China's new high-speed train doesn't roll along railways, it flies through tubes.
There are hopes it will one day connect cities and villages across the country, running at speeds of up to 4,000 kilometres per hour.
The magnetic-levitation (or maglev) train can clock speeds of 623 kph in tests — almost 200 kph quicker than the fastest train in service.
It is yet to be rolled out, but in February it went even faster, during a test of technology crucial to the train's high speed.
For the first time it travelled stably through the 2-kilometre low-vacuum tube, according to China's state run Aerospace Science and Industry Corporation (CASIC).
CASIC is yet to reveal the speed it reached, but said it was faster than its previous record of 623 kph.
How does the train go so fast?
Magnets!
The train is moved and suspended above the ground using magnetic-levitation technology — basically using the push and pull forces of magnets to guide, speed or slow the train.
This means the maglev train is much lighter, as it doesn't need wheels and brakes and other heavy bits of engineered steel to keep it safely on a railway.
To help keep friction down, China's latest superconducting maglev train is suspended, using three types of magnets, in a low-vacuum pipeline to "fly".
This generation is designed to reach up to 1,000 kph — faster than most people will ever travel on an airplane.
Unless you're Taylor Swift, whose private jet can still outpace the maglev train … just.
What are the main challenges?
UK high-speed rail expert Professor Andrew McNaughton told the ABC there were several difficulties in building large maglev networks.
Firstly, all new infrastructure, like the low-vacuum tunnel in China, has to be built and no older trains or railways are compatible.
Secondly, the energy requirement is "very substantial", Professor McNaughton said.
"The third is that the volume of people between just two destinations is insufficient to justify the cost — unless it is two mega cities," he explained.
"Various studies have suggested that the construction and operational cost of maglev is probably four to five times that of a conventional high-speed railway."
Because of the velocities involved, noise is a big problem and means additional measures, like expensive tunnels and sound barriers, would need to be installed around communities.
"Lastly, whilst a maglev can operate around 500 kph compared with a conventional high-speed train at 350kph, the time saved — unless over a very long distance — is not huge and certainly not enough to justify the cost," Professor McNaughton said.
How will a train this fast change things?
Commuters can come into cities from further away, and the increased speed of logistics will be a boon for most businesses.
Because the train is capable of going up to 1,000 kph, there are other positives too.
When that kind of speed can be reached, trains can basically compete with planes.
A train capable of the high-speeds China is aiming for would likely have a big impact for a large country, said associate professor Jonathan Couldrick from the ANU College of Engineering, Computing and Cybernetics.
"Imagine commuting 400 kilometres in around half an hour — that would be a game changer for the population centres," he told the ABC.
"And so you can actually have growth areas away from the capital cities, and people commute in in the morning."
Mr Couldrick said the fast trains could also be better for the environment.
He has estimated that completely replacing regional passenger aircraft with ultra-high-speed trains in some countries where people have to travel vast distances could reduce carbon emissions by 3 or 4 per cent.
Designers want to push the limits of the train and Mao Kai, the technical chief of the project, told Chinese media it could ultimately reach a blistering 4,000 kph.
That's even faster than the record 3,529.6 kph reached in 1976 by the almighty SR-71 Blackbird reconnaissance aircraft — the fastest manned aircraft in history.
How does it compare to other high-speed trains?
In places like Japan and France, high-speed trains have been around for decades.
Since 2010, about 10 countries have developed high-speed trains — ones that can travel more than 250 kph.
But they run on railways and can't achieve speeds much beyond 350 kph, railway expert Associate Professor Philip Laird from the University of Wollongong told the ABC.
Except for the TGV in France, which holds the record for the fastest commercial train on steel wheels.
In special test conditions, a modified version can race along at 574.8 kph, but with passengers aboard it usually operates at speeds of about 320 kph.
The Shanghai maglev currently holds the record for the fastest train in service.
At 460 kph, the 30-kilometre journey between Shanghai's Pudong airport and Longyang Road station takes only about seven and a half minutes.
Japan's fastest bullet train can hit a maximum speed of about 320 kph, Dr Laird said.
But Japan also has a 42-kilometre test track on which it has run a maglev train at 503 kph, but that train is not expected to be in service until 2030 at the earliest, according to Dr Laird.
When Japan's new generation of maglev trains rolls out, they are expected to run at maximum speeds of 500 kph between Tokyo and Nagoya.
In October, Indonesia unveiled a high-speed railway that runs for about 150 kilometres between Jakarta and Bandung.
With maximum speeds of 350kph, the Whoosh is the fastest railway line in South-East Asia and was built by China at a cost of about $7.65 billion.
India has also been hard at work building a high-speed train between Mumbai and Ahmedabad.
It is due to be opened by 2027, Dr Laird said.
Could maglev connect Australia's distant cities?
Australia has been looking at connecting cities with high-speed rail for about 40 years.
Despite the huge costs involved with acquiring land and building the network, the High Speed Rail Authority (HSRA) was created last June to take the idea from paper to reality.
The federal government has also committed almost $80 million to the greatly anticipated high-speed rail line from Sydney to Newcastle.
Whether they would be keen to take it a step further and build a maglev rail remains to be seen, but Dr Couldrick is sceptical.
He estimated the cost to construct a maglev system in Australia would be, conservatively, about $1,000 per metre — for the magnets alone.
"That's $1 million per kilometre, on top of all the other infrastructure costs" he said.
"The cost–benefit may not be there"
Dr Laird said he was optimistic Australia would one day have a high-speed rail network, but it would take a while to construct.
He also was unsure about the likelihood of a maglev system but believes a high-speed rail network could be built incrementally.
"This has been the case in Japan — it started off with just over 500 kilometres (of high-speed railway lines) in 1964," he said.
"Now they have about 3,000 kilometres."
Professor McNaughton said the only place where a maglev would make sense would be between Brisbane, Sydney and Melbourne.
But, because maglev needs entirely new infrastructure and cannot run on existing lines while its dedicated track is built, the whole network would have to be completed before the first train could run.
"That's one heck of an infrastructure project," he said.
"If there are barely enough people travelling to justify high-speed rail — four planes an hour is one high-speed train, really — then justifying maglev at several times the cost isn't going to be remotely likely."
