Observations suggest that the intergalactic gas in our universe is a little hotter than it should be. Recently, a team of astrophysicists have used sophisticated computer simulations to propose a radical solution: an exotic form of dark matter known as “dark photons” could be heating the place up.
These strange particles would be the carriers of a new, fifth force of nature that normal matter does not experience, but occasionally these dark photons can flip their identities to become regular photons, providing a source of heat.Feeling neutral
We could find such dark photons by observing the intergalactic gas using what’s known as the Lyman-alpha forest. When we observe light from a distant, bright object, like a quasar (glowing objects powered by black holes at the centers of distant galaxies), there is a series of gaps in an otherwise smooth spectrum of light from that faraway object.
Here’s why: that light has to filter through billions of light-years of gas to reach us. Occasionally that light will pass through a relatively dense clump of neutral hydrogen — a type of hydrogen that consists of one proton and one neutron, and which permeates gas clouds throughout the universe.
Most of that light will pass through unaffected, but a very specific wavelength of light will get absorbed. This wavelength corresponds to the energy difference needed to bump an electron from its first to its second energy level inside the hydrogen atoms.
When astronomers look at the light coming from that object, it will look otherwise unremarkable except for a gap at the wavelength of that specific energy transition, known as the Lyman-alpha line.
The light from the distant object will pass through multiple clouds and clumps of neutral hydrogen. The expansion of the universe causes the gaps to redshift to different wavelengths, with a new gap appearing at a different wavelength depending on the distance to the particular gas clouds.. The end result of this is the “forest”: a series of lines and gaps in the spectrum. Getting hot in here
These Lyman-alpha gaps can also be used to measure the temperature of each gas cloud. If the neutral hydrogen were perfectly still, the gap would appear as an incredibly thin line. But if the individual molecules are moving, then the gap will widen because of the kinetic energy of those molecules. The hotter the gas, the more kinetic energy the molecules have, and the wider the gap.
In a paper appearing in November in the journal Physical Review Letters, a team of astrophysicists have pointed out that by using this method, it seems that the clouds of gas that scatter between galaxies are a little too hot. Computer simulations of the evolution of those gas clouds predict them to be just a little bit colder than we observe, and so perhaps something is heating up those clouds that isn’t currently accounted for in our astrophysical simulations.
One possible explanation for this discrepancy is the presence of “dark photons” in our universe, the study authors claim. This is a very hypothetical form of dark matter, the mysterious, invisible substance that accounts for roughly 80% of all the mass in the universe, yet doesn’t seem to interact with light.
Since astronomers do not currently understand the identity of dark matter, the field is wide open with possibilities as to what it could be. In this model, instead of the dark matter being made of invisible particles (like a phantom version of electrons, for example), it would instead be made of a new kind of force carrier — that is, a type of particle that mediates interactions between other particles.A warm and fuzzy darkness
The familiar photon is the force carrier of electromagnetism – it’s what creates electricity, magnetism, and light. Dark photons would be a force carrier for a new force of nature that does not operate at the usual scales in the usual scenarios (for example, in our laboratories or within the solar system, where we otherwise would have already observed it).
According to the study authors, the dark photons would still have a tiny bit of mass, and hence they could still account for the dark matter. Plus, because they’re force carriers, they may also interact amongst themselves and with other potential dark matter particles. In the models investigated by the team of astrophysicists, the dark photons are capable of one more trick: they can occasionally turn into a regular photon.Related stories—From Big Bang to present: Snapshots of our universe through time
—The 18 biggest unsolved mysteries in physics
—The 15 weirdest galaxies in the universe
In physics terms, the dark photons can “mix” with regular photons, very rarely swapping identities. When they do, the newly created photon goes on to do what regular photons always do: heat things up. The researchers performed the first ever simulations of the evolution of the universe, including the effects of these sneaky shapeshifting dark photons. They found that a particular combination of dark photon mass and the probability of changing into a regular photon could explain the heating discrepancy.
This result is a very far from a slam-dunk case for the existence of dark photons. A range of possibilities could also explain the Lyman-alpha results, like inaccurate observations or a poor understanding of (normal) astrophysical heating between galaxies. But it is an intriguing clue, and the results can be used as a springboard to continue exploring the viability of this exotic idea.
It is raising new concerns in the global players’ union about whether the stars of the sport are being protected in hot and humid conditions.
FIFPRO has asked FIFA to allow cooling breaks every 15 minutes rather than just in the 30th minute of each half.
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There’s also a request for half-time to be extended from 15 to 20 minutes to help lower the core temperature of players.
FIFPRO’s medical director, Dr Vincent Gouttebarge, said: “There are some very challenging weather conditions that we anticipated a couple of weeks ago already, that was already communicated to FIFA.
“And I think the past few weeks were confirmation of all worries that the heat conditions will play a negative role for the performance and the health of the players.”
Football has seemed focused on players and fans baking in the Middle East – but scorching summers in Europe and the US are becoming increasingly problematic for sport.
Image: England are the tournament’s defending champions. Pic: AP
While climate change is a factor, the issue is not new and at the 1994 World Cup, players were steaming as temperatures rose in the US.
There is now more awareness of the need for mitigation measures among players and their international union.
FIFPRO feels football officials weren’t responsive when it asked for kick-off times to be moved from the fierce afternoon heat in the US for the first 32-team Club World Cup.
FIFA has to balance the needs of fans and broadcasters with welfare, with no desire to load all the matches in the same evening time slots.
Electric storms have also seen six games stopped, including a two-hour pause during a Chelsea game at the weekend.
This is the dress rehearsal for the World Cup next summer, which is mostly in the US.
Image: Players are also feeling the heat at the Club World Cup. Pic: AP
The use of more indoor, air conditioned stadiums should help.
There is no prospect of moving the World Cup to winter, as Qatar had to do in 2022.
And looking further ahead to this time in 2030, there will be World Cup matches in Spain, Portugal and Morocco. The temperatures this week have been hitting 40C (104F) in some host cities.
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Wildfires erupt in Italy and France amid heatwave
FIFA said in a statement to Sky News: “Heat conditions are a serious topic that affect football globally.
“At the FCWC some significant and progressive measures are being taken to protect the players from the heat. For instance, cooling breaks were implemented in 31 out of 54 matches so far.
“Discussions on how to deal with heat conditions need to take place collectively and FIFA stands ready to facilitate this dialogue, including through the Task Force on Player Welfare, and to receive constructive input from all stakeholders on how to further enhance heat management.
“In all of this, the protection of players must be at the centre.”
England are looking to defend their title at the 2025 Women’s Euros.
But conquering this year’s competition will be tricky right from the group stages.
The Lionesses will come up against Wales, who made history by qualifying for their first major tournament, and two other European heavyweights: France and the Netherlands.
Here is everything you need to know about Euro 2025.
Where is Euro 2025 being held?
This year’sWomen’s Euros is being held in Switzerland.
The competition kicks off on Wednesday 2 July, with the final on Sunday 27 July.
Matches will be held in eight venues across Switzerland from Zurich to Geneva, with the final game being played in Basel.
What teams have qualified?
A total of 16 teams have qualified for the competition.
Eight teams progressed directly from the qualifying league stage and seven teams qualified via the play-offs.
As hosts, Switzerland qualified automatically.
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Is it too hot for football?
The teams playing in the tournament are:
• England • Belgium • Denmark • Finland • France • Germany • Iceland • Italy • Netherlands • Norway • Poland • Portugal • Sweden • Spain • Switzerland • Wales
How much do the winners get?
This year, the total available prize money for the tournament stands at €41m (£34m) – more than doubling from the prize pot in 2022.
All competing sides receive a €1.8m (£1.5m) participation fee, with the remaining money going to the quarter-finalists, semi-finalists, runners-up and winners.
The maximum prize money achievable for the tournament winners, if they also win their three group stage matches, is €5.1m (£4.3m).
Image: England celebrate their victory at Women’s Euro 2022. Pic: Reuters
Who has (and hasn’t) made the England squad?
Some notable names will be missing from the England squad this year.
Goalkeeper Mary Earps announced in May that she is retiring from international football with immediate effect.
Within days, two other names, Fran Kirby and Millie Bright, also announced they would not be taking part in Euro 2025.
The departure of Bright, Earps and Kirby is a loss of three experienced players – between them they have 218 international appearances.
So who has manager Sarina Wiegman picked for the 23-person squad, and who has been snubbed?
Use our slider below to look through some of the key players, or see a list of the full England squad, here.
History-making Wales squad announced
The Welsh women’s national football team has qualified for an international tournament for the first time.
Their 23-player squad was announced by head coach Rhian Wilkinson at the summit of Yr Wyddfa (Snowdon) on Thursday morning.
Image: Rhian Wilkinson following the squad announcement at the summit of Yr Wyddfa. Pic: PA
Midfielder Angharad James captains the side, and is one of four players to have played over 100 times alongside fellow Wales veterans Jess Fishlock, Hayley Ladd and Sophie Ingle, who also made the cut.
Ingle hasn’t featured for club or country since suffering an ACL injury during a pre-season friendly for Chelsea last September.
The 33-year-old returned to full training at the beginning of the month and her inclusion comes as a significant boost ahead of Wales’ first major tournament.
Fishlock, Wales’ record appearance holder and goalscorer, will hope to add to her 47 international goals as she leads the line.
The side beat the Republic of Ireland 2-1 in a play-off match to secure their spot in the Euros.
Image: Wales have qualified for an international tournament for the first time. Pic: Reuters
Wales head coach Rhian Wilkinson said after the match: “This team found a way. They never broke for each other, they stayed strong. I’ve never been prouder of a team.
“This team stands on the shoulders of giants [the pioneering female footballers] who came before, and now they’ve proven how good they are.”
Similarly to the World Cup, teams in the Euros are split into four groups.
The top two teams in each group will progress to the knockout stage, where games will be decided by extra-time and penalties if needed.
The knockout stage pits the winners of the group against the runners-up, meaning Germany, Poland, Denmark or Sweden could lie in wait for England and Wales in the last eight.
Group A: Switzerland, Norway, Iceland, Finland
Group B: Spain, Portugal, Belgium, Italy
Group C: Germany, Poland, Denmark, Sweden
Group D: France, England, Wales, Netherlands
When are England and Wales playing?
The Lionesses start their bid for the Euros title on 5 July when they take on France. The game will take place in Zurich at 8pm UK time.
Wales kick off their campaign earlier the same day, against the Netherlands. That game starts at 5pm UK time in Lucerne.
The two nations will be the last teams in Group D to face each other.
Their showdown will be held in the city of St Gallen, on Sunday 13 July. Kick-off is at 8pm UK time.
Can England win the Euros again?
The Lionesses lifted the Euros trophy in front of a home crowd in 2022, after beating Germany 2-1.
Chloe Kelly delivered the deciding goal in extra time, but can the team do it all again?
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Can England win the Euros again?
Lucy Bronze admitted to Sky News that the team faces “one of the hardest” groups going into the tournament, but added: “We know on any given day, when we play at our best we can beat any team in the world.”
The right-back said: “We have got one of the most talented squads going into the Euros… I wouldn’t want to be a defender on the other team going against some of our players.
“We know it is going to be difficult, there are maybe a handful of teams that are capable of winning it, and we are definitely one of them.”
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‘Handful of teams could win the Euros – we’re one’
After naming her squad in May, Weigman told Sky News sports correspondent Rob Harris: “This group is a very well-balanced mix of players with multiple tournaments on their CVs and also those that will make their tournament debuts.
“I am excited to see what we are capable of this summer.”
How to watch the Euros 2025
Eevery single match of the Women’s Euros will be shown across the BBC and ITV, with the two broadcasters showing half of the 31 matches each, except the final, which will be shown on both channels.
Every match will also be screened live at three venues across London and Birmingham.
TOCA Social at The O2 and Westfield White City in London and The Bullring in Birmingham is hosting watch parties for fans hoping to catch all the action.
A flight in Australia was delayed for two hours after a stowaway snake was found in the plane’s cargo hold.
The reptile was found as passengers were boarding Virgin Australia Flight VA337 at Melbourne Airport bound for Brisbane.
Snake catcher Mark Pelley said he thought it could be venomous when he approached it in the darkened hold.
Image: The snake in the cargo hold. Pics: Mark Pelley
But it turned out to be a harmless 60cm green tree snake.
“It wasn’t until after I caught the snake that I realised that it wasn’t venomous. Until that point, it looked very dangerous to me,” Mr Pelley said.
He said when he entered the cargo hold, the snake was half hidden behind a panel and he feared it could flee deeper into the plane.
“I had one chance to grab it, and if it escaped past me it would have gone into the panels, and then that would have been extremely hard to catch,” he told Sky News.
“Snakes are very fast-moving, thin and agile,” he added.
Mr Pelley said he told an aircraft engineer and airline staff they would have to evacuate the aircraft if the snake disappeared inside the plane.
“I said to them if I don’t get this in one shot, it’s going to sneak through the panels and you’re going to have to evacuate the plane because at that stage I did not know what kind of snake it was,” he explained in a separate interview.
“But thankfully, I got it on the first try and captured it,” he added. “If I didn’t get it that first time, the engineers and I would be pulling apart a [Boeing] 737 looking for a snake still right now.”