Is our fundamental reality continuous or is it chopped up into tiny, discrete bits?
Asked another way, is space-time smooth or chunky? The question cuts to the heart of the most fundamental theories of physics, linking together the way space and time intersect with the material of our everyday existence.
However, experimentally testing the nature of space and time has been impossible, because of the extreme energies needed to probe such tiny scales in the universe. That is until now. A team of astronomers has proposed an ambitious new plan to use a fleet of tiny spacecraft to detect subtle changes in the speed of light, a hallmark of some of the most mind-bending theories of the cosmos. If space and time are indeed broken up into little bits, the research could pave the way for a completely new understanding of reality.
Related: The 18 Biggest Unsolved Mysteries in Physics
The question of "what is space and time?" goes back thousands of years, and our modern understanding rests on two strangely incompatible pillars: quantum mechanics and Einstein's theory of general relativity.
In general relativity, space and time are woven together into the unified fabric of space-time, the four-dimensional stage that underpins our universe. This space-time is continuous, which means that there are no gaps anywhere; it's all a smooth texture. Space-time isn't just a platform for us to act our parts, however; it's also a player too: The bending and warping of space-time gives us our experience of gravity.
Related: 8 Ways You Can See Einstein's Theory of Relativity in Real Life
In the opposite corner, a set of rules called quantum mechanics governs the interactions of the very tiny things in the universe. Quantum mechanics rests on the idea that not much of our everyday experience is smooth and continuous, but chunky. In other words, it's quantized. Energy, momentum, spin and so many other properties of matter come in only discrete little packets.
What's more, quantum mechanics itself also splits itself into two camps. On one hand, we have the familiar particles of our everyday existence, such as electrons and protons, that interact and do other interesting things. These are obviously very chunky, as they're discrete "things." On the other hand, we have the quantum fields. In the subatomic world, each kind of particle has its own field that spreads throughout space-time; when we think of particles, we think of little vibrations in their fields, which in turn interact with other particles, and do some other interesting things. The fields are understandably very smooth.
So, we have some smooth pictures of our universe and some chunky ones. When it comes to space-time itself, we can easily imagine extending the concepts of quantum mechanics all the way to their logical conclusion, and ruling that space and time are discrete: The very fabric of reality is divided up like pixels on a computer screen, and what we experience as smooth, continuous movement is nothing but a grid of discrete pixels at the tiniest of scales.
Related: The Illusion of Time: What's Real?
Many theories of merging together quantum mechanics and general relativity, like string theory and loop quantum gravity, predict some form of discrete space-time (although the precise predictions, interpretations and implications of that chunkiness are still poorly understood). If we could find evidence for discrete space-time, it would not only completely rewrite our understanding of reality, but also open the door to a revolution in physics.
This discreteness can reveal itself only in the most subtle ways; otherwise we would've spotted it by now. Various theories have predicted that if space-time were indeed chunky, then the speed of light may not be entirely constant it may shift ever so slightly depending on the energy of that light. Higher energy light has a shorter wavelength, and when the wavelength becomes small enough, it can "see" the chunkiness of spacetime. Imagine walking down sidewalk: with big feet you don't notice any small cracks or bumps, but if you had microscopic feet you would trip over every little imperfection, slowing you down. But this shift is incredibly tiny; if space-time is discrete, it's on a scale more than a billion times smaller than what we can currently probe in our most powerful experiments.
Enter GrailQuest: the Gamma-ray Astronomy International Laboratory for Quantum Exploration of Space-Time. A team of astronomers submitted a proposal for this mission in response to a call for new space-time-hunting ideas from the European Space Agency (ESA). Their proposal is detailed in the arXiv database, meaning that it hasn't yet been reviewed by peers in the field.
Here's the scoop: In order to see if the speed of light changes with different energies, we need to collect a huge amount of the highest-energy light in the universe, and GrailQuest hopes to do just that.
GrailQuest consists of a fleet of small, simple spacecraft (the exact number varies, from just a few dozen if the satellites are larger to well over a few thousand if they're smaller) to constantly monitor the sky for gamma-ray bursts. These are some of the most powerful explosions in the universe. Like their name suggests, these bursts release copious amounts of high-energy photons, a.k.a. gamma rays. These gamma rays travel across billions of years before reaching the fleet of spacecraft, which record the energy of the gamma rays and the differences in timings as the burst washes over the fleet.
With enough accuracy, GrailQuest might be able to reveal if space-time is discrete. At least, it has the right setup: It's examining the highest-energy light (which is affected the most in theories that predict that space-time is chunky); the gamma rays have been traveling for billions of light-years (allowing the effect to build up over time); and the spacecraft are simple enough to produce en masse (so the entire fleet can see as many events as possible, all across the sky).
How would our conceptions of reality change if GrailQuest were to find evidence for the discreteness of space-time? It's impossible to say our current theories are all over the map when it comes to implications. But no matter what, we're going to have to wait. This round of ESA proposals is for launches sometime between 2035 and 2050. While we're waiting, we can debate if the time elapsed between now and then is fundamentally smooth or chunky.
Paul M. Sutteris an astrophysicist at The Ohio State University, host of Ask a Spaceman and Space Radio, and author of Your Place in the Universe.
Originally published on Live Science.
Visit link:
What If Space-Time Were 'Chunky'? It Would Forever Change the Nature of Reality. - Livescience.com
- A Real Life Hibernation Chamber is Being Made For Deep Space Travel - Futurism - February 7th, 2017 [February 7th, 2017]
- Humans to be FROZEN IN TIME for space travel as scientists move to COLONISE other planets - Express.co.uk - February 7th, 2017 [February 7th, 2017]
- Space flight changes astronauts' brains, research reveals - Fox News - February 7th, 2017 [February 7th, 2017]
- Space travel changes DNA, study finds - STLtoday.com - February 7th, 2017 [February 7th, 2017]
- Space travel visionaries solve the problem of interstellar slowdown ... - Science Daily - February 7th, 2017 [February 7th, 2017]
- Quantum Entanglement May Be Key To Long Distance Space Travel Ex Lockheed Exec Said It's Already Happening - Collective Evolution - February 7th, 2017 [February 7th, 2017]
- Is This Buzz Aldrin-Inspired Locomotive The Future Of Space Travel? - Forbes - February 7th, 2017 [February 7th, 2017]
- Celestial bodies: The Kelly twins offer a vital sign for space travel ... - Pittsburgh Post-Gazette - February 7th, 2017 [February 7th, 2017]
- Space travel visionaries solve the problem of interstellar slowdown at Alpha Centauri - Phys.Org - February 7th, 2017 [February 7th, 2017]
- Newspaper review: Heartthrob and space travel in Wednesday's papers - BBC News - February 8th, 2017 [February 8th, 2017]
- Another View: NASA's Twins Study offers vital sign for space travel - Press Herald - February 8th, 2017 [February 8th, 2017]
- Piece of tragic shuttle history gets a second chance at space travel - WQAD.com - February 9th, 2017 [February 9th, 2017]
- Meet Shawn Pandya, The Third Indian-Origin Woman To Space-Travel - Huffington Post India - February 9th, 2017 [February 9th, 2017]
- Shawna Pandya clears the air on rumours of space travel - Daily News & Analysis - February 10th, 2017 [February 10th, 2017]
- The Expanse and Frankie Adams: Meet the Kiwi who's conquered space travel - Stuff.co.nz - February 10th, 2017 [February 10th, 2017]
- Did a CSU study find that space travel makes you younger? Not so ... - The Denver Post - February 10th, 2017 [February 10th, 2017]
- Twins study offers valuable data on space travel - Herald-Whig - - Herald-Whig - February 10th, 2017 [February 10th, 2017]
- The Expanse and Frankie Adams: Meet the Kiwi who's conquered space travel - Waikato Times - February 11th, 2017 [February 11th, 2017]
- Kelly twins offer a vital sign for space travel - San Angelo Standard Times - February 11th, 2017 [February 11th, 2017]
- Lacoste delves into the world of space travel at New York Fashion Week as Baptista honours founder's lesser-known ... - Evening Standard - February 11th, 2017 [February 11th, 2017]
- NASA's Irish Twins Study reveals first results of space travel on humans - IrishCentral - February 12th, 2017 [February 12th, 2017]
- Starbound to revamp space travel in future update - PC Gamer - February 12th, 2017 [February 12th, 2017]
- How Does Long-Term Space Travel Affect Humans? - Voice of America - February 13th, 2017 [February 13th, 2017]
- A VR Company is Attempting to Make Holographic Videos for Space Travel - Mobile Magazine - February 15th, 2017 [February 15th, 2017]
- Two-Time Space Traveling Astronaut to Speak at Black History ... - Patriots Point - February 16th, 2017 [February 16th, 2017]
- Make space travel great again: NASA, heeding Trump, may add astronauts to a test flight moon mission - National Post - February 16th, 2017 [February 16th, 2017]
- In recently unearthed essay, Winston Churchill anticipated space travel and extraterrestrial life - The Providence Journal - February 16th, 2017 [February 16th, 2017]
- Twins in space: intergalactic travel could change DNA - The Student - February 17th, 2017 [February 17th, 2017]
- An unearthed essay reveals Winston Churchill anticipated space travel and aliens - Stuff.co.nz - February 17th, 2017 [February 17th, 2017]
- Focus Friday: The necessity of space travel - The Daily Cougar - February 17th, 2017 [February 17th, 2017]
- NASA announces $2m investment on technology advancement for deep space travel - WDSU New Orleans - February 17th, 2017 [February 17th, 2017]
- Focus Friday: The necessity of space travel - The Daily Cougar - The Daily Cougar - February 18th, 2017 [February 18th, 2017]
- Ask Ethan: How Can I Travel Through Space Without Getting Into Trouble? - Forbes - February 18th, 2017 [February 18th, 2017]
- Do You Have The Right Personality For Long-Term Space Travel ... - Seeker - February 18th, 2017 [February 18th, 2017]
- In recently unearthed essay, Winston Churchill anticipated space travel and extraterrestrial life - Washington Post - February 18th, 2017 [February 18th, 2017]
- UK bids to be world leader in Space travel by 2020 - Daily Star - February 20th, 2017 [February 20th, 2017]
- Know before you fly: privatized space travel - Observer Online - February 21st, 2017 [February 21st, 2017]
- You could fly to SPACE from the UK within three years as plans are for space port are unveiled - The Sun - February 21st, 2017 [February 21st, 2017]
- Cosmic cinema: spurring interest in real-life space travel? - Miami Student - February 22nd, 2017 [February 22nd, 2017]
- Commercial space travel could be ready as early as 2020 - New York Post - February 22nd, 2017 [February 22nd, 2017]
- This Finnish startup democratizes space travel and it just raised over 3 million to find the next 'Slumdog ... - Business Insider Nordic - February 23rd, 2017 [February 23rd, 2017]
- Commercial space travel WITHIN THREE YEARS on flights to launch from BRITAIN - Express.co.uk - February 23rd, 2017 [February 23rd, 2017]
- Katherine Johnson led African American efforts in space travel - Farm and Dairy - February 23rd, 2017 [February 23rd, 2017]
- Space travel is measured in light years, but what's a light year anyway? - MyStatesman.com - February 23rd, 2017 [February 23rd, 2017]
- TRAPPIST-1: How Long Would It Take to Fly to 7-Planet System? - Space.com - February 24th, 2017 [February 24th, 2017]
- NASA Looking for Bright Ideas to Help With Space Travel - Tech.Co - February 24th, 2017 [February 24th, 2017]
- The history of space travel encapsulated - Fairfaxtimes.com - February 25th, 2017 [February 25th, 2017]
- SpaceX's reusable rockets make space travel much cheaper - The ... - CMU The Tartan Online - February 27th, 2017 [February 27th, 2017]
- Stars align for space travel at memorable Oscars ceremony - Siliconrepublic.com - February 28th, 2017 [February 28th, 2017]
- FSU researcher to lead US-Russia project on health, space travel - Florida State News - February 28th, 2017 [February 28th, 2017]
- Crowding the cosmos: space travel turns private - The Student - March 1st, 2017 [March 1st, 2017]
- Forget SpaceX: 10 companies that will change space travel in 2017 & 2018 - Geektime - March 2nd, 2017 [March 2nd, 2017]
- Safe space travel: Protecting alien worlds from earthlings - and vice versa - Deutsche Welle - March 2nd, 2017 [March 2nd, 2017]
- Watch: 'Black Holes' A Satirical Comedy About Space Travel From Sundance 2017 - Konbini US - March 3rd, 2017 [March 3rd, 2017]
- Doctor Launches Vision Quest To Help Astronauts' Eyeballs - NPR - March 4th, 2017 [March 4th, 2017]
- Beyond Earth talking about space travel - Alaska Public Radio Network - March 4th, 2017 [March 4th, 2017]
- Would You Book A Flight To The Moon? - The Alternative Daily (blog) - March 6th, 2017 [March 6th, 2017]
- Colorado Likely To Benefit From Privatized Space Travel - CBS Local - March 6th, 2017 [March 6th, 2017]
- NEC develops reliable FPGAs for space travel - Electronics Weekly - Electronics Weekly - March 8th, 2017 [March 8th, 2017]
- 4 Entrepreneurs Changing the Way We Think About Space Travel - Tech.Co - March 9th, 2017 [March 9th, 2017]
- Why Space Travel Can Be Absolutely Disgusting - Live Science - March 9th, 2017 [March 9th, 2017]
- EDITORIAL: Exploring private space travel - Indiana Daily Student - March 11th, 2017 [March 11th, 2017]
- Harvard Scientists Theorize That Fast Radio Bursts Come From Alien Space Travel - Popular Mechanics - March 11th, 2017 [March 11th, 2017]
- Space Exploration: US congress approves $19.5 billion for NASA to get humans to Mars by 2033 - NTA News - March 11th, 2017 [March 11th, 2017]
- MIT Conference To Focus On Space Travel For The Public - CBS Boston / WBZ - March 11th, 2017 [March 11th, 2017]
- Reusing rockets is best way to advance space travel, SpaceX officer tells symposium attendees - Colorado Springs Gazette - April 8th, 2017 [April 8th, 2017]
- How space travel leads to cognitive shifts in awareness | Life and ... - The Guardian - April 8th, 2017 [April 8th, 2017]
- Cheap space travel, electric cars and a whirlwind love life love life... the billionaire genius inventing our future - Mirror.co.uk - April 8th, 2017 [April 8th, 2017]
- Reusable rockets key for space travel industry - Alamogordo Daily News - April 8th, 2017 [April 8th, 2017]
- Is this massive airplane the future of space travel? One billionaire thinks so. - SOFREP (press release) (subscription) - June 6th, 2017 [June 6th, 2017]
- spotlight - NYCAviation - June 6th, 2017 [June 6th, 2017]
- BBC commissions documentary about commercial space travel fronted by Brian Cox - Radio Times - June 6th, 2017 [June 6th, 2017]
- The Physics of Interstellar Travel : Explorations in ... - June 6th, 2017 [June 6th, 2017]
- Mars rover scientist, SpaceX engineer join NASA astronaut corps - Reuters - June 7th, 2017 [June 7th, 2017]
- How SpaceX Launched a Chinese Experiment Into Space, Despite US Ban - Foreign Policy (blog) - June 7th, 2017 [June 7th, 2017]
- 'Blast Camp' gives students lessons on space travel - Fremont News Messenger - June 7th, 2017 [June 7th, 2017]
- IKEA looks to space travel for new micro-living furniture collection - Dezeen - June 7th, 2017 [June 7th, 2017]
- HPE's next frontier: Space travel & memory-driven computing - IT Brief Australia - June 8th, 2017 [June 8th, 2017]
- 20 Out-Of-This-World Companies Working On Space Travel Technologies - Interesting Engineering - June 12th, 2017 [June 12th, 2017]
- Here's how space travel is helping keep you healthy - Eyewitness News - June 12th, 2017 [June 12th, 2017]