a level of service sufficient for a dense urban area would mean that rest of the world would be ridiculously over provisioned.
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1. It's more complicated than that. Specifically, providers can use inclination to limit orbits to mid latitudes. But that only helps so much.
2. These numbers may not mean much to you, but they are absurd compared to pre-SpaceX years. SpaceX is doing more launches in a year than most rockets do in their entire lifetimes. A normal year for a SpaceX competitor like ULA is 4-10 launches, although those companies are also aiming to ramp up as Starlink competitors like Kuiper demand more launch volume.
In any given place there are 3-4 Starlink satellites visible at a time. The bandwidth on each is somewhere in the 20 Gbps range.
So if you have 200 people using one satellite that’s no problem. 800 people using that whole cluster of visible satellites is also no problem. With 8000 simultaneous users you’re all down to 10 Mbps which is starting to get a bit limiting.
Each satellite covers an area about 15 miles across. About 100 square miles.
So… that works out to… something like 100 simultaneous users per square mile max.
That’s all back of the napkin math obviously… 1000 users packed into a small city surrounded by corn fields would be fine. 1000 users around every subway stop in NYC wouldn’t work even if the density is the same.
We've known how to efficiently broadcast TV programs to hundreds of millions of viewers simultaneously over satellite for decades now – in fact, that's how it all started :)
I wonder how hard it would be to add multicast capabilities to Starlink? Receivers could even cache popular content on a client side disk the way e.g. US satellite TV operators do for local ad insertion.
Good point about multicast - BT use it in the UK on their fibre/ADSL network to deliver live TV to their set-top boxes. I have never understood why it's not supported cross-ISP.
I believe it's very hard to implement across networks in a way that does not require core routers to become quite stateful and/or risks flooding parts of the network with multicast data nobody asked for.
There was a short conceptual revival of the multicast idea as an overlay network on top of unicast IP, under the banner of "content-addressable networks", but I haven't heard anything about that in a while.
How would Starlink (the Ka band service) interfere with GSM frequencies?
Or is that about the new "direct to cell" product? Is that even being launched near Kenya (presumably it'd not emit anything over areas it does not have a license in)?
Precisely,Safaricom also alleged that they would allow for illegal connections… perhaps they meant connections that we can’t easily wiretap on behalf of the government. Interestingly, during the protests a few months ago, the government severely throttled all external connections by putting a few interfaces down at the fibre sea landing points. Only Starlink users were getting good connectivity. A lot of folks migrated at that point.
Yes in a vague sense. And No in a strong practical sense.
Lensing works in reverse except for time delays which make the idea much more complex. The object's past is projected to us now, but our past would be projected to somewhere that the far object no longer occupies. Double lensing makes this even less reversible.
When the light we are now seeing was emitted, the lensing wasn't in place. In fact, the galaxies doing the lensing hadn't even evolved to the state that we see them in.
So if we sent a response to what we see now, it wouldn't make it back to the lensed objects.
That's just for single lensing. Double lenses are a massive coincidence of events at 4 points in time and space (emission, first deflection, second deflection and observation). That means that light going the other way wouldn't have the two intermediate points in the right place at the right times so it all breaks down for us and the object we see. There are some points that would be double lensed in the reverse direction but the locations and times for the source and observer have only very vague correlation to our location and the location of the object we see.
A simpler answer is just what happens if you look thru a telescope or binoculars "the wrong way" (backwards). The correct way shows a "zoomed in" view of that you're viewing, but looking the wrong way shows a "zoomed out" view.
So lifeforms on the other end of this cosmic "lens[es]" cannot use it to see us better, because in fact it makes us look further away from them than we are, from their perspective.
If I understand right, objects further than a redshift of z ~= 1.8 can't be reached by any signal we emit, and the second galaxy is at a redshift of z = 1.885. But I don't know how precisely (standard deviations rather than decimal places) the distance to the outbound cosmological horizon is being approximated, so it might be reachable by a signal sent by us:
The question I addressed is "does the lensing work the same from the other end". It's a very specific and clear question, and the answer is "no it does not", because if you reverse a telescope lens you get the opposite effect (from zoom-in to zoom-out)
The question of at what distance and relative velocity are the two locations so far apart that light can never make it from one to the other (due to expanding universe) is a completely separate issue.
While its allowed by the standard, its not something that is often used. Certainly the AppleTV that I use does not even offer an option to share its network connection over Ethernet. And I’m not aware of any other box that does.
Pretty sure you need a special cable that carries ethernet, as well as a device at the other end that supplies ethernet to HDMI, so you have to really want to let your "smart" tv to have access to the internet.
