European Satellite to Test Method to Find Ripples in Space, Time

[Kashmiri Pandit]

CAPE CANAVERAL, FLORIDA—
An experimental satellite slated for launch on Wednesday will test a technique to detect ripples in space and across time, adding a new perspective for viewing and understanding the universe.

From a vantage point 93 million miles (1.5 million kilometers) from Earth, the European-built spacecraft, known as LISA Pathfinder, is expected to break ground in the search for the ripples, known as gravitational waves, caused by fast-moving, massive celestial objects such as merging black holes.

Black holes are so dense with matter that not even photons of light can escape the powerful gravitational effects.

"This will really open up a new window into the universe. God knows what we will learn," said European Space Agency deputy mission scientist Oliver Jennrich.

Like light, gravity travels in waves. Unlike light, gravitational waves bend the interwoven fabric of space and time, a phenomenon conceptualized by physicist Albert Einstein a century ago. Before Einstein's general theory of relativity, gravity was seen as a force between two bodies.

In the pre-Einstein view of physics, if the sun disappeared one day, people on Earth would feel it instantly. In Einstein's view, the effects would not be felt for eight minutes, the time both light waves and gravitational waves take to travel from the sun to Earth.

'Spectrum of gravitational waves'

So far, attempts to detect gravitational waves using Earth-based detectors have been unsuccessful.

Massive objects such as black holes bend space and time more than smaller bodies like the sun, similar to how a bowling ball warps the surface of a trampoline more than a baseball.

"There's a whole spectrum of gravitational waves, just like there's a whole spectrum of electromagnetic waves," said astrophysicist Ira Thorpe of NASA's Goddard Space Flight Center.

An operational gravitational wave observatory under development would require three satellites, flying in a triangle formation about 621,000 miles (1 million kilometers) apart. The satellites would contain small metal cubes that would oscillate as a gravitational wave passes through, similar to a buoy rising and falling on the ocean.

Using a laser to measure tiny changes in distance between the cubes, scientists hope to track the subtle flexing of space and time. LISA (Evolved Laser Interferometer Space Antenna) Pathfinder will demonstrate the concept with two metal cubes 15 inches (38 cm) apart inside a single spacecraft.

Launch is set for 0415 GMT on Wednesday (11:15 p.m. EST on Tuesday) from the European Space Agency's Kourou, French Guiana launch site. It will need six weeks to reach its intended orbit and another three months to prepare for science operations.

 

[Kashmiri Pandit]

@Providence @Nilgiri @Spectre @Chinese-Dragon @Godman

 

[Providence]

I am not sure how they are gonna measure this gravitational wave fluctuation.. I mean gravitational wave is a 4D thing right ? Aren't we supposed to be 5th dimension to measure fluctuations in it ?

 

[Kashmiri Pandit]

I am not sure how they are gonna measure this gravitational wave fluctuation.. I mean gravitational wave is a 4D thing right ? Aren't we supposed to be 5th dimension to measure fluctuations in it ?

Ur words are going over my Head

 

[Providence]

Ur words are going over my Head

Brother don't worry. I am just spitballing here .. some learned member can throw some light !

 

[Nilgiri]

I will shed some light on this a little later.

 

[Nilgiri]

I am not sure how they are gonna measure this gravitational wave fluctuation.. I mean gravitational wave is a 4D thing right ? Aren't we supposed to be 5th dimension to measure fluctuations in it ?

If by 4D you mean spacetime....yes.

You do not need higher dimensions to measure something in a lower dimension....rather you need to be in the higher dimension to use it/control it.

Thats why we can measure time and space for instance....but we cannot control them.

The problem with measuring gravity waves specifically is sorting out the noise. Take a regular radio antenna, it picks up every source of radiation out there...but it's geometry is optimized specifically for a range of frequencies (radio frequencies)...and we pump out large amplitude signals at various intervals of them to distinguish clearly from the "static noise" that everyone has heard (I hope).

Gravity waves are essentially a tiny tiny part of this static, with tons and tons of other noise around them ( a large part from our own Sun and the big bang "noise")

Laser interferometry is basically senstive enough to measure them (hopefully).....by basically targetting a range of frequencies we know to be relatively silent (very very low frequency). The problem is that this requires phenomenally large antenna (interferometry is just a laser based antenna essentially in this case).....and another problem is on Earth we have the atmosphere and a lot of distortion and noises bouncing off it etc.. Thats why all the ground based ones have been unsuccesful so far (but efforts are ongoing given its a lot cheaper to hedge here while we wait for space-based ones)

So the vacuum of space is much more ideal, and we would essentially need to set up a space based constellation to act as the overall antenna. But such missions take much research effort, resources and time (this one is 2034 launch date). I would imagine certifying just a simple thing as a collimator for this power level of these sorts of lasers would be a phenomenal task by itself (judging by the distances being talked about).

Hope this explanation clears up the basics!